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The development of nanotechnologies and nanomaterials begins in 1931, when the German physicists Max Knoll and Ernst Ruska created an electron microscope, which for the first time made it possible to study nanoobjects. Later in 1959, American physicist Richard Feynman (Nobel laureate in physics, 1965) first published a paper evaluating the prospects for miniaturization called Down There, a Sea of ​​Place. He stated: “So far we are forced to use the atomic structures that nature offers us ... But, in principle, a physicist could synthesize any substance according to a given chemical formula.” Then his words seemed like science fiction, because there were no technologies that would allow operating with individual atoms at the same atomic level (meaning the ability to know a separate one, take it and put it in its place). Feynman even offered a $1,000 reward to whoever could practically prove him right.

History of development of nanotechnology

In 1974, the Japanese physicist Norio Taniguchi coined the term "nanotechnology" to describe mechanisms smaller than one micron in size.

German physicists Gerd Binnig and Heinrich Rohrer created a scanning tunneling microscope (STM), which made it possible to manipulate matter at the atomic level (1981), later they received the Nobel Prize for this development. The scanning atomic force (AFM) microscope further expanded the types of materials studied (1986).

In 1985, Robert Curl, Harold Kroto, Richard Smalley discovered a new class of compounds - fullerenes (Nobel Prize, 1996).

In 1988, independently of each other, French and German scientists Albert Fert and Peter Grünberg discovered the effect of giant magnetoresistance (GMR) (in 2007, the Nobel Prize in Physics was awarded), after which magnetic nanofilms and nanowires began to be used to create magnetic recording devices. The discovery of HMS became the basis for the development of spintronics. Since 1997, IBM has begun to manufacture spintronic devices on an industrial scale - heads for reading magnetic based on GMR with dimensions of 10-100 nm.

HMS, or, otherwise, giant magnetoresistance(eng. giant magnetoresistance abbr., GMR) - is the effect of a change in the electrical resistance of a sample under the influence of a magnetic field (mainly in heterostructures and superlattices), which differs from the magnetoresistance in the scale of the effect (it is possible to change the resistance by tens of percent, in contrast to the magnetoresistance, when the change resistance does not exceed a few percent). His discovery made possible the development of modern storage media for computers - hard disk drives (HDD)

1991 was marked by the discovery of carbon nanotubes by the Japanese researcher Sumio Iijima.

In 1998, a transistor based on nanotubes was first created by Cees Dekker (Dutch physicist). And in 2004, he combined a carbon nanotube with DNA, for the first time obtaining a full-fledged nanomechanism, thereby opening the way to the development of bionanotechnology.

2004 - the discovery of graphene, for the study of its properties, A. K. Geim and K. S. Novoselov were awarded the Nobel Prize in Physics in 2010. Well-known firms IBM, Samsung finance scientific projects to develop new electronic devices that could replace silicon technology.

General characteristics of nanotechnologies and nanomaterials

Nanotechnology (NT)(the Greek word "nannos" means "dwarf") is a set of methods for manipulating matter at the atomic or molecular level in order to obtain predetermined properties.

1 nanometer(nm) = 10 -9 meters.

Nanotechnology refers to technologies that provide the ability to create and modify nanomaterials in a controlled manner, as well as to integrate them into fully functioning systems on a larger scale. Nanotechnology uses: atomic communication of molecules, local stimulation of chemical reactions at the molecular level, etc. Nanotechnology processes are subject to the laws of quantum mechanics.

Today, the main branches of nanotechnology are: nanomaterials, nanotools, nanoelectronics, microelectromechanical systems and nanobiotechnologies.

Task NT:

• obtaining nanomaterials with a given structure and properties;
• application of nanomaterials for a specific purpose, taking into account their structure and properties;
• control (research) of the structure and properties of nanomaterials both during their production and during their use.

There are two main approaches to nanomanufacturing: above down and upwards. The top-down technology is to grind a material that has large dimensions (massive material) to nano-sized particles. In a bottom-up approach, nanomanufacturing products are created by growing (creating) them from the atomic and molecular scales.

Manufacture at the nanoscale is known as nanomanufacturing - it involves large-scale activities, the creation of a reliable and cost-effective production of nanoscale materials, structures, devices and systems. It provides for research, development and integration of technologies from the top down and more complex - from the bottom up or self-organization processes.

Nanomaterials are dispersed or massive materials (structural - grains, crystallites, blocks, clusters), the geometric dimensions of which do not exceed 100 nm in at least one dimension and have qualitatively new properties, functional and operational characteristics, which are manifested due to nanoscale dimensions.

All substances in the initial state or after a certain processing (grinding) have a different degree of dispersion, the size of the constituent particles can not be seen with the naked eye.

Objects with sizes in the range of 1-100 nm are considered to be nanoobjects, but such restrictions are very conditional. In this case, these dimensions can concern both the entire sample (the entire sample is a nanoobject) and its structural elements (its structure is a nanoobject). The geometric dimensions of some substances are given in the table.

The main advantages of nanoobjects and nanomaterials is that, for their small size, new special properties appear in them, which are not characteristic of these substances in a massive state.

Classification of a substance depending on the degreedispersion

state of matter	fragmentation of matter	Degree of dispersion, cm -1	Number of atoms in a particle, pcs.
macroscopic	coarse	10 0 -10 2	> 10 18
Means of observation: naked eye
microscopic	finely dispersed	10 2 -10 5	> 10 9
Observation tool: optical microscope
colloidal	ultrafine	10 5 -10 7	10 9 -10 2
Observation means: optical ultramicroscope, electron and scanning probe microscope
Molecular, atomic and ionic	Molecular, atomic and ionic	> 10 7	<10 2
Observation medium: high resolution microscope (<0,1 нм) и сканирующий микроскоп

The properties of nanomaterials are determined by their structure, which is characterized by an abundance of interfaces (grain boundaries and triple junctions—lines of contact between three grains). The study of the structure is one of the most important tasks of nanostructural materials science. The main element of the structure is grain or crystallite.

Size classification. According to the dimensional feature, nano-objects are divided into three types: zero-dimensional / quasi-zero-dimensional (0D), one-dimensional (1D), two-dimensional (2D).

Nano-objects zero-dimensional / quasi-zero-dimensional (0D) are nanoparticles (clusters, colloids, nanocrystals and fullerenes) containing from several tens to several thousand atoms grouped into bonds or ensembles in the form of a cell. In this case, the particle has nanometer dimensions in all three directions.

Nanoparticles are nanoobjects in which all characteristic linear dimensions are of the same order of magnitude (up to 100 nm). As a rule, nanoparticles have a spherical shape and, if they have a pronounced ordered arrangement of atoms (or ions), then they are called nanocrystallites. Nanoparticles with pronounced discreteness of energy levels are often called "quantum dots" or "artificial atoms".

Comparison of the geometric dimensions of materials

Nanoobjects are one-dimensional(1D)- carbon nanotubes and nanofibers, nanorods, nanowires, that is, cylindrical objects with one dimension of several microns and two nanometers. In this case, one characteristic size of the object is at least an order of magnitude greater than the other two.

Nanoobjects are two-dimensional(2D) - coating or films several nanometers thick on the surface of a bulk material (substrate). In this case, only one dimension - the thickness should be nanometer dimensions, the other two are macroscopic.

Special properties of nanomaterials

At the macroscale, the chemical and physical properties of materials are independent of size, but as you move to the nanoscale, everything changes, including the material's color, melting point, and chemical properties. Mechanical properties change significantly in nanocrystalline materials. Under certain conditions, these materials can be superhard or superplastic. The hardness of nanocrystalline nickel in the transition to nanoscale increases by several times, and the tensile strength increases by 5 times. melting of clusters (more than 1000 atoms) of gold becomes the same as for bulk gold. Adding nanostructured aluminum to rocket fuel radically changes its rate of combustion. The thermal conductivity of motor oil increases significantly with the addition of multilayer carbon nanotubes.

Thus, in nanocrystalline and nanoporous materials, the specific surface sharply increases, that is, the fraction of atoms in a thin (~ 1 nm) near-surface layer. This leads to an increase in the reactivity of nanocrystals, since the atoms located on the surface have unsaturated bonds, in contrast to those located in the bulk and associated with neighboring atoms.

Experimental data obtained in different laboratories for nanopowders indicate that, in most cases, the sensitivity to ignition from an electric spark, collision, or mechanical friction and the intensity of combustion increase with a decrease in the particle size in a dust cloud (and, accordingly, with an increase in specific surface area).

If the metal particles have dimensions of the order of microns - nm, then their minimum ignition (MEI) is significantly reduced and is less than 1 mJ (this is the lower sensitivity limit of the apparatus that is usually used to measure the MEZ). The dependence of the particle sizes of Al, polyethylene, and optical brightener on the IEZ was studied. The results for the flammability of Al are shown in the table. According to the data obtained, the maximum explosion pressure P max increases upon transition to the nanorange, the minimum ignition concentration (MCC) does not change significantly, and the IES sharply decreases by at least 60 times.

Flammability of Al particles

Particle size	P max , bar	MKZ, g / 3	MEZ, mJ
40 µm 100 nm 35 nm

The size dependence of the surface energy of nanocrystals leads to the corresponding dependence of the melting temperature, which becomes lower for nanocrystals than for macrocrystals. In general, a noticeable change in thermal properties is observed in nanocrystals, which is associated with a change in the nature of thermal vibrations of atoms. In ferromagnetic nanoparticles, as the size decreases below a certain critical value, the state of division into domains becomes energetically unfavorable for the system. As a result, nanoparticles are transformed from polydomain to single-domain, while obtaining special magnetic properties.

Fields of science related to nanotechnology

Interdisciplinarity is a characteristic of a branch of knowledge or a scientific problem, where a successful result can only be achieved by combining the efforts of individual sciences. The integration of knowledge of individual scientific branches leads to synergy - the acquisition of qualitatively new knowledge, which, due to its unique properties, has been applied in many areas of knowledge.

Spintronics- the direction of the branch of modern electronics, based on the use of spin effects and quantum properties of the spin of electrons, characterized by two quantum states (spin up and spin down). The change in the orientation of the spins occurs due to the action of a high current density passing through ultrathin ferromagnetic structures (sandwiches). The orientation of the spins remains unchanged if the polarized current source is turned off, so spintronic devices are very widely used as readheads, memory devices on the GMO phenomenon and tunnel MO, current controlled alternating voltage generators, field effect transistors, and the like.

Nanobiology- a branch of biology devoted to the study of structural, biological, biophysical processes in natural biological structures or their nanobiological counterparts, the laws that biological systems are subject to. The creation of operating nanomodels of biological structures on this basis today form the basis of nanobiology. Achievements in the science of nanobiology form the basis for the development of such areas of nanoscience as bioorganic nanochemistry, nanopharmaceutics, nanosensors, nanomedicine, and the like.

Molecular electronics explores electronic nanosystems containing, as constituents, single molecules or molecular complexes, as well as manufacturing technologies for such nanosystems based on the use of self-assembly processes, including the manipulation of both single molecules and molecular complexes.

Nanosensorics — a branch of science about sensory nanosystems, the operation of which is based on the selective perception of signals of various nature: biological, chemical, temperature, etc., and their conversion into electrical ones (bionanosensors that can not only track the state of the body, but also automatically perform some necessary actions ).

Nanooptics— a field of science devoted to optical nanosystems that perform the functions of information management, processing, storing and transmitting information in the form of optical signals. A promising section of nanooptics is nanophotonics, its elemental base is made up of photonic crystals, which are effectively used in devices for processing, storing and transmitting information.

nanomechanics(nanorobotics) is a field of technology involved in the creation of nanorobots capable of performing certain medical operations in the patient's body (nanocatheters that allow efficient diagnosis and therapy in blood vessels and the intestinal tract, as well as dosing and distributing nanodevices that ensure the delivery of drugs needed by patients ). In addition, the small size of microcomponents makes them ideal for manipulating biological samples at the microscopic level.

Applications of nanotechnology

NT are becoming increasingly important and can be used in all industrial sectors, in particular in electronics, solar industry, energy, construction, automotive, aircraft manufacturing, medicine, etc.

Electronics. The development of the technological process in the manufacture of transistors in computer technology (microprocessors) is gradually decreasing from 90 to 14 nm, which is not the limit (it is planned to reduce it to 10-8 nm by 2019). Thus, a billion transistors will be placed on one centimeter of silicon.

Thanks to the development of materials science and microelectronics, the unit cell of memory devices is decreasing. At present, materials based on superlattices, diamagnets, ferromagnets, in which the effect of giant magnetic resistance, perpendicular composition and anisotropy is realized, are becoming promising.

Among semiconductor technologies, we note lasers operating at low temperatures, have a low generation threshold (up to 15 μA), which will be widely used, for example, in quantum cryptography.

The combination of the latest results obtained from the field of materials science and electronics allows you to create devices with unique flexible, moisture and impact resistant properties, have a high efficiency and long service life. The use of new materials makes it possible to create highly efficient photodetector equipment for visible and infrared radiation, the use of which will increase the efficiency of monitoring power lines, pipelines, and security systems.

Energy. Energy supply issues are always relevant, they provide for two main tasks - the creation of devices with economical power consumption and the manufacture of chargers based on new technologies with improved performance. Lighting equipment is being modernized, incandescent lamps are being replaced with bright LEDs and matrices based on them.

Considerable attention is paid to alternative forms of energy. Thus, solar cells have been developed that absorb energy in the infrared part of the spectrum. This is due to a technology that uses a special manufacturing process to deposit metal nanoantennas (tiny square coils) on a plastic substrate. This design allows you to get up to 80% of the energy of sunlight, while existing solar panels can only use 20%. radiates a lot of thermal energy, some of which is absorbed by the earth and other objects and radiated for many hours after sunset; nanoantennas "capture" this thermal radiation with higher efficiency than conventional solar panels.

The creation of batteries based on silicon nanofibers containing lithium ions instead of carbon will lead to an increase in the capacity of chargers and an expansion of the range of use. The ionic conductivity of solid electrolyte nanocomposites increases by several orders of magnitude, due to which miniature flexible batteries can be fabricated on its basis.

The medicine. Nanostructuring leads to a decrease in the size of the tablet and an increase in the content of the therapeutic substance in the blood. This is very important, because in the future nanoparticles will be one of the means of drug delivery to the affected area (nanorobots). Silver nanoparticles due to their bactericidal properties are used in the treatment of various wounds for the purpose of disinfection. The typical size of silver nanoparticles is 5-50 nm, they are added to detergents, toothpastes, wet wipes, applied to the surfaces of air conditioners, cutlery, door handles (in places where there is a high risk of spreading infections) and even keyboards and mice for computers. Gold nanoparticles together with antibodies can reduce the harmful effects of radiation in the treatment of tumors.

Modern equipment allows you to "see the life" of living cells, perform manipulations with molecules and makes it possible to grow or clone parts of organs. The combination of biological and medical knowledge, together with advances in electronics, makes it possible, using nanotechnologies and nanomaterials, to create microelectronic devices (chips) for monitoring human or animal health.

UDC 621.3.049.77

Zh.I.Alferov, acad. RAS, P.S. Kopiev, Dr. phys.-math. sciences, prof., R.A.Suris, member corr. RAS, A.F. Ioffe Physical-Technical Institute RAS (St. Petersburg);

A.L. Aseev, corresponding member RAS, Institute of Semiconductor Physics SB RAS (Novosibirsk);

S.V. Gaponov, corresponding member RAS, Institute of Physics of Microstructures RAS (Nizhny Novgorod);

V.I. Panov, Dr. phys.-math. Sciences, prof., Moscow State University. M.V. Lomonosov (Moscow),

E.A. Poltoratsky, Dr. phys.-math. Sci., prof., State Research Institute for Physical Problems. F.V. Lukina (Moscow),

N.N.Sibeldin, Dr. phys.-math. Sciences, Physical Institute. P.N.Lebedev RAS (Moscow)

NANOMATERIALS AND NANOTECHNOLOGIES

A brief review of the current state of the art is given and some prospects in the field of nanomaterials and nanotechnologies are described. The basic concepts of semiconductor, magnetic and molecular nanostructures, x-ray multilayer mirrors, fullerene-like and structural nanomaterials are presented. The application of nanostructures in electronics and the prospects opened up in connection with this in information technologies, communication engineering, etc. are considered. The fundamentals of nano- and microelectromechanics are described: technologies, element base, devices and systems. Methods for diagnosing nanostructures are considered.

Introduction

The physics of low-dimensional structures is the most relevant and most dynamically developing area of ​​modern solid state physics. Interest in this area is associated both with fundamentally new fundamental scientific problems and physical phenomena, and with the prospects of creating, on the basis of already discovered phenomena, completely new quantum devices and systems with broad functionality for opto- and nanoelectronics, measuring equipment, new generation information technologies, means of communication, etc. The result of the study of low-dimensional systems was the discovery of fundamentally new, and now widely known phenomena, such as the integer and fractional quantum Hall effect in a two-dimensional electron gas, the Wigner crystallization of quasi-two-dimensional electrons and holes, the discovery of new composite quasiparticles and electronic excitations with fractional charges, high-frequency Bloch oscillations, and much more. Modern semiconductor lasers based on heterojunctions are also based on the use of low-dimensional systems (structures with quantum wells, self-organized quantum dots, and quantum wires). The most outstanding achievements in this area have been awarded three Nobel Prizes in Physics (1985 - for the discovery of the quantum Hall effect; 1998 - for the discovery of the fractional quantum Hall effect; 2000 - for the work that laid the foundations of modern information technology).

The development of this field has opened up the possibility of designing by means of band engineering and engineering of wave functions and subsequent fabrication using modern high technologies of nanostructures (superlattices, quantum wells, dots and threads, quantum contacts, atomic clusters, etc.) with an electronic spectrum and properties required for discovering and studying new physical phenomena or for related applications. Nanostructures constructed in this way are, in essence, artificially created materials with predetermined properties.

Undoubtedly, the element base based on the use of various low-dimensional structures is the most promising for new generations of electronic equipment. However, when moving to systems of the nanometer scale, the quantum mechanical nature of quasiparticles in a solid begins to be clearly manifested. As a result, a fundamentally new situation arises when quantum effects (dimensional quantization, confinement, tunneling, interference of electronic states, etc.) will play a key role in physical processes in such objects and in the operation of devices based on them.

Achievements in the design and manufacture of nanostructures for various purposes are largely determined by the level of development of technologies that make it possible to obtain nanostructures of the required configuration and dimension with atomic precision, as well as methods for complex diagnostics of the properties of nanostructures, including control during the manufacturing process (in situ) and control based on it. technological processes. According to many forecasts, it is the development of nanotechnology that will determine the shape of the 21st century, just as the discovery of atomic energy, the invention of the laser and the transistor determined the shape of the 20th century.

Below is a brief overview of the current state and some of the prospects in the field of nanomaterials and nanotechnologies, which, we hope, will provide an overview of this area. At present, this is a very extensive area, which includes a number of areas of physics, chemistry, biology, electronics, medicine and other sciences. Therefore, a more detailed presentation would require a significant increase in the volume of this article.

Nanomaterials

If, when the volume of a substance is reduced along one, two, or three coordinates to the size of a nanometer scale, a new quality arises, or this quality arises in a composition of such objects, then these formations should be attributed to nanomaterials, and the technologies for their production and further work with them - to nanotechnologies. The vast majority of new physical phenomena on the nanoscale stems from the wave nature of particles (electrons, etc.), whose behavior obeys the laws of quantum mechanics. The easiest way to explain this is on the example of semiconductors. When in one or more coordinates the dimensions become of the order of and less than the de Broglie wavelength of charge carriers, the semiconductor structure becomes a resonator, and the spectrum of charge carriers becomes discrete. The same with X-ray mirrors. The thicknesses of the layers capable of reflecting X-rays in phase lie in the nanometer range. In other cases, the emergence of a new quality may be associated with less obvious phenomena. It seems that such an approach makes it possible to form a fairly complete picture of nanomaterials and possible areas of their application.

Semiconductor nanostructures

Using the methods of "band engineering" and "wave function engineering" it is possible to design quantum-dimensional structures with a given electronic spectrum and the required optical, electrical and other properties. Therefore, they are very suitable for instrumental applications.

quantum wells. This term refers to systems in which there is a dimensional quantization of the movement of charge carriers in one direction. Initially, the main studies of quantum wells were carried out on the inversion channels of silicon MOS transistors, later and to the present time, the properties of quantum wells in heterostructures have been widely studied. The main physical phenomena in quantum wells are: size quantization of the electronic spectrum, quantum Hall effect (integer and fractional), with special preparation very high electron mobility. The main methods for obtaining quantum wells on heterostructures: organometallic gas epitaxy and molecular beam epitaxy.

Instrument applications: high-frequency high electron mobility field-effect transistors, near-IR to blue light semiconductor heterolasers and LEDs, far-IR lasers, mid-IR parametric light sources, mid-IR photodetectors, far-IR dopant photodetectors, far-IR receivers at quantum Hall effect, modulators in the near-IR range.

quantum wires These are systems in which the motion of charge carriers is quantized in two directions. The first quantum wires were made on the basis of quantum wells by creating a potential relief using two gates located above the quantum well. Basic physical phenomena in quantum wires: quantization of conductivity, strongly correlated electron transport. The basic methods for obtaining quantum wires are the same as for quantum wells, plus the use of precision etching or special gates. There are no instrumental applications yet.

quantum dots- nanoobjects in which the movement of charge carriers is quantized in all three directions. They have a discrete energy spectrum (artificial atom). Basic physical phenomena in quantum dots: one-electron and one-photon phenomena. The production methods are the same as for quantum wells, but somewhat different modes, if there is a spontaneous growth of quantum dots according to the Stransky-Krastanov mechanism. Or using precision lithography to create quantum dots from quantum wells.

Device applications: lasers and LEDs in the near-IR range, photodetectors for the mid-IR range, single-photon receivers, single-photon generators, single-electron transistors.

Structures with tunnel-transparent barriers(systems of quantum wells and superlattices). The main physical phenomena in such systems are: resonant tunneling; formation of a miniband spectrum in superlattices - periodic systems containing many quantum wells separated by tunnel-transparent barriers; nonlinear electrical and optical phenomena in superlattices. The methods for growing these structures are the same as for quantum wells.

Instrument applications: resonant tunneling diodes (generators and mixers in the gigahertz and terahertz ranges); high-power generators and mixers based on superlattices: cascade lasers in the mid- and far-IR ranges.

Photonic Crystals- systems in which there is a zone spectrum for photons. Basic physical phenomena: lack of transmission (total reflection) of light in a certain frequency range, resonant photon states. There are several methods for making photonic crystals, but all of them are still imperfect.

Possible instrumental applications: efficient lasers with low threshold currents, light flux control systems.

Magnetic nanostructures

The development of methods for deposition of ultrathin films and nanolithography has led in the last decade to an active study of magnetic nanostructures. The impetus for this activity is the idea of ​​creating new magnetic nanomaterials for ultra-dense recording and storage of information. It is assumed that each particle carries one bit of information. If the distance between particles is 100 nm, then the expected recording density is 10 Gbit/cm2. The fundamental limitations of the recording density in this approach are the magnetostatic interaction of particles and significant thermal fluctuations. The latter have a significant specificity for small ferromagnetic particles, which manifests itself in an exponential increase in the probability of decay of the magnetized state with decreasing particle size (superparamagnetism).

The discovery of the effect of giant magnetoresistance should be recognized as an achievement in the study of the magnetism of nanomaterials. The essence of the effect is to change the resistance (of the order of several tens of percent) of a multilayer structure of ultrathin ferromagnetic and diamagnetic layers (for example, So/Cu) when the ferromagnetic ordering in the structure changes to antiferromagnetic. It can be said that such multilayer structures represent a new type of domain structure of a ferromagnet, in which the role of domains is played by ferromagnetic films, and the domain walls are films of a diamagnet. This effect finds its application in the creation of new magnetic field sensors, as well as in the development of media for ultra-dense recording of information.

Further progress into the region of small sizes led to the discovery of a new phenomenon - tunneling of the magnetic moment in ultra-small ferromagnetic particles. This group of nanomaterials includes artificial crystals containing magnetic clusters Mn 12 and Fe 3 . The magnetic moment of such clusters is equal to 10 Bohr magnetons, i.e. occupies an intermediate position between the magnetic moment of atoms and macroscopic particles. There is no exchange interaction between clusters in the crystal, and the magnetic anisotropy is very high. Thus, the possibility of quantum transitions between magnetic equilibrium states in clusters appears. The study of these processes is interesting and important from the point of view of developing the element base of quantum computers.

Two-Dimensional Multilayer Structures of Nano-Thick Films

In this case, such combinations of materials are considered that provide the strongest reflection of electromagnetic waves. The wavelength of the radiation effectively interacting with the multilayer structure and its period are related by the relation , where is the glancing angle of the incident beam. The wavelength range in which the use of these devices is effective extends from extreme ultraviolet radiation (nm) to hard X-ray (nm), i.e. the range in which the longest waves are 6000 times larger than the shortest. For visible light, this ratio is ~2. Accordingly, the number of natural phenomena, the physical manifestations of which are located in this spectral region, is just as large.

The structures are artificial one-dimensional crystals of nanometer-thick films, and besides the possibility of using them to control radiation depending on the layer materials (insulator, semiconductor, metal, superconductor), they may also be of interest for other physical applications. So, if one of the materials of multilayer nanostructures is a superconductor, then this is a system of multiple series-connected completely identical Josephson junctions. If the metal alternates with a semiconductor, this is a system of series-connected Schottky diodes.

In the shortest part of the range 0.01-0.02 nm, X-ray mirrors make it possible to focus the radiation of synchrotrons or X-ray tubes on the objects under study or to form parallel beams. In particular, their use increases the efficiency of X-ray tubes by 30-100 times, which makes it possible to replace synchrotron radiation in a number of biological, structural and material science studies. Approximately in the same range lies the radiation of high-temperature plasma (laser and TOKAMAKS). Here, mirrors have found application as dispersive elements for spectral studies.

In the range of 0.6-6 nm lies the characteristic radiation of light elements from boron to phosphorus. Here, X-ray mirrors are also used to study the spectra in devices for elemental analysis of materials.

X-ray multilayer optics is widely used for filtering and polarization control in synchrotron sources. In the region of 10-60nm there are radiation lines of the solar plasma. The objectives of space telescopes made of X-ray mirrors are still in orbit and regularly transmit to Earth an image of the Sun on the Fe IX-Fe XI (17.5 nm) and He II (30.4 nm) lines.

A special place is occupied by the use of multilayer mirrors in microelectronics technologies. We are witnessing and participating in the biggest event in solid state electronics: the transition to a wavelength more than 10 times shorter (from 157 nm to 13 nm) in lithography, a process that provides the drawing of semiconductor devices and integrated circuits. It is the wavelength of the radiation used to obtain the pattern that is responsible for the size of its minimum elements. Until now, the change in the radiation wavelength from generation to generation of lithographic installations did not exceed 25%. At the same time, the requirements for manufacturing accuracy of all optical elements and adjustment and exposure mechanisms are increased by 10 times. In fact, this means the transition of all processing technologies to atomic precision. Non-participation in this process can leave the country in the past civilization.

Molecular nanostructures

Recently, organic materials have been intensively involved in nanotechnologies both as integral participants in the technological process (for example, in nanolithography) and as independent objects and devices - in the so-called molecular electronics.

The diversity of the organic world is well known (about 2 million synthesized compounds, and this number is constantly growing) - from "semi-inorganic" complexes (carbon clusters, organometallics) to biological objects (DNA, hemes). From the point of view of materials for nanotechnology and molecular electronics, three main classes can be conventionally distinguished: polymers, molecular assemblies (molecular assemblies, selfaggregated systems), and single molecules: the latter are also called "smart" or "functional" molecules (smart molecules).

First grade has been studied for the longest time and, according to the total set of works, probably the most intensively. In addition, the dielectric, optical and luminescent properties of various poly- and oligomers are already widely used in engineering and electronics, they are closest to the market and economic effect.

Second class- molecular ensembles of nano-meter sizes - has been studied relatively recently. These include, for example, aggregates based on porphyrins (including chlorophyll) and other amphiphilic molecules obtained from solutions. Supramolecular (that is, supramolecular, hierarchical) organization is complex and interesting, its study and connection with (photo-) electrical properties sheds light on biological and natural processes (cellular transport, photosynthesis). The sensitivity, and most importantly, the unique selectivity of such systems to external influences (light, atmosphere, vibration), was found, which makes it possible to use them in various sensors, including those with mixed electron-ion conductivity. Nanosized molecular rods and wires are being studied, including as an interface between inorganic materials (for example, two metal electrodes). It is assumed that over time there will be integration with the classical instrumental base.

In general, systems built mainly on van der Waals or hydrogen bonds are a very promising object from the point of view of solid state design with two levels of freedom: an intramolecular structure that can be modified (changed during synthesis) and which is responsible, for example, for the absorption or emission of light; intermolecular structure, which can be changed during the growth of a crystal (film, epitaxial layer), and which is responsible for phase phenomena, charge carrier transport, and magnetic properties. As an example, copper phthalocyanine and peripherally fluorinated copper phthalocyanine are structurally isomorphic, but are - and -type semiconductors, respectively. Fully organic rectifying junctions based on vacuum-deposited layers are being intensively studied at present. At the same time, doping of phthalocyanine films with a strong acceptor (for example, iodine) changes the phase structure up to obtaining a quasi-one-dimensional metallic conductivity.

An important group also includes self-assembled monolayers (SAM "s) based on organic molecules or chains of various structures, which are used to study both promising transmitting materials in lithography and to study electrotransport along the molecular conjugation contour. The third class already begins here.

The third class or method of using organic materials in nanotechnology is the youngest. This is what Western competitions call emergent or futuristic technologies (suddenly emerging or futuristic technologies). If liquid crystal displays, CD-R technologies, photoconverters, sensors and other devices based on organic materials are well known and gradually (albeit slowly due to understandable inhibition from the already widely invested and promoted "silicone" and GaAs priority) come to the market, there are no single-molecular devices (devices) in real production. Moreover, if the macroscopic properties of classical organic solids (molecular crystals) have a satisfactory theoretical description, then the processes expected in single-molecular devices are seen much less clearly. The most simplified approach: we take a certain molecule, which is a well-organized quantum system, we make electrodes for it and we get, for example, a diode. This immediately raises many new questions. In particular, the metal/molecular semiconductor interface, even at the macro level, is rather uncertain.

Nevertheless, truly "nanoscale" effects are expected in this class. Molecular nanomachines and nanomotors (rotors), dynamic molecular switches, energy transporters, recognition and information storage devices are being designed. To study the injection of carriers and tunneling current in individual molecules, methods of probe microscopy are being improved.

However, one should not forget that among the main advantages (if not the most important) of organics are cheapness and availability. The sophisticated synthesis of new compounds makes them almost more expensive than high-purity inorganic substances, therefore, the greatest practical prospects are the study and modification (optimization) of widely used and studied (more or less) compounds with high stability and the ability to integrate (not necessarily) into the developed technological processes. The best known are phthalocyanines, fullerenes, polythiophenes and polyarenes.

Fullerene-like materials

Graphite, diamond, and not universally recognized carbine were considered for a long time to be the main allotron states of carbon. They were used in many branches of industry and technology, including micro- and optoelectronics. Ten years before the end of the 20th century, new molecular forms of carbon were discovered first in space and then obtained in the laboratory - fullerenes and fullerene-like individual substances and materials. At the end of the last century, up to 1000 or more publications on fullerenes (their production, research and application) were published every year. It has been found that self-organization of fullerene structures occurs everywhere: in space, in natural processes on Earth, in industrial processes (ferrous metallurgy), and in laboratories. The properties and structure of these materials are so diverse and interesting that fullerene materials are beginning to be widely used in industry: from micro- and nanoelectronics to effective medicines.

The fullerene materials obtained and studied at the present time include the following:

· Fullerenes. They form molecular-crystalline solids, often due to the large size and high symmetry of their molecules - plastic crystals without a melting point. They are formed by molecules that are either spheres or ellipses, although other combinations are possible (hemispheres with carbon cylinders). Layered spheres or ellipses are possible ("oolitic" or "onion" structures). The size of the molecules of the main representative of fullerenes is 1 nm, and in solution the molecules have the properties of a Brownian particle;

· Carbon nanotubes. They are formed from graphite planes rolled up in different directions and closed at the ends with meshed carbon hemispheres. Such "graphite" nanotubes can be single-layered and multilayered. The latter can be converted by oxidation and etching into single-layer ones. Carbon nanotubes can have branches and bends. In this case, they lose their original "graphite" structure and are not called "graphite". Single-walled nanotubes have sizes from 1 to 10 nm in diameter and a length of 100-1000 nm or more, while multilayer ones have diameters and lengths 10-100 times larger. Solids can be formed from nanotube bundles or collinear (but shorter) formations;

· Filled fullerenes (endo-derivatives). The filling can be molecules of inert or other gases, small organic and inorganic molecules, metal atoms (alkaline, alkaline earth, lanthanides, etc.). Despite the difficulties in obtaining and the low yield of such derivatives, their inherent properties make it necessary to investigate their synthesis and possible applications. These derivatives, for the most part, have extremely low ionization potentials compared to metals, and, apparently, have metallic properties;

· Filled carbon nanotubes. In addition to the above, smaller diameter fullerenes can be used for filling;

· Inorganic nanotubes (, etc.).

The patent literature and applications of fullerene-like materials are extremely varied. Fullerene-like materials have a number of remarkable characteristics, including chemical resistance, high strength, stiffness, toughness, thermal conductivity, and (perhaps most importantly) electrical conductivity. Depending on the subtle features of molecular symmetry, fullerenes and nanotubes can be dielectrics, semiconductors, have metallic conductivity and high-temperature superconductivity. These properties, combined with their nanoscale geometry, make them near-ideal—perhaps even unique—materials for making electrical wires, superconducting compounds, or whole devices that might justifiably be called molecular electronics. The chemical assembly of elements of various schemes is favored by the properties of fullerene, which can form ions from +6 to -6 and, in various matrices, bonds with donors, acceptors, free radicals, and ions. Fullerenes can also be used to create means of molecular optoelectronics for femtosecond optical fiber transmission of information. The polymerization of fullerenes under electron beam or ionizing action makes it possible to obtain a new generation of resists.

Carbon nanotubes are used as needle probes in scanning probe microscopes and in field emission displays, in high-strength composite materials, and in electronic devices with short nanotube circuits that have been manipulated and assembled. The molecular nature of fullerene materials allows for the development of a chemical strategy for assembling these elements into usable structures, materials, and possibly even molecular electronic devices.

Structural nanomaterials

The use of modern structural materials is usually limited by the fact that an increase in strength leads to a decrease in ductility. Data on nanocomposites show that the reduction of structural elements and a deeper study of the physics of deformation processes that determine the plasticity of nanostructured materials can lead to the creation of new types of materials that combine high strength and plasticity.

An analysis of domestic and foreign studies conducted in recent years indicates the high promise of the following main areas in the development of structural materials: the manufacture of nanostructured ceramic and composite products of precise shape, the creation of nanostructured hard alloys for the production of cutting tools with increased wear resistance and impact strength, the creation of nanostructured protective thermal - and corrosion-resistant coatings, the creation of polymer composites with increased strength and low flammability with fillers from nanoparticles and nanotubes.

In laboratory studies samples of products from nanophase ceramics (density at the level of 0.98-0.99 of the theoretical value) based on aluminum oxides and a number of transition metals were obtained. It has been experimentally confirmed that dense nanostructured ceramics have increased plasticity at relatively low temperatures. The increase in plasticity with decreasing particle size is caused by the shear movement of nanocrystalline grains relative to each other when a load is applied. In this case, the absence of intergrain bond breaking is explained by the effective diffusion transfer of atoms in the near-surface layer of particles. In the future, increased plasticity means the possibility of superplastic molding of ceramic and composite products, which eliminates the need for labor- and energy-intensive finishing of high-hardness materials.

In recent years, nanocomposite cermet materials have been developed, in particular, based on and significantly superior in wear resistance, strength, and impact strength to analogues with a conventional microstructure. The increased operational characteristics of nanocomposite materials are due to the formation during sintering of specific continuous filamentous structures formed as a result of three-dimensional contacts between nanoparticles of different phases. The development and introduction into industrial production of the technology for creating nanocomposite products will contribute to solving the problem of manufacturing high-quality cutting tools.

An increase in the corrosion resistance of nanostructured coatings is primarily due to a decrease in the specific concentration of impurities on the grain surface as their size decreases. A cleaner surface provides a more uniform morphology and higher grain boundary corrosion resistance. Nanostructured coatings are characterized by ultrahigh strength. One of the main mechanisms of hardening is due to the effect of accumulation of dislocations near obstacles, which, with a decrease in grain size, are their boundaries. An important advantage of coatings with a nanoscale structure is the possibility of reducing residual stresses in them due to their increased plasticity, which makes it possible to produce coatings of millimeter thickness.

The use of inorganic fillers dispersed in the polymer matrix from nanosized powders can significantly increase the fire resistance of plastics, which is one of the main disadvantages when using them as structural materials, since the combustion products of polymers, as a rule, are toxic substances. The research results show that the reduction in combustibility can be brought to self-extinguishing of the flame. At the same time, nanosized powder fillers do not reduce the mechanical strength and machinability of materials. Polymer nanocomposites have a high ablative resistance, which opens up prospects for their use to protect the surface of products operated at high temperatures.

Nanoelectronics

Modern scientific and technological progress is undoubtedly determined by the development of electronics, which is based on achievements in various fields of fundamental sciences, mainly solid state physics, semiconductor physics, and solid state technology. Recent advances in science show that, in contrast to traditional microelectronics, whose potentialities will apparently be exhausted in the next decade, further development of electronics is possible only on the basis of fundamentally new physical and technological ideas.

Thus, over a number of decades, increasing the functional complexity and speed of systems was achieved by increasing the density of placement and reducing the size of elements, the principle of operation of which did not depend on their scale. When moving to element sizes of the order of tens or units of nanometers, a qualitatively new situation arises, consisting in the fact that quantum effects (tunneling, size quantization, interference effects) have a decisive influence on physical processes in nanostructures and the operation of devices based on them.

The creation of nanostructures in which the role of functional elements is performed by individual molecules is also promising. In the future, this will make it possible to use the principles of receiving and processing information implemented in biological objects (molecular nanoelectronics). New opportunities in increasing power, temperature and radiation resistance, expanding the frequency range, improving the ergonomic characteristics of devices open up a direction in which ideas and technological achievements of vacuum and solid-state electronics (vacuum nanoelectronics) are synthesized.

The creation of nanostructures is based on the latest technological advances in the design at the atomic level of solid surface and multilayer structures with a given electronic spectrum and the necessary electrical, optical, magnetic and other properties. The required band structure of such artificial materials is ensured by the choice of substances from which separate layers of the structure are made ("zone engineering"), the transverse dimensions of the layers (dimensional quantization), and by changing the degree of coupling between the layers ("wave function engineering"). Along with quantum-dimensional planar structures (two-dimensional electron gas in quantum wells, superlattices), one- and zero-dimensional quantum objects (quantum wires and dots) are being investigated, interest in which is associated with the hopes of discovering new physical phenomena and, as a consequence, obtaining new opportunities for effective control of electronic and light fluxes in such structures.

Nanotechnologies are designed to solve the following problems in electronics:

· a sharp increase in the performance of computing systems;

· a sharp increase in the throughput of communication channels;

· a sharp increase in the information capacity and quality of information display systems with a simultaneous reduction in energy costs;

· a sharp increase in the sensitivity of sensor devices and a significant expansion of the range of measured values, which is important, in particular, for environmental problems;

· creation of highly economical solid-state lighting devices;

· a significant increase in the proportion of the use of electronic and optoelectronic components in medical, biological, chemical, engineering and other technologies.

A sharp increase in the performance of computing systems necessary in connection with the transition of integrated circuit technology to the nanometer scale. In table. Table 1 shows a forecast for a decrease in the characteristic dimensions of memory ICs and processors (I TRS Roadmap 2002), in Table. 2 - the prospect of energy reduction per switching.

Table 1

	Year of production, nm	2003	2010	2013	2016
DRAM	1/2 Pitch
	1/2 Pitch
	Printed Gate Length
	Physical Gate Length

table 2

Year	2003	2010	2013	2016
Switching energy, femtoJ

Thus, the development of "traditional microelectronics" implies a transition to nanotechnology. The development of nanotechnology will make it possible to design fundamentally new IC elements, such as, for example, "single-electron" devices that consume extremely low switching energies, or ultra-fast bipolar transistors with bases several nanometers thick. Devices based on nanostructures are fundamentally necessary for reading information in the computing process due to extremely low signal levels. An example is magnetic reading devices based on the giant magnetoresistance effect that occurs in layered metallic magnetically ordered media with a layer thickness of several nanometers.

A sharp increase in the bandwidth of communication channels implies the creation of highly efficient emitting and photodetector devices for FOCL and microwave devices for the terahertz and subterahertz ranges. It should immediately be emphasized that efficient laser diodes for communication lines are a typical product of nanotechnology, since they are quantum-well nanoheterostructures with a characteristic layer thickness of several nanometers. Efficient photodetectors are also based on such semiconductor heterostructures. Further development of emitting and photoreceiving devices is inevitably associated with the development of nanotechnology of quantum dots - nanoregions in a semiconductor that limit the movement of electrons in three directions. Here we can expect the appearance of devices of a fundamentally new type, using quantum mechanical laws.

The same applies to solid-state microwave electronic devices. The transition to the nanolevel will significantly improve the characteristics of microwave transistors and create devices based on quantum mechanical effects (for example, resonant tunneling diodes and devices based on superlattices).

A sharp increase in the information capacity and quality of information display systems with a simultaneous reduction in energy costs associated with the development of several directions. First of all, these are monolithic and hybrid matrices of light emitting diodes (coherent and incoherent). And here, semiconductor sources based on nanostructures are the most efficient and multifunctional. Semiconductor lasers of medium and high power, made on the basis of nanostructures, are effective for use in projection systems for various purposes (including projection televisions). Nanostructured materials (for example, based on carbon nanotubes) are extremely promising for creating efficient cathodes for plasma panels of any area.

A sharp increase in the sensitivity of sensor devices and a significant expansion of the range of measured values both by improving the characteristics of already existing devices and devices in the transition to sizes at which quantum mechanical effects become significant, and by creating fundamentally new devices based on the ability to "calibrate" various objects (atomic clusters and molecules) in the nanometer size range and exploit the high surface sensitivity of nanostructured materials. An example of the use of nanotechnology for these purposes is the creation of lasers in the far and mid-IR ranges based on quantum semiconductor nanostructures, which make it possible to control atmospheric pollution with high sensitivity and accuracy.

Creating Highly Economical Solid State Lighting Products is the most important task of modern society. Lighting now consumes about 20% of the energy consumed in the world and the transfer of at least half of the lighting to highly economical semiconductor light sources based on nanostructures will reduce global energy costs by 10%.

A significant increase in the proportion of the use of electronic and optoelectronic components in medical, biological, chemical, engineering and other technologies. It is important to keep in mind several factors here. First of all, thanks to the ability to create substances and structures with a predetermined optical spectrum using nanotechnology, it is possible to “tune” radiation sources and receivers, which makes it possible to selectively influence biological and chemical processes and receive signals in the necessary spectral ranges to control such processes. Another important circumstance is that it is thanks to the use of nanostructures that it is possible to use very compact high-power sources of laser radiation. This will allow the development of high-precision, economical and environmentally friendly materials processing technologies. We emphasize that these same sources are very effective for use in medicine.

Nano- and microelectromechanics

The relevance of the direction

Progress in the development of nano- and microelectromechanical devices and systems promises the same revolution in technology that microelectronics has made in electronics. Microelectromechanics became an independent direction 15-20 years ago. The basis of this direction is the combination of surface micromachining, developed in microelectronic technology, with volumetric processing and the use of new materials and physical effects. The rapid growth of microelectromechanics, which is, in fact, an interdisciplinary direction, is associated primarily with the widespread use of microelectronic technologies with a honeycomb microstructure. This approach made it possible in a short time to create new three-dimensional structural elements - membranes, beams, cavities, holes with a large aspect ratio (caliber), through the use of so-called LiGA technologies based on synchrotron radiation, etc. This provided a breakthrough in the field of micromotors for microrobots, micropumps for microfluidics, ultrasensitive sensors of various physical quantities (pressure, acceleration, temperature, etc.), microoptics. So, micromechanical sensors in modern cars are the basis of security systems (airbags), monitoring the condition of wheels, suspension, etc. But the most prominent representative of microelectromechanical systems are scanning probe microscopes, which are the basis of not only a number of measuring systems in the nanometer range, but also the basis of technological devices for nanotechnology.

The transition to nanoelectromechanics is associated with the use of nanotechnology and new physical effects. Thus, when creating cavities, an important component of various devices, self-organizing processes (carbon nanotubes, porous membranes based on aluminum oxide) are increasingly being used. This allows to increase reproducibility, increase reliability, since the slightest dimensional changes associated with the use of traditional technologies lead to an exponentially strong change in parameters.

In developed foreign countries, much attention is paid to this area - research institutes are being created, training of specialists is being developed. In the USA, such well-known companies as Intel, MEMS Industry Group, and Sandia National Labs deal with these issues. The range of issues under consideration ranges from a splatter-free pen to wireless data transmission, optical weapon control devices and mini-satellites. The Advanced Research Agency of the US Department of Defense is implementing the Smart Dust program, aimed at creating subminiature devices capable of generating energy, monitoring the environment, accumulating and transmitting information.

Thus, the development of nano- and microelectromechanics is a necessary condition for the development of the foundations of nanotechnology.

Technological aspects of the development of nano- and microelectromechanical systems

Nanoimprinting(printing with a stamp). These are new group technologies, which are being developed instead of optical lithography, for obtaining a pattern with a record resolution of nm. Technologies make it possible to implement both obtaining a mask for further technological operations and functional structures.

Intelligent nanotechnological complexes based on scanning probe technology. High-vacuum complexes providing local modification of the surface (phase composition, potential and spatial relief, structural rearrangement) in the nm range. Modification is carried out due to field, mechanical and thermal influences, as well as due to the introduction of reactive media directly into the area of ​​influence under the probe. Multi-probe cartridges and precision multiple positioning devices (with nm accuracy) are needed to increase productivity.

Technologies of self-organization and self-assembly. As the size of nm decreases, the creation of ordered structures and single structures by traditional methods becomes a difficult task. From this point of view, various shaping structures (cavities) in which nanoelements can be created are especially important. An important role is also played by technologies for obtaining ordered nanotubes (especially carbon ones) and porous membranes based on aluminum oxide.

Technology for obtaining a pattern based on scanning probe microscopy with nm resolution due to the use of carbon nanotubes and precision positioners as probes.

Development of the element base of nano- and microelectromechanics

Nanoelements for direct conversion of electrical energy into mechanical energy with high efficiency. Static elements based on oriented nanotube bundles are many times more efficient than piezoelectric ones and can operate, for example, in physiological saline. Dynamic elements based on nanotubes provide switching in the picosecond range. Single-walled nanotubes with a large aspect ratio can move in liquid media due to wave-like motion. All this opens up great prospects for both technical and biomedical applications.

Filling nanocavities(including nanotubes) with alien atoms, molecules, clusters, fullerenes allows not only changing the characteristics of elements, but also creating one-dimensional crystals, storing and delivering certain components to the right place to create new elements using probe technologies. The filling of two-dimensional and three-dimensional nanoporous media makes it possible to create photonic crystals - the basis for optical switching devices of "no-threshold" lasers, ultrasensitive photodetectors. Of great interest to medicine is the grafting of organic complexes and DNA to nanotubes.

Ultra-sensitive sensors without intermediate energy conversion. They can be created because the frequency range of mechanical vibrations of nanoelements is close to the rotational and vibrational spectra of molecules.

Field emission effects along with quantum mechanical effects associated with charge transfer, play an increasing role in such nanoelements. Thus, the field emission thresholds for nanotubes are several orders of magnitude lower than those for conventional elements. This opens up the possibility of creating nanolamps combined with nanotransistors, which is important for information processing devices operating under extreme conditions and conditions of special effects.

Nanoelectromechanical devices and systems

Nanoelectromechanical terabit storage devices. Matrix multiprobe scanners in combination with regular media of nanoelements make it possible to create terabit memory devices with a density of up to 10 bit/cm 2 , which is necessary for new generation information processing systems.

Micro- and nano-optoelectromechanical systems. Controlled micromechanical mirror reflectors and diffraction gratings provide switching and selection of signals in wireless data transmission, in weapon control systems, microrobots, etc. with a transmission rate of 10 12 bps.

Microrobotics. Creation of microdevices capable of moving, collecting, storing and transmitting information, carrying out certain actions according to a given program or command. Development of micromotors, micropumps, microdrives.

Nano- and microelectromechanical sensors of various physical quantities(acceleration, pressure, temperature, humidity, size changes, speed of chemical and physical processes).

Flexible flat-panel displays and display devices.

Key Applications

Such areas of application of nano- and microelectromechanical devices and systems can be:

· information and computer technologies;

· mechanical engineering;

· biology and medicine;

· nanosystems for hazardous industries, nuclear power;

· nanosystems for weapons systems and space systems.

Diagnostics of nanostructures

The modern development of the physics and technology of solid-state nanostructures, which is manifested in the continuous transition of the topology of electronic equipment elements from submicron sizes to nanometer geometry, has required the development of new and improvement of existing diagnostic methods, as well as the creation of new types of equipment for the analysis of properties and processes in low-dimensional systems, in nanomaterials and in artificially created nanostructures. In this regard, special attention is paid to the development and application of complementary high-resolution methods for practical diagnostics and characterization of nanostructures that provide the most complete information about the main physical, physicochemical, and geometric parameters of nanostructures and the processes occurring in them.

Currently, there are a huge number of diagnostic methods, even more methods for studying the physical and physicochemical parameters and characteristics of solid and molecular structures. At the same time, obtaining nanostructures, low-dimensional systems, and new nanostructured materials with desired properties intended for use in modern electronics poses new diagnostic problems. To solve modern problems of diagnosing nanostructures, it is necessary to adapt traditional methods (equipment) to these problems, as well as the development of new, primarily local (up to 0.1 nm scales) methods for studying and analyzing the properties and processes inherent in objects of nanometer geometry and systems of reduced dimensionality.

Nanodiagnostics methods should be as nondestructive as possible and provide information not only about the structural properties of nanoobjects, but also about their electronic properties with atomic resolution. For the development of nanotechnologies, the ability to control atomic and electronic processes in situ with a high temporal resolution, ideally up to a time equal to or less than the period of atomic oscillations (up to 10 -13 s or less), is also decisive. It is also necessary to diagnose the electronic, optical, magnetic, mechanical and other properties of nanoobjects at the "nanoscopic" level. The impossibility of fully satisfying these requirements leads to the use of a set of methods for diagnosing nanoobjects, among which the following main groups of methods should be distinguished:

· high-resolution electron microscopy, which historically was the first method that really provides visualization of the structure of objects with atomic resolution. This method is adjoined by various modifications of electron microscopy, which provide chemical analysis of nanoobjects, in situ studies, surface-sensitive methods, such as reflective electron microscopy, slow electron microscopy, and others. In many cases, high resolution electron microscopy is the only source of information on the internal structure and interface structure of such nanoobjects as quantum wells and quantum dots;

· methods of scanning electron microscopy, which come close in resolution to atomic resolution, while retaining the possibility of obtaining information without a significant (destructive) effect on the objects under study, obtaining various information about the chemical composition of nanoobjects, their electrical (induced current method), optical (cathodoluminescence) and others properties. To obtain information about the volume of nanoobjects, methods of electron tomography have been developed;

· scanning tunneling microscopy, which is a surface-sensitive method for visualizing the atomic structure of solids; conducting spectroscopic studies with atomic resolution, together with the use of in situ experiments at elevated and low temperatures, the use of other methods of probe microscopy and the possibility of manipulation at the level of individual atoms, makes these methods the most important tool for nanotechnology and nanodiagnostics;

· X-ray diffraction methods, especially using the high luminosity of synchrotron sources, they provide unique information about the atomic structure of nanoobjects without destroying them;

· methods of electron spectroscopy for chemical analysis, Auger electron spectroscopy, methods of photoelectron spectroscopy, Romanov and IR spectroscopy, photoluminescence, which are actively developed with increasing resolution, which makes these methods very useful in the diagnosis of nanoobjects.

Further development of various diagnostic methods (in particular, diagnostics built into the technology), taking into account the specifics of nanoobjects and their characteristic sizes, is an integral part of the development of high technologies for obtaining and analyzing the properties of new generation nanostructures. At the same time, the formation of complex methods for practical diagnostics is dictated both by the technological problems of obtaining nanostructures and creating the next generation of electronic and optical devices (transistors, lasers, etc.) on their basis, and by their specific physical, physicochemical, and topological properties, which often do not fit into the framework of standard ideas about the properties of matter.

Conclusion

In conclusion, it is necessary to emphasize once again that the development of the science of nanostructures and, above all, of quantum nanostructures (nanophysics) and nanotechnologies will make it possible to obtain nanomaterials with qualitatively new properties. The development of nanoelectronics and nanomechanics will serve as the basis for a qualitatively new stage in the development of the latest information technologies, communications, in solving problems of a qualitatively new standard of living, etc. Success in the development of these areas will be determined, in fact, by solving two main problems: the development of reliable methods for creating nanomaterials and nanoobjects with the required properties, including the use of atom-by-atom assembly methods and self-organization effects; development of new and development of existing methods of nanodiagnostics with atomic resolution. Modern progress in the field of nanotechnology allows us to hope that many problems will be solved in the near future.

Nanotechnology is a field of fundamental and applied science and technology that deals with a combination of theoretical justification, practical methods of research, analysis and synthesis, as well as methods for the production and use of products with a given atomic structure by controlled manipulation of individual atoms and molecules.

History

Many sources, primarily English-speaking, the first mention of the methods that will later be called nanotechnology, is associated with Richard Feynman's famous speech “There's Plenty of Room at the Bottom”, made by him in 1959 at the California Institute of Technology at the annual meeting of the American Physical Society. Richard Feynman suggested that it was possible to mechanically move single atoms with a manipulator of the appropriate size, at least such a process would not contradict the physical laws known today.

He suggested doing this manipulator in the following way. It is necessary to build a mechanism that would create its own copy, only an order of magnitude smaller. The created smaller mechanism must again create its copy, again an order of magnitude smaller, and so on until the dimensions of the mechanism are commensurate with the dimensions of the order of one atom. At the same time, it will be necessary to make changes in the structure of this mechanism, since the forces of gravity acting in the macrocosm will have less and less influence, and the forces of intermolecular interactions and van der Waals forces will increasingly affect the operation of the mechanism.

The last stage - the resulting mechanism will assemble its copy from individual atoms. In principle, the number of such copies is unlimited, it will be possible to create an arbitrary number of such machines in a short time. These machines will be able to assemble macrothings in the same way, atom-by-atom assembly. This will make things an order of magnitude cheaper - such robots (nanorobots) will need to be given only the required number of molecules and energy, and write a program to assemble the necessary items. Until now, no one has been able to refute this possibility, but no one has yet managed to create such mechanisms. In the course of a theoretical study of this possibility, hypothetical doomsday scenarios have emerged that suggest that nanorobots will absorb the entire biomass of the Earth, carrying out their self-reproduction program (the so-called “gray goo” or “gray goo”).

The first assumptions about the possibility of studying objects at the atomic level can be found in the book "Opticks" by Isaac Newton, published in 1704. In the book, Newton expresses the hope that the microscopes of the future will someday be able to explore "the mysteries of corpuscles."

The term "nanotechnology" was first used by Norio Taniguchi in 1974. He called this term the production of products with a size of several nanometers. In the 1980s, the term was used by Eric K. Drexler in his books Engines of Creation: The Coming Era of Nanotechnology and Nanosystems: Molecular Machinery, Manufacturing, and Computation.

What can nanotechnology do?

Here are just a few of the areas where nanotechnology promises breakthroughs:

The medicine

Nanosensors will ensure progress in the early diagnosis of diseases. This will increase the chances of recovery. We can beat cancer and other diseases. Old cancer drugs destroyed not only diseased cells, but also healthy ones. With the help of nanotechnology, the drug will be delivered directly to the diseased cell.

DNA nanotechnologies- use the specific bases of DNA molecules and nucleic acids to create clearly defined structures on their basis. Industrial synthesis of molecules of drugs and pharmacological preparations of a well-defined shape (bis-peptides).

In early 2000, thanks to the rapid progress in the technology of manufacturing nano-sized particles, an impetus was given to the development of a new field of nanotechnology - nanoplasmonics. It turned out to be possible to transmit electromagnetic radiation along a chain of metal nanoparticles by excitation of plasmon oscillations.

Building

Nanosensors of building structures will monitor their strength, detect any threats to integrity. Objects built using nanotechnology can last up to five times longer than modern structures. Homes will adapt to the needs of residents, keeping them cool in summer and warm in winter.

Energy

We will be less dependent on oil and gas. Modern solar panels have an efficiency of about 20%. With the use of nanotechnology, it can grow by 2-3 times. Thin nanofilms on the roof and walls can provide energy to the whole house (if, of course, there is enough sun).

mechanical engineering

All bulky equipment will be replaced by robots - easily controlled devices. They will be able to create any mechanisms at the level of atoms and molecules. For the production of machines, new nanomaterials will be used that can reduce friction, protect parts from damage, and save energy. These are far from all the areas in which nanotechnologies can (and will!) be applied. Scientists believe that the emergence of nanotechnology is the beginning of a new scientific and technological revolution that will greatly change the world in the 21st century. However, it is worth noting that nanotechnologies do not enter the real practice very quickly. Not many devices (mostly electronics) work "with nano". This is partly due to the high cost of nanotechnology and the not very high return on nanotechnology products.

Probably, in the near future, with the help of nanotechnologies, high-tech, mobile, easily controlled devices will be created that will successfully replace the automated, but difficult to manage and bulky equipment of today. So, for example, over time, computer-controlled biorobots will be able to perform the functions of the current bulky pumping stations.

• DNA computer- a computing system that uses the computational capabilities of DNA molecules. Biomolecular computing is a collective name for various techniques related to DNA or RNA in one way or another. In DNA computing, data is not represented in the form of zeros and ones, but in the form of a molecular structure built on the basis of the DNA helix. The role of software for reading, copying and managing data is performed by special enzymes.
• Atomic force microscope– high-resolution scanning probe microscope, based on the interaction of the cantilever needle (probe) with the surface of the sample under study. Unlike a scanning tunneling microscope (STM), it can examine both conductive and non-conductive surfaces even through a liquid layer, which makes it possible to work with organic molecules (DNA). The spatial resolution of an atomic force microscope depends on the size of the cantilever and the curvature of its tip. The resolution reaches atomic horizontally and significantly exceeds it vertically.
• Antenna oscillator- On February 9, 2005, an oscillator antenna with a size of about 1 micron was obtained in the laboratory of Boston University. This device has 5,000 million atoms and is capable of oscillating at a frequency of 1.49 gigahertz, which allows you to transfer huge amounts of information with it.

10 Nanotechnologies With Amazing Potential

Try to remember some canonical invention. Probably, someone now imagined a wheel, someone an airplane, and someone an iPod. And how many of you have thought about the invention of a completely new generation - nanotechnology? This world is little known, but it has incredible potential that can give us really fantastic things. The amazing thing is that the direction of nanotechnology did not exist until 1975, even though scientists began working in this area much earlier.

The human naked eye is able to recognize objects up to 0.1 mm in size. Today we will talk about ten inventions that are 100,000 times smaller.

Electrically conductive liquid metal

With electricity, a simple liquid metal alloy of gallium, iridium, and tin can be made to form complex shapes or wind circles inside a Petri dish. It can be said with some degree of probability that this is the material from which the famous T-1000 series cyborg was created, which we could see in Terminator 2.

“A soft alloy behaves like a smart form, capable of self-deforming if necessary, taking into account the changing surrounding space through which it moves. Just like a cyborg from a popular sci-fi movie could do, ”says Jin Li from Tsinghua University, one of the researchers involved in this project.

This metal is biomimetic, that is, it mimics biochemical reactions, although it is not itself a biological substance.

This metal can be controlled by electrical discharges. However, he himself is able to move independently, due to the emerging load imbalance, which is created by the difference in pressure between the front and back of each drop of this metal alloy. And although scientists believe that this process may be the key to converting chemical energy into mechanical energy, molecular material is not going to be used to build evil cyborgs in the near future. The whole process of "magic" can only take place in a sodium hydroxide solution or saline solution.

Nanoplasters

Researchers at the University of York are working to create special patches that will be designed to deliver all the necessary drugs into the body without any use of needles and syringes. Plasters of quite normal size are glued to the hand, delivering a certain dose of drug nanoparticles (small enough to penetrate through the hair follicles) inside your body. Nanoparticles (each less than 20 nanometers in size) will find harmful cells on their own, kill them and be removed from the body along with other cells as a result of natural processes.

Scientists note that in the future, such nanoplasters can be used in the fight against one of the most terrible diseases on Earth - cancer. Unlike chemotherapy, which in such cases is most often an integral part of the treatment, nanopatch will be able to individually find and destroy cancer cells while leaving healthy cells intact. The nanopatch project was named NanJect. It is being developed by Atif Syed and Zakaria Hussain, who in 2013, while still students, received the necessary sponsorship as part of a crowdsourcing fundraising campaign.

Nanofilter for water

When this film is used in combination with a thin stainless steel mesh, oil is repelled and the water in the area becomes pristine.

Interestingly, nature itself inspired scientists to create a nanofilm. Lotus leaves, also known as water lilies, have the opposite of nanofilms: instead of oil, they repel water. This is not the first time scientists have peeped at these amazing plants for their no less amazing properties. The result of this, for example, was the creation of superhydrophobic materials in 2003. As for the nanofilm, researchers are trying to create a material that mimics the surface of water lilies and enrich it with molecules of a special cleanser. The coating itself is invisible to the human eye. Production will be inexpensive: approximately $1 per square foot.

Submarine Air Purifier

It is unlikely that anyone thought about what kind of air the crews of submarines have to breathe, except for the crew members themselves. Meanwhile, the purification of air from carbon dioxide must be carried out immediately, since in one voyage through the light crews of the submarine the same air has to pass hundreds of times. To purify the air from carbon dioxide, amines are used, which have a very unpleasant odor. To address this issue, a cleaning technology was created, called SAMMS (an acronym for Self-Assembled Monolayers on Mesoporous Supports). It proposes the use of special nanoparticles placed inside ceramic granules. The substance has a porous structure, due to which it absorbs excess carbon dioxide. The different types of SAMMS cleanings interact with different molecules in air, water, and earth, but all of these cleaning options are incredibly effective. Just one tablespoon of these porous ceramic granules is enough to clean an area equal to one football field.

Nanoconductors

Researchers at Northwestern University (USA) figured out how to create an electrical conductor at the nanoscale. This conductor is a solid and strong nanoparticle that can be tuned to carry electric current in various opposite directions. The study shows that each such nanoparticle is able to emulate the operation of "a rectifier, switches and diodes." Each 5 nanometer-thick particle is coated with a positively charged chemical and surrounded by negatively charged atoms. Applying an electrical discharge reconfigures the negatively charged atoms around the nanoparticles.

The potential of the technology, according to scientists, is unprecedented. Based on it, you can create materials that "are capable of independently changing for certain computer computing tasks." The use of this nanomaterial will actually "reprogram" the electronics of the future. Hardware upgrades will be as easy as software upgrades.

Nanotech Charger

When this thing is created, you will no longer need to use any wired chargers. The new nanotechnology works like a sponge, only it absorbs non-liquid. It sucks kinetic energy from the environment and sends it directly to your smartphone. The basis of the technology is the use of a piezoelectric material that generates electricity while in a state of mechanical stress. The material is endowed with nanoscopic pores that turn it into a flexible sponge.

The official name of this device is "nanogenerator". Such nanogenerators could one day become part of every smartphone on the planet, or part of the dashboard of every car, and perhaps even part of every pocket of clothing - gadgets will be charged right in it. In addition, the technology has the potential to be used at a larger scale, for example, in industrial equipment. At least that's what researchers at the University of Wisconsin-Madison think, who created this amazing nanosponge.

artificial retina

The Israeli company Nano Retina is developing an interface that will directly connect to the neurons of the eye and transmit the result of neural simulation to the brain, replacing the retina and returning people to sight.

An experiment on a blind chicken showed hope for the success of the project. The nanofilm allowed the chicken to see the light. True, the final stage of the development of an artificial retina to restore vision to people is still far away, but the progress in this direction cannot but rejoice. Nano Retina is not the only company involved in such developments, but it is their technology that is currently seen as the most promising, efficient and adaptive. The last point is the most important since we are talking about a product that will integrate into someone's eyes. Similar developments have shown that solid materials are unsuitable for such applications.

Since the technology is developed at the nanotechnological level, it eliminates the use of metal and wires, as well as avoiding the low resolution of the simulated image.

Glowing clothes

Shanghai scientists have developed reflective threads that can be used in the production of clothing. The basis of each thread is a very thin stainless steel wire, which is coated with special nanoparticles, a layer of electroluminescent polymer, and a protective sheath of transparent nanotubes. The result is very light and flexible threads that can glow under the influence of their own electrochemical energy. At the same time, they operate at much lower power than conventional LEDs.

The disadvantage of the technology lies in the fact that the “light reserve” of the threads is still enough for only a few hours. However, the developers of the material optimistically believe that they will be able to increase the "resource" of their product at least a thousand times. Even if they succeed, the solution to another drawback is still in question. Most likely, it will be impossible to wash clothes based on such nanothreads.

Nanoneedles for the restoration of internal organs

The nanoplasters we talked about above are designed specifically to replace needles. What if the needles themselves were only a few nanometers in size? In this case, they could change our understanding of surgery, or at least significantly improve it.

More recently, scientists have conducted successful laboratory tests on mice. With the help of tiny needles, researchers were able to inject nucleic acids into rodent organisms that promote the regeneration of organs and nerve cells and thereby restore lost performance. When the needles perform their function, they remain in the body and after a few days completely decompose in it. At the same time, scientists did not find any side effects during operations to restore the blood vessels of the muscles of the back of rodents using these special nanoneedles.

If we take into account human cases, then such nanoneedles can be used to deliver the necessary funds to the human body, for example, in organ transplantation. Special substances will prepare the surrounding tissues around the transplanted organ for rapid recovery and eliminate the possibility of rejection.

3D chemical printing

University of Illinois chemist Martin Burke is a real Willy Wonka from the world of chemistry. Using a collection of "building material" molecules for various purposes, he can create a huge number of different chemicals, endowed with all sorts of "amazing and yet natural properties." For example, one such substance is ratanin, which can only be found in a very rare Peruvian flower.

The potential for synthesizing substances is so huge that it will make it possible to produce molecules used in medicine in the creation of LED diodes, solar cell cells and those chemical elements that even the best chemists on the planet took years to synthesize.

The capabilities of the current prototype of a three-dimensional chemical printer are still limited. He is able to create only new drugs. However, Burke hopes that one day he will be able to create a consumer version of his amazing device, which will have much more capabilities. It is quite possible that in the future such printers will act as a kind of home pharmacists.

Does nanotechnology pose a threat to human health or the environment?

There is not so much information about the negative impact of nanoparticles. In 2003, one study showed that carbon nanotubes could damage the lungs in mice and rats. A 2004 study showed that fullerenes can accumulate and cause brain damage in fish. But both studies used large doses of the substance under unusual conditions. According to one of the experts, chemist Kristen Kulinowski (USA), "it would be advisable to limit the impact of these nanoparticles, despite the fact that currently there is no information about their threat to human health."

Some commentators also argue that the widespread use of nanotechnology may lead to social and ethical risks. So, for example, if the use of nanotechnology initiates a new industrial revolution, it will lead to job losses. Moreover, nanotechnologies can change the idea of ​​a person, since their use will help prolong life and significantly increase the body's resistance. “No one can deny that the widespread use of mobile phones and the Internet has brought about enormous changes in society,” says Kristen Kulinowski. “Who dares to say that nanotechnology will not have a greater impact on society in the coming years?”

Place of Russia among the countries developing and producing nanotechnologies

The world leaders in terms of total investment in the field of nanotechnology are the EU countries, Japan and the United States. Recently, Russia, China, Brazil and India have significantly increased investments in this industry. In Russia, the volume of financing within the framework of the program "Development of the Nanoindustry Infrastructure in the Russian Federation for 2008-2010" will amount to 27.7 billion rubles.

In the latest (2008) report of the London-based research firm Cientifica, called the “Nanotechnology Outlook Report,” the following is written about Russian investments: “Although the EU still ranks first in terms of investment, China and Russia have already overtaken the United States.”

There are such areas in nanotechnology where Russian scientists became the first in the world, having obtained results that laid the foundation for the development of new scientific trends.

Among them are the production of ultrafine nanomaterials, the design of single-electron devices, as well as work in the field of atomic force and scanning probe microscopy. Only at a special exhibition held within the framework of the XII St. Petersburg Economic Forum (2008), 80 specific developments were presented at once. Russia already produces a number of nanoproducts that are in demand on the market: nanomembranes, nanopowders, nanotubes. However, according to experts, Russia is ten years behind the United States and other developed countries in the commercialization of nanotechnological developments.

Nanotechnology in art

A number of works by the American artist Natasha Vita-Mor deal with nanotechnological topics.

In modern art, a new direction "nanoart" (nanoart) has arisen - a type of art associated with the creation by the artist of sculptures (compositions) of micro- and nano-sizes (10 −6 and 10 −9 m, respectively) under the influence of chemical or physical processes of processing materials , photographing the obtained nano-images using an electron microscope and processing black-and-white photographs in a graphics editor.

In the well-known work of the Russian writer N. Leskov “Lefty” (1881), there is a curious fragment: “If,” he says, “there was a better small scope, which magnifies five million, so you would deign,” he says, “to see that on each horseshoe, the master's name is displayed: which Russian master made that horseshoe. An increase of 5,000,000 times is provided by modern electron and atomic force microscopes, which are considered the main tools of nanotechnology. Thus, the literary hero Lefty can be considered the first "nanotechnologist" in history.

Feynman's 1959 lecture "There's a lot of space down there" on the ideas of how to create and use nanomanipulators coincide almost textually with the science fiction story "Microhands" by the famous Soviet writer Boris Zhitkov, published in 1931. Some negative consequences of the uncontrolled development of nanotechnologies are described in the works of M. Crichton ("Swarm"), S. Lem ("Inspection on the spot" and "Peace on Earth"), S. Lukyanenko ("Nothing to share").

The protagonist of the novel “Transman” by Y. Nikitin is the head of a nanotechnology corporation and the first person to experience the action of medical nanorobots.

In the sci-fi series Stargate SG-1 and Stargate Atlantis, one of the most technologically advanced races are two races of "replicators" that arose as a result of unsuccessful experiments with the use and description of various applications of nanotechnology. In the film The Day the Earth Stood Still, starring Keanu Reeves, an alien civilization passes a death sentence on humanity and almost destroys everything on the planet with the help of self-replicating nano-replicant beetles, devouring everything in its path.

As a result of mastering the materials of this section, students should:

know

• basic concepts of nanotechnology, prospects for the development of nanoscience and nanotechnology;
• technologies for obtaining nanoparticles;

be able to

Use nanomaterials and nanotechnologies in the production of modern and advanced products;

own

• skills in analyzing the results of research in the field of nanotechnology;
• methods for studying nanomaterials.

BASIC CONCEPTS AND DEFINITIONS

History of nanotechnology. Basic concepts

The development of this new direction in science and technology has already become a priority task in many countries, including Russia. To solve the most complex problems of practical implementation of the emerging opportunities based on nanotechnologies, governments and businesses allocate huge funds, create special programs, projects and scientific coordinating centers for nanotechnologies. The number of scientific publications in this area has increased significantly in the world. Information on nanomaterials and nanotechnologies is included in the curricula of technical universities, some of them have begun training specialists in a new intensively developing scientific direction, on the basis of which amazing results have already been obtained in almost all spheres of human activity, and the future promises even more striking achievements. comparable to the most fantastic ideas.

It is obvious that a vast area of ​​science and technology in the XXI century. will be associated with the concept of "nanotechnology". If the word "techno" in Greek ( technology) means art, skill, craft, and "logy" (logos)- science, the word "nano" is also of Greek origin ( nanos) and means dwarf. Already now such terms as "nanophysics", "nanochemistry", "nanoporous", "nanocrystalline", "nanocomposite materials" etc. are in use.

Indeed, nano means just one billionth (10 9) of a meter - a nanometer (nm). This value can only be imagined speculatively. For example, 1 nm is the order of the size of an atom, a molecule; a thread of this size is several tens of thousands of times thinner than a human hair.

Nanotechnology, thus, can be defined as a set of methods for producing products with a given atomic structure by manipulating atoms and molecules.

At the same time, it should be noted that the terminology in the field of nanomaterials, to a certain extent, is only being formed and established. Thus, there is an approach to the definition of nanoparticles by their geometric parameters. In particular, particles with a size of 1–100 nm are classified as nanostructured. The limit of 100 nm was chosen based on the fact that starting from this size and below, special physical, mechanical and chemical properties of the material, including strength, hardness, etc., are noticeably manifested.

There are other approaches that take into account the role of numerous interfaces, while taking into account their volume fraction in the total amount of material. Some researchers rely in the classification of nanomaterials on special physical phenomena that manifest themselves at a certain particle size. However, the most common, and therefore accepted, definition is: nanomaterials- these are materials containing structural elements, the geometric dimensions of which do not exceed 100 nm in at least one dimension, and possessing qualitatively new properties, functional and operational characteristics.

There are also other terms in the literature: "ultradisperse materials", "ultradispersed systems", "nanostructural materials", "nanocrystalline materials".

Existing nanomaterials can be conditionally divided into several groups:

• a) materials (solid bodies) with dimensions of at least one coordinate less than 100 nm;
• b) materials in the form of micro-products ranging in size from 1 micron to 1 mm;
• c) bulk nanomaterials with dimensions of several millimeters. However, they consist of nanosized elements with a grain size of 1 - 100 nm;
• d) composite nanostructured materials. In such composites, various types of nanoparticles are modifiers.

The history of the development of nanotechnology can be traced back to ancient times. Indeed, the very assumption that all substances consist of the smallest particle called an atom was already a necessary step in the subsequent implementation of the ideas of nanotechnology. And he did this by introducing the concept of "atom", the Greek philosopher Democritus 2400 years ago. The American physicist Richard Feynman (1959) substantiated the idea of ​​creating material objects directly from atoms by manipulating them. In 1974, the Japanese physicist Porio Toniguchi introduced the concept of "nanotechnology" into scientific circulation.

In Russia, theoretical research in the field of nanotechnologies practically corresponded to the international level. There was a certain lag in the development of domestic precision equipment for research in this area. Progress in the accelerated development of nanotechnologies was precisely associated with the creation of a unique technique that makes it possible to study the microcosm with previously unknown possibilities. Even the most powerful electron microscopes that existed made it possible to distinguish atomic lattices, but it was necessary to see atoms - only then it was possible to engage in nanoscience.

In 1981, G. Bining and G. Roppr based on the so-called tunnel effect built a scanning tunneling microscope (STM) and with its help obtained an image of the surface of gold, silicon with atomic resolution. The STM is equipped with the thinnest conductive probe needle. The probe moves at a distance of approximately 0.5 nm above the surface under study. A constant small voltage is applied to the probe, due to which a tunneling current arises. Further, a small change in the distance between the probe and the surface of the metal under study leads to a significant change in the current value, which characterizes the sensitivity of the STM. The tracking system scans the surface so that the probe continuously tracks its topography. The accuracy of movements during scanning reaches thousandths of a nanometer. Such accuracy is achieved by using a special mechanical manipulator made of piezoceramic material.

The scanning tunneling microscope turned out to be a very necessary and thin tool for studying nanoscale objects. For his invention in 1985, scientists were awarded the Nobel Prize. However, it could be used to study materials that conduct electric current, which was a rather serious limitation for researchers.

In 1986, the next generation atomic force microscope (ACM) was created in the IBM laboratory (branch in Zurich, Switzerland). It is based on the use of interatomic bonds. When the probe (diamond needle) moves over the surface of the object under study, an interaction force arises between the probe and the surface.

When the thinnest needle approaches the atom, the forces of attraction first increase, and with further approach, even repulsion. Sensitive sensors transmit this effect to a computer, in which the signal is converted into a visible image. Such a microscope, in contrast to the ACM, is a universal tool for studying materials; it has found wider application.

Introduction.

A number of nanoobjects have been known and used for a long time. These include: colloids, fine powders, thin films.

1) R. Feynman is a Nobel laureate. "As far as I can see, the principles of physics do not prohibit the manipulation of individual atoms" 1959

2) 1996 R. Young proposed the idea of ​​piezo motors, which now provide precision movement of nanotechnology tools with an accuracy of 0.01 Å. Å=

3) In 1974, Norio Taniguchi first used the term "nanotechnology"

4) In 1982-1985 German professor G. Gleiter proposed the concept of solid state nanostructure.

5) In 1985 a team of scientists Robert Curl, Harold Kroto, Richard Smalley discovered fullerenes and created the theory of CNTs, which were experimentally obtained in 1991.

6) In 1982, G. Bining and G. Rohrer created the first scanning tunneling microscope (STM).

7) In 1986, a scanning atomic force microscope appeared.

8) In 1987-1988, the principle of operation of the first nanotechnological installation was demonstrated, which made it possible to manipulate individual atoms. (IN THE USSR)

E. Drexler - generalized all knowledge about nanotechnology, defined the concept of self-replicating molecular robots, which were supposed to assemble and decompose, record information into memory at the atomic level, save self-reproducing programs and implement them.

9) In 1990 With the help of STM, 3 letters were drawn by IBM. They were drawn with Xe atoms (35 atoms) on a flat face of a nickel crystal.

To date, technological methods of the so-called. the harnessing of atoms on surfaces and the formation of various combinations of atoms in the volume - at room temperature.

The most real output of nanotechnology is what is called the self-assembly of atomic structures. The task of modern nanotechnology is to find natural laws that would ensure the assembly of atomic structures.

The concept of nanoobject, nanomaterial, nanotechnology.

Nano - "". Thus, objects that have a size measured in nm in at least one dimension fall into the scope of nanotechnology. In reality, the range of objects under consideration is much wider - from the size of a single atom to a conglomerate of resp. (organic molecules that contain more than 10 9 atoms larger than 1 micron in 1.2 or 3 dimensions. atoms, which causes the manifestation of a discrete atomic-molecular structure of matter or quantum laws of its behavior.

1) Definition of a nanoobject. Any physical object with ng-meter dimensions in 1x, 2x, 3x coordinates of space (soon possible in time as well).

2) Definition of a nanoobject. A nanoobject is any ethereal object in which the number of near-surface atoms is comparable to or exceeds the number of atoms in the volume.

3) Definition of a nanoobject. A nanoobject is an object with dimensions in 1 or more coordinates, comparable to the de Broglie wavelength for an electron. (In 1924, the physicist de Broglie said that wave-particle duality for photons is inherent in any particle in nature). , where h is Planck's constant, p is momentum. Electron - has the largest de Broglie wave.

4) Definition of a nanoobject. Objects are named, which in their dimension are less than the critical size of the event. (the size of comparisons with the polarization radius of one or another critical phenomenon, the mean free path of electrons, the size of the magnetic domain, the size of the nucleation of the solid phase).

5) Definition of a nanoobject. A nano-object is an object with a size of less than 100 nm in at least 1 of 3 spatial dimensions. 100nm is the de Broglie wavelength for an electron in p/p.

Nanomaterials are called as nanoobjects themselves (if they are used for the manufacture of devices and devices for various technical purposes, as well as materials in which nanoobjects are used to form certain properties in these materials or nanostructured materials. The concept of "nanotechnology" is closely related to the concept of "nanomaterials".

The term "technology" refers to three concepts:

1) technological process
2) set of technological documentation

3) A scientific discipline that studies the pattern that accompanies processing processes and products.

Nanotechnology is a scientific discipline that studies patterns in the processing and application of nanomaterials.

Physical reasons for the specifics of nanoparticles and nanomaterials.

1) In nanoobjects, the number of near-surface or grain-boundary atoms becomes comparable to the number of atoms. Located in volume.

2) Atoms located on the surface, also in the nodes of ledges and steps, have a small number of completed bonds. Unlike atoms that are in the volume of a solid body. This leads to a different increase in the chemical and catalytic activity of nanoobjects and monostructured materials. In addition, migration from carbon atoms occurs much faster along the surface; an increase in the rate of diffusion migration, recrystallization, as well as sorption capacity, etc.

3) For nanoobjects, the image forces of linear and surface tension are much stronger than for nanoobjects, because when moving away from the surface in the volume of a solid, these forces are significantly weakened. The magnitude of these forces leads to the purification of the volume of the nanoobject by the forces of defects in the crystal structure. A nanoobject has a more perfect crystal structure than a nanoobject.

The image forces got their name from the method of calculating electric fields.

4) In nanoobjects, size effects due to scattering, recombination and reflection at the boundaries of objects (we are talking about the movement of microparticles) are of great importance.

In any transfer phenomenon (electric current, thermal conductivity, plasticity, deformation, etc.)

Carriers can be assigned a certain effective mean free path when the size of the object>>carrier mean free path, the process of scattering and loss of carriers weakly depends on the geometry of the object. If the size of the object is comparable to the mean free path of the carrier, then these processes are more intense and they strongly depend on the geometry of the sample.

5) The size of nanoparticles is comparable to or smaller than the size of the nucleus of a new phase, domain, dislocation loop, etc. This leads to a radical decrease in the magnetic properties (Fe nanoparticle does not have magnetic properties), dielectric properties, and strength properties of nanoobjects and nanomaterials compared to macroobjects.

6) For a small number of atoms of matter, surface reconstruction, self-organization, and self-assembly are characteristic. those. when an atom is combined into a cluster, geometric structures are formed, which can later be used to solve technical problems

Figure 1- Force of interaction between atoms.

7) Quantum laws of behavior of various elementary particles (electrons) are manifested in nanoobjects. From the standpoint of quantum mechanics, an electron can be represented by a wave describing the corresponding wave functions. The propagation of this wave in a solid body is controlled by the effects associated with the so-called. quantum limitation (wave interference, the possibility of tunneling through potential barriers). For metallic materials, the restrictions imposed by the wave nature of elementary particles are not relevant yet, because for them (for electrons) the de Broglie wave λe< 1мм, число составляет несколько атомарных размеров. А в п/п эффективная масса электрона и его скорость движения таковы, что длины волны де Бройля для электрона λe может составлять от 10 до 100 мм. Причем, размеры формируемых структур а п/п уже соизмеримы с данными величинами. Современные микропроцессоры (флэш память) || расстояние между контактами от 0.03мкм до 30мкм.

8) As the dimension of the nanoobject decreases, the degree of discretization of the energy spectrum of electrons increases. For a quantum dot (an object consisting, literally, of several atoms), electrons acquire a spectrum of allowed energies that is practically similar to a single atom.

CLASSIFICATION OF NANOOBJECTS.

The dimension of a nanoobject is the basis for the classification of nanoobjects.

According to the dimension, there are:

1) 0-D nano-objects - those in which all 3 spatial dimensions lie in the nanometer range (roughly: all 3 dimensions<100нм)

Such an object in the macroscopic sense is zero-dimensional and therefore, from the point of view of electronic properties, such objects are called quantum dots. In them, the de Broglie wave is larger than any spatial dimension. Quantum dots are used in laser engineering, optoelectronics, photonics, sensorics, etc.

2) 1-D nano-objects are those objects that have nanometer dimensions in two dimensions, and in the third - macroscopic size. These include: nanowires, nanofibers, single-walled and multi-walled nanotubes, organic macromolecules, incl. double strands of DNA.

3) 2-D nano-objects are those that have a nanometer size in only one dimension, and in the other two this size will be macroscopic. Such objects include: thin near-surface layers of a homogeneous material: films, coatings, membranes, multilayer heterostructures. Their quasi-two-dimensionality makes it possible to change the properties of the electron gas, the characteristics of electronic transitions (p-n transitions), etc. It is 2-D nano-objects that make it possible to come up with a basis for the development of a fundamentally new element base of radio electronics. This will be nanoelectronics, nanooptics, etc.

Currently, 2-D nanoobjects most often serve as all kinds of anti-fraction, anti-corrosion, etc. coatings. They are also of great importance for the creation of various types of membranes in molecular filters, sorbents, etc.

CLASSIFICATION OF NANOMATERIALS.

Given the fact that currently known nanomaterials have come to modern nanotechnologies from various fields of science and technology, an acceptable unified classification, on any basis, simply does not exist.

Nanomaterials:

Bulk nanostructured materials

Nanoclusters, nanoparticles, nanopowders

Multilayer nanofilms, multilayer nanostructures, multilayer nanocoatings.

Functional (smart) nanomaterials

Nanoporous

Fullerenes and their derivatives nanotubes

Biological and biocompatible materials

Nanostructured liquids: colloids, gels, suspensions, polymer composites

Nanocomposites.

NANOPARTICLES, NANOPOWDS

The first nanoparticles were created by man unintentionally, accidentally, in various technological processes. At present, they began to be designed and produced on purpose, which laid the foundation for nanotechnology. The development of nanotechnology has led to a fundamental revision of some fundamental principles:

Path " top down"– the general paradigm of nanotechnology (excess is cut off from the workpiece)

Nanotechnology offers a way upwards"- from small to large (from atom to object). This is the paradigm of nanotechnology.

Basically, at present, nanotechnologies are dominated by technological methods that have come to us from macrotechnologies. To create nanoparticles that belong to the class of 0-D objects. Modern nanotechnologies use the method of dispersion, i.e. grinding. In order to grind (disperse) any macroscopic object to nanoscale, conventional dispersion is not suitable. The smaller the particle size, the higher the activity of their surface; as a result, individual particles are combined into bulk conglomerates. Therefore, ultrafine dispersion requires the use of a certain type of medium in the form of surfactants that reduce surface tension forces, as well as stabilizers. Soap-like compositions that prevent re-fusion. Under certain conditions. When the surface energy at the boundary of a solid body is greatly reduced, the dispersion process can occur spontaneously, due to. For example, the thermal motion of particles. These methods can be used to obtain Me powders with particle sizes of tens of nm. Oxides of these metals with particle sizes of 1 nm. And also to produce dispersion of polymers, ceramic components, etc.

Grinding methods: ball mill, vibrating mill, attritors, jet mills.

1)

2) In addition to dispersion, a process is widely used that is a combination of two-limited paradigms. This process consists of the evaporation of a solid, followed by condensation under various conditions. For example, the condensation of a vapor of a substance heated to 5000-10000 ° C in a cooled inert gas with the rapid removal of the resulting powder from the condensation zone. In this way, powders with particle sizes of 3-5 nm can be obtained.

1 - Source of evaporating substance

2- Pumping out

3 - Powder

4 - Scraper

5 - Condensation drum

3) The third method is also related to traditional dispersion and is called atomization of a molten substance in a stream of cooled gas or liquid.

N 2 , Ar 2 can serve as the gaseous medium of the jet knocking down the droplet, and alcohols, water, acetone can serve as the liquid. In this way, particles with sizes of about 100 nm can be obtained.

All the described processes are very productive, but as a rule they do not provide ultradispersion of the powder, particle size stability and do not ensure the purity of the process. These are not the only known ways to form nanoparticles. 0-D nanoobjects, in addition to ultrafine powders, also include fullerenes, carbon 0-D nanoobjects.

Chapter 1- D nanoobjects.

Each of these nanoobjects finds its application in various branches of technology. For example, nanowires are proposed to be used as conductors in submicron and nanoelectronic nodes. Nanofibers are used as an element of nanostructured nanocomposite p/p. Organic macromolecules also find application in the creation of nanostructured materials.

In medicine, in the chemical industry.

For electronics, such 1-D nanoobjects as nanotubes have become very significant. By and large, all nanotubes are divided into 2 large classes:

1) Carbon nanotubes (CNTs).

2) non-carbon nanotubes.

In addition, all nanotubes differ in the number of layers: single-layer, two-layer, multilayer.

NON-CARBON NANOTUBES

All non-CNTs are divided into two systems:

1) Transition nanostructures containing carbon

2) Dichalcogenide nanotubes. Currently, MoS 2 ,WS 2 , WSe 2 , MoTe 2 , etc. are known from dichalcogenide tubes. Such nanotubes are ultrathin, ideally monatomic layers, materials rolled into a roll.

Some layered materials, due to the asymmetry of chemical bonds, quite freely roll up into such rolls on their own, and the only problem in the formation of such structures is to obtain a free, unconnected layer of an atomic-sized substance. Other materials are not prone to spontaneous folding, and therefore technological methods are currently being developed that allow the formation of nanotubes by force. There are 3 options for such processes:

1) Heteroepitaxial growth of thin layers of the material from which we want to form a nanotube, based on an already existing nanotube. Example GaN→ZnO

The main disadvantage of this method is that it is difficult to select a pair of materials for heteroepitaxial growth.

2) Single-walled nanotubes obtained by sequential reduction of the original nanowire by an electron beam. Example: Gold and platinum nanotubes. D Pt nanotubes - 0.48 nm.

3) It is based on the growth of a thin, strained heteroepitaxial structure, several monolayers thick, on a flat substrate, followed by the release of this heterostructure from the bond with the substrate and rolling into a tube, a scroll. 1ML is one monolayer.

The folding process occurs due to the action of interatomic forces in a strained heterofilm.

On In, a well-matched AlAs is grown by heteroepitaxy; then, an AsIn layer is grown on this structure by the GE method. It has larger crystal lattice parameters than AlAs, and therefore, when this layer grows, it seems to shrink. Then, again, a GaAs layer is grown on this layer by the GE method. But, unlike AsIn, this layer has a smaller crystal lattice parameter (smaller unit cell size) and, on the contrary, stretches it. As a result, when we start etching the AsAl layer, the released InAs c AsGa structure begins to roll into a tube due to forces that expand InAs and contract the GaAs layer.

Advantages of the method:

1) The diameter of the tubes varies widely and can be easily specified with a set of appropriate heterostructure materials.

2) The method makes it possible to use practically any materials (p/p, Me, dielectrics) and to roll all of them into nanotubes.

3) Good quality and relatively long tubes with uniform walls.

4) The method fits well with the technology of IC integrated circuits.

5) The physical properties of such nanotubes are determined by the materials of the initial heterostructure.

2- D NANOOBJECTS (THIN FILMS)

Used in engineering. Like covers. The creation of thin-film coatings makes it possible to significantly change the properties of the initial material without affecting the volume and without increasing the geometric dimensions. Thickness is not more than 1 micron. The most common coating purposes are:

1) Improvement of wear resistance, thermal and corrosion resistance of materials of various parts.

2) Creation of planar, single-layer. Multilayer and heterostructures for elements of micro0, nanoelectronics, optoelectronics, sensors, etc.

3) Changing the optical characteristics of the surface (chameleon glasses)

4) to create magnetic media in the elements of recording and storing information.

5) Creation of optical means of recording and storing information. CDs, DVDs.

6) Creation of absorbers, separators of gas mixtures, catalysts, chemically modified membranes, etc. There are two fundamentally different approaches to improving the service characteristics of a surface (i.e., to creating films on them):

1) Modification of surface layers by various types of processing (chemical, thermal, mechanical, radiation, or combinations thereof).

2) deposition of additional layers of foreign atoms.

All coating methods can be grouped into two groups:

1) Physical vapor deposition. PVD

2) Chemical vapor deposition. CVD

In both cases, the process is carried out in a vacuum chamber, in which a small process gas pressure is sometimes created (relatively chemically neutral gases - Ar, N 2, ethylene)

In physical vapor deposition (PVD) methods, there are basically two methods of delivering new material to the substrate.

1) Spraying due to thermal heating (heating can be carried out in a variety of ways: resistive, electron beam, induction, laser, etc.

2) Sputtering due to the kinetic energy Ek of accelerated ions of neutral gases, for example, Ar ions. The positive Ar ion bombards the cathode, the target of the sputtered material is on the cathode, and so on. there is a physical dispersion of this material.

The difference is only in the way the material is sprayed.

A variety of coatings are applied by physical vapor deposition methods, since These methods have a wide range of advantages:

1) A wide variety of materials. Which can be applied in this way (Me. Alloys, polymers, some chemical compounds)

2) The possibility of obtaining high-quality coatings in a very wide range of substrate temperatures.

3) The high purity of this process, which ensures good adhesion quality.

4) No significant change in the dimensions of the parts.

In chemical vapor deposition methods, solid products (film) on the substrate grow as a result of a chemical reaction involving atoms of the working atmosphere of the chamber. As energy sources for the occurrence of such a reaction, plasma of some kind of electric discharge, sometimes laser radiation, is used. This type of technological processes is more diverse than the previous one. It is used not only to create coatings, but to produce nanopowders, which are then removed from the surface of the substrate.

In this way, it is possible to obtain chemical compounds with carbon - carbides, with N - nitrides, oxides, etc.

The advantages of chemical vapor deposition are:

1) flexibility and great variety, which allows coatings to be deposited on substrates of different nature and shape (on fibers, powders, etc.)

2) The relative simplicity of the necessary technological equipment. Easy automation.

3) Large selection of chemical reactions and substances suitable for use

4) Adjustability and controllability of the coating structure, its thickness and grain size.

5) grains are elements of a polycrystalline structure, those crystals that make up polycrystals.

Epitaxial processes play an important role in the production of thin-film structures. Epitaxy is a technological process of oriented growth of a layer of material on the surface of the same or another material, i.e. substrate, which performs the function of creating an orienting effect. If the materials of the substrate and film are the same, then the process is called autoepitaxy, if the materials of the substrate and film are different, then this is heteroepitaxy. All epitaxial processes are divided into two classes:

1) Processes with a carrier medium (liquid-phase and gas-phase epitaxy).

2) Without carrier medium (vacuum epitaxy). Molecular beam or molecular beam epitaxy.

liquid phase epitaxy. Advantages and disadvantages.

Liquid phase epitaxy is mainly used to obtain multilayer semiconductor compounds such as GaAs, CdSnP2; is also the main way to obtain single-crystal silicon. The process is carried out in an atmosphere of nitrogen and hydrogen (to restore oxide films on the surface of the substrates and melt) or in vacuum (preliminarily restore oxide films). The melt is applied to the surface of the substrate, partially dissolving it and removing impurities and defects.

Gas phase epitaxy. Advantages and disadvantages.

Vapor-phase epitaxy - obtaining epitaxial layers of semiconductors by deposition from the vapor-gas phase. It is most commonly used in the technology of silicon, germanium and gallium arsenide semiconductor devices and ICs. The process is carried out at atmospheric or reduced pressure in special vertical or horizontal type reactors. The reaction takes place on the surface of substrates (semiconductor wafers) heated to 750 - 1200 °C

Molecular beam (beam) epitaxy. Advantages and disadvantages.

Molecular beam epitaxy (MBE) or molecular beam epitaxy (MBE) is epitaxial growth under ultrahigh vacuum conditions. Allows growing heterostructures of a given thickness with monatomically smooth heterointerfaces and with a given doping profile. The epitaxy process requires special well-cleaned substrates with an atomically smooth surface.

Oriented extension. A crystalline body is visible to the naked eye - a flat, solid surface.

Through the microscope: atomic and chemical bonds

Any atom located directly on the surface has a dangling, incomplete chemical bond. And this connection is the Ep minimum.

The orienting effect of substrate atoms on the location of a free atom when it is deposited on a surface.

CARBON NANOMATERIALS

The American architect Fuller introduced a new design element to architecture.

In 1985 Carbon particles were found connected in a similar design. These substances were called fullerenes. C-60 fullerene (60 C atoms), C-70 fullerene (70 C atoms), possible C-1000000 fullerene.

Carbon atoms can form a highly symmetrical C-60 molecule, consisting of 60 atoms and located in a sphere with a diameter of 1 nm. At the same time, in accordance with Leonhard Euler's theorem, carbon atoms form 12 regular pentagons and 20 regular hexagons.

C-60 molecules, in turn, can form a crystal called fullerite, which has a face-centered cubic lattice (fcc) and fairly weak intermolecular bonds. Taking into account that fullerenes are much larger than atoms, the lattice turns out to be loosely packed, i.e. has octahedral cavities in the volume, and tetrahedral cavities in which foreign atoms can be located. If the octahedral cavities are filled with alkali Me (K, Rb, Cs) ions, then at temperatures below room temperature, fullerene turns into a fundamentally new polymer material, which is very convenient for the formation of polymer blanks in near-Earth space (for example, bubbles). If the tetrahedral cavities are filled with other ions, then a new superconducting material with a critical t=40÷20 K is formed. Due to the ability to adsorb various substances, fullerites serve as the basis for creating new unique materials. For example, C 60 C 2 H 4 has strong ferromagnetic properties. Currently, more than 10,000 species are known and used. Molecules with a gigantic number of atoms can be obtained from carbon. For example, C 1000000 . These are, most often, single-walled or multi-walled CNTs (elongated nanotubes). At the same time, the diameter of such a nanotube is ≈1 nm, and the length is units, tens of mm is the maximum length. The ends of such a tube are closed with 6 regular pentagons. It is currently the most durable material. Graphene is a regular hexagon, has a flat structure, but it can also be wavy if the graphene sheet is created not from alternating regular hexagons, but from a combination of 5-7 gons.

SYNTHESIS OF CARBON NANOMATERIALS.

The first fullerenes were isolated from condensed graphite vapors obtained by laser evaporation of solid graphite samples. In 1990 A number of scientists (Kretcher, Hoffman) have developed a method for obtaining fullerenes in the amount of several grams. The method consisted in burning graphite rods - electrodes in an electric arc in an He atmosphere at low pressures. The selection of optimal process parameters made it possible to optimize the yield of suitable fullerenes, which, from the initial mass of the rod, is 3–5% of the mass of the anode, which partly explains the high cost of fullerene. The Japanese were interested in this. Mitsubishi has managed to establish commercial production of suitable fullerenes by burning hydrocarbons. But such fullerenes are not pure, they contain O 2 in their composition. Therefore, the only clean way to get it is by burning He in an atmosphere.

A relatively rapid increase in the total number of installations for the production of fullerenes and their purification led to a significant reduction in prices for them (first 1 gram - $ 10,000, and now - $ 10÷15). The high cost of fullerene (as well as other carbon n/m) is explained not only by a low yield, but also by a complex purification system. Standard cleaning scheme: when burned, something like soot is formed. It is mixed with a solvent (toluene), then this mixture is filtered, then distilled off in a centrifuge, so that the largest ones are isolated from the remaining small inclusions. Then evaporated. The remaining dark precipitate is a finely dispersed mixture of various fullerenes. This mixture should be divided into individual components. This is done by liquid chromatography, high resolution electron microscopy and by scanning probe microscopy.

Initially, CNTs were also produced by the method of electric arc or laser evaporation of graphite followed by condensation in an inert gas medium. This method turned out to be far from the best. Therefore, at the moment, the most practical method is chemical vapor deposition. To do this, take a carbon-containing compound, for example, acetylene, it is decomposed on the surface of a very heated Me catalyst. And on the surface of this catalyst, CNTs begin to grow in a dense bundle. This reaction is called catalytic pyrolysis of gaseous hydrocarbons. Most often it is realized in rotary tube furnaces. In this case, Fe, Co, Ni act as catalysts, the particles of which saturate pieces of zeolite. Zeolite is a natural mineral. Unlike electric arc, laser, and other types of high-temperature synthesis, catalytic pyrolysis allows the fabrication of carbon nanostructures on an industrial rather than laboratory scale, and although they are less pure and less homogeneous in composition, they can be used. Graphene is a particle of graphite. Graphene flakes are placed on an oxidized Si substrate, which makes it possible to study graphene as an independent material; for electrophysical measurements. An example, a chemical way to get graphene: crystalline graphite is exposed to HCl and H2SO4, which leads to oxidation at the edges, in these graphene sheets. The carboxyl group of graphene is converted to chlorides by treatment with thionyl chloride. Then, under the action of octadecylamine, in solutions of tetrahydrofurans, carbon tetrachloride and dichloroethane, transformation into graphene layers 0.54 nm thick occurs.

A method for producing graphene on silicon carbide substrates, wherein graphene is formed by thermal decomposition of silicon carbide on the surface of the substrate. Studies have shown that the graphite layer that precipitates in this case has a thickness greater than one atomic layer, but since an uncompensated charge is formed at the interface between silicon carbide SiC, due to the difference in the work functions of electrons, then only one atomic layer of graphite participates in the conductivity, that is, this layer, in fact, is graphene.

USE OF CARBON NANOMATERIALS

1) Fullerenes are used to modify optical media.

2) For the manufacture of fundamentally new composite materials, both with nanotube impurities and with fullerenes

3) For superhard coatings. Surfaces of tools, rubbing parts, etc. Achieve the properties of diamond in hardness.

4) For lubricants and additives.

5) For containers, the so-called. hydrogen fuel, which will later be used as chemical energy sources

6) For the manufacture of nanosensors that record physical and chemical types of impact. Sensitivity - 1 molecule of a foreign substance.

7) Probes for scanning microscopy.

8) For the manufacture of atomic manipulators

9) For the manufacture of nanomechanical data storage devices.

10) For the manufacture of nanowires, nanoresistors, nanotransistors, nanooptical elements.

11) For the manufacture of protective screens from e / m radiation and high temperatures. Stealth technology.

12) It is possible to make nanocontainers for medicines.

13) For the manufacture of large-sized plane-parallel displays of high definition and brightness.

OPERATING PRINCIPLE OF A SCANNING TUNNELING MICROSCOPE (STM)

If two separate atoms are brought together at a sufficient distance, then an exchange of electrons between these atoms is possible without additional acquisition of energy by these electrons. Therefore, if we take two bodies, bring them closer to a sufficient distance, then a tunnel electric current will flow between these bodies, because the process of electrons passing through a potential barrier without acquiring energy is called tunneling. For this to happen, two conditions must be met:

1) One of the bodies must have free electrons, and the other must have unfilled electronic levels, to which these electrons could pass.

2) Between the bodies it is required to apply a potential difference, and its value is less than during the breakdown of the air gap.

In the STM, one of these bodies is a probe.

When approaching the probe and the surface of the object at a distance of approximately 0.5 nm (when the wave functions of the atoms closest to each other begin to overlap) and when a potential difference of ≈0.1 ÷ 1 V is applied between the probe and the object, the so-called. tunnel current.

The beam diameter of this tunneling current is ≈0.4 nm, which provides a high resolution of the microscope along the object plane. The tunnel current will be 3 nA. It is important to note that when the distance L changes by 0.1 nm, the tunneling current changes by a factor of 10. This is what ensures the high resolution of the microscope at the height of the object. In fact, during the measurement process, the probe, moving over the surface of the object, maintains a constant height.

Fixing the position of the probe, its coordinates in the XYZ system allows you to track the surface profile and then convert it into the corresponding picture on the monitor screen.

Because the distance between the probe and the surface under study during the measurement process is no more than 0.3÷1 nm, then it can be argued that the measurement process, in fact, changes in vacuum. In air - 20 nm. In fact, the environment exerts an influence due to the molecules adsorbed on the surface.

TECHNICAL CAPABILITIES OF THE SCANNING TUNNELING MICROSCOPE (STM)

The main technical characteristics are:

1) Resolution along the normal to the object surface under study

2) Resolution in the XY plane, i.e. in the plane of the object surface

The high resolution of the STM along the normal to the surface of the object is about 0.01 nm. It is determined by the steep exponential dependence of the tunneling current on the distance between the object and the probe. In the XY plane, high resolution is provided by the diameter of the electron beam of the tunneling current, which, in turn, depends on the degree of sharpening of the probe tip. With repeated passage of the probe with a step of ≈0.02 nm, the resolution in the XY plane can reach 0.03 nm. The actual resolution of the STM depends on many factors, the main of which are: external vibrations, acoustic noise, and the quality of the probes. In addition to the resolution of the microscope, the most important characteristic is the so-called. useful magnification,

where dГ=200 µm (eye resolution), dМ is the maximum resolution of the microscope. dM =0.03 nm (for STM). That. once. For comparison: the best optical microscopes have times

Other important STM characteristics:

The maximum size of the scanning field is 1x1 µm.

The maximum movement of the probe along OZ (in the process of measurement) does not exceed 1 µm.

In principle, modern microscopes can provide a scanning field of up to several hundred, but the accuracy deteriorates. In addition to measuring the surface profile and creating its visual model, STM makes it possible to judge the type of electrical conductivity of the material (for p/p), to set the parameters of the valence band of the IG, the conduction band of the GB, and the energy characteristics of impurities (i.e., to determine the position of impurity levels). Determine the chemical type of bond between the atoms of the surface of the object; determine the chemical composition of the surface of an object or surface layer - the so-called. STM spectroscopy.

ATOMIC FORCE MICROSCOPE (SCANNING FORCE MICROSCOPE) AFM.

The difference from STM lies in the fact that the probes (cantilevers) interact with the surface under study not electrically, but by force.

The dependence of the strength of two atoms on the distance. The repulsive force increases in . It is fundamentally impossible to combine two atoms at one point in space.

The cantilever needle touches the surface of an object and is repelled by that surface as it approaches the interatomic interaction distance. The oscillations of the cantilever probe are converted into electrical signals in various ways (the simplest is the optical method). Optical way:

This signal contains altitude information. On which the cantilever landed at a particular measurement step. Information about movement in the XY plane is recorded from the movement mechanisms of this plane under study.

In addition to optical conversion methods, capacitive or tunnel sensors can be used, since between the object under study and the probe (in the e AFM microscopy mode), then AFM can examine not only conductive objects, but also dielectric ones. Requirements for the object - it must be smooth (so that there are no large differences in heights) and solid (gaseous and liquid objects do not make sense to explore).

The resolution of the AFM directly depends on the quality of the probe sharpening.

The main technical difficulties of this type of microscopy:

1) The complexity of manufacturing a probe sharpened to the size of one atom.

2) Providing mechanical. Including. Thermal and vibrational stability at a level better than 0.1 Å.

3) Creating a detector. Capable of registering such small movements.

4) Creation of a sweep system with a step in fractions of Å.

5) Ensuring smooth approach of the probe needle to the surface.

Compared to the SEM scanning electron microscope, AFM has a number of advantages:

1) AFM allows obtaining a true three-dimensional surface topography, SEM has a 2D image

2) A non-conductive surface viewed by AFM does not require a metallic layer.

3) SEMs require a vacuum for normal operation, while AFMs do not require vacuum.

4) AFM has the potential to provide higher resolution than SEM
The disadvantages of ASM are:

1) Small size of the scanning field (compared to SEM).

2) Strict requirements for the size of the vertical height differences of the scanned surface. We will see a file in SEM, but not in AFM.

3) Strict requirements for probe geometry. Which is very easy to damage.

4) Practical irremovability of distortions. Which introduces the thermal motion of the atoms of the surface under study. This shortcoming could be eliminated if the scanning rate exceeded the rate of thermal motion of molecules, i.e. at each moment in time the picture is different.

All these problems are somehow compensated by software processing of the measurement results, however, it should be remembered that what we see on the computer screen is not a real surface, but a model, and the degree of reliability of the model is in question.

At present, STM and AFM scanning probe microscopes are widely used in all fields of science (in physics, chemistry, biology, materials science).

Nanotechnological probe machines.

Initially, when the fundamental possibility of moving individual atoms with an STM probe was established, scientists experienced some euphoria - they already dreamed of assembling all kinds of objects not only in the nanoworld, but also in the macrocosm. Nevertheless, based on the achievements of STM microscopy, devices called nanotechnological probe machines have been created. If a greater potential difference is applied between the object and the probe than when measuring the parameters of the surface of the object, then any atom of the surface can be excited (teared off from the surface) due to the energy. This excited atom. As a rule, it sticks to the probe, and, accordingly, this probe can be transferred to a new place, and when the energy supplied to the probe decreases (with a decrease in the potential difference), it is again lowered to the surface. But at that time, the problem of fixing (forced) alien atoms on the surface of an object under conditions other than absolute zero or close to absolute zero was not solved.

Thanks to the studies carried out, we now know the excitation energies of atoms of various materials and the issue of supplying atomic gas to the STM probe operation zone has been solved. In fact, it is the presence of a device for supplying atomic gas to the working zone that distinguishes a probe nanotechnological machine from STM.

At present, the principles of controlling multi-probe machines have already been developed, which makes it possible to increase their productivity, and therefore increase the likelihood of a wider use of such a probe atom-by-atom assembly and, ultimately, to make assembly in the “bottom-up” direction cost-effective.

IN WHAT DIRECTIONS NANOTECHNOLOGIES DEVELOP.

1) The “bottom-up” direction is implemented, i.e. atom assembly.

2) Creation of new nanomaterials by macroscopic and physicochemical methods.

ACHIEVEMENTS OF NANOTECHNOLOGIES.

1) Nanometer surface control is in demand in the production of such things as contact lenses, the creation of nanoelectronic devices.

2) scanning probe microscopy is currently unmatched in accuracy. With its help, you can find and move individual atoms and create groups of atoms. However, such designs are not suitable for mass use.

The most promising material, from the point of view of nanotechnology, is carbon C, which has unique chemical properties:

1) Allows you to create molecules with an unlimited number of atoms.

2) It has an isomorphism of the crystal lattice, i.e. different types of crystal lattice.

Huge amounts of money are currently being invested in nanotechnology.

The term "nanoelectronics" is logically related to the term "microelectronics" and reflects the transition of modern semiconductor electronics from elements with a characteristic size in the micron and submicron region to elements with a size in the nanometer region. This process of technology development reflects Moore's empirical law, which states that the number of transistors on a chip doubles every one and a half to two years.

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