RU2436876C1 - Formation method of multi-layer nanocrystalline films with heterogeneous boundary line and formation device of multi-layer nanocrystalline films with heterogeneous boundary line - Google Patents

Abstract

FIELD: electricity. ^ SUBSTANCE: method consists in preparation of solution of mixture of metal salts, aerosol application of the above solution to the substrate surface in gas carrier flow, removal of solvent from the solution of mixture of metal salts and formation on surface of substrate of multi-layer nanocrystalline films of metals as a result of thermal decomposition of metal salts; at that, surface of substrate is pre-heated; aerosol fog is formed from solution of mixture of metal salts, which is transferred and deposited on the substrate surface of oxygen-containing carrier gas; carrier gas pressure is maintained higher than atmospheric pressure; heterogeneous boundary line is formed by applying to the formed nanocrystalline layer of nanocrystalline layer of the other chemical composition differing from the previous one. Actually, there proposed is new manufacturing technology of metal semiconductor and dielectric materials and instruments by using nanocrystalline films with high adhesion and various phase composition. ^ EFFECT: obtaining multi-layer alternating nanocrystalline films of various phase composition with possibility of performing the monitoring of thickness of films and dispersability of grains; increasing the capacity of obtaining such multi-layer alternating nanocrystalline films; reducing the time of their obtaining; reducing the labour intensity of the process, and simplifying the device implementing the proposed method. ^ 8 cl, 7 dwg, 19 ex, 2 tbl

Description

The invention relates to the field of materials science and can be used in the manufacturing technology of metallic, semiconductor and dielectric materials and devices, in particular, for applying multilayer nanocrystalline thin films of these materials in a chemical way.

Known methods of forming multilayer nanocrystalline films based on the production of metal oxide semiconductors of films using hydrolytic and pyrolytic reactions [1-3], the essence of each of which is as follows.

Based on hydrolytic reactions. Hydrolysis is one of the types of interaction of substances with water with the formation of various compounds. Many chemical compounds are prone to hydrolysis not only in aqueous solutions, but also when interacting with water vapor. This method is widely used to obtain metal oxide semiconductors. The starting materials are aqueous or alcoholic solutions of halides (usually chlorides) or organometallic compounds of the corresponding metals. Reactions of the type 2InCl ₃ + 3Н ₂ О → In ₂ O ₃ + 6HCl and SnCl ₄ + 2Н ₂ О → SnO ₂ + 4HCl proceed at temperatures of several hundred degrees either directly on the heated surface onto which the film is applied (spraying method), or in the space adjacent to this surface (reaction method in the gas phase).

The method for producing thin films from the gas phase is based on chemical reactions between volatile hydrolyzable compounds.

Hydrolysis in the vapor phase can be reversible and irreversible. The mechanism of hydrolysis of substances in a gaseous state depends on the chemical nature of the starting substance, its reactivity and hydrolysis conditions. In practice, the hydrolysis conditions of the film-forming compounds in the vapor state are selected so that the hydrolysis proceeds irreversibly. In this case, one of the final products of hydrolysis should be a substance that condenses from vapor in solid form on the surface of the processed products. Hydrolysis of chemical compounds in a gaseous state in most cases occurs at relatively low temperatures. Chlorides, alkoxy compounds of various elements [1], halogen-containing, organosilicon compounds and partially substituted alkoxy compounds with various alkyl and aryl organic radicals are easily hydrolyzed in the vapor phase. All of them can be deposited in the form of thin films of hydroxides.

The deposition of films from the vapor phase is carried out in various ways using a variety of equipment. The easiest way is to supply the vapor of film-forming substances or the vapor of their solutions in an inert solvent under a glass cover, where the parts to be coated with a film are placed. Under the cap, a certain elasticity of water vapor is created. In most cases, upon receipt of films of SiO ₂ , SnO ₂ , TiO _2, and others, pairs of individual volatile compounds are used. Using an inert carrier gas (nitrogen, argon), these vapors are transferred to the apparatus, where workpieces are placed on special supports heated to the required temperature. At the same time, water vapor is also supplied with the necessary constancy of the rate of their entry into the reaction zone.

The hydrolytic method for producing films of titanium, tin and antimony oxides from the vapors of the corresponding chlorides, and SiO ₂ films from vapors of Si (OCH ₃ ) ₄ can be implemented according to the following schemes:

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Hydrolysis of salts occurs at low temperatures, and the deposition of the corresponding oxides is carried out on surfaces heated to temperatures acceptable for various glasses and crystals. The resulting films are transparent, uniform, amorphous, firmly fixed on the surface of the glass and can be obtained with a thickness of several tens of angstroms to 1.5-2.0 μm on the surface of products of various profiles and configurations.

SnO ₂ films are often prepared from SnCl ₄ . Its decomposition easily proceeds at room temperature, and therefore can be used for the formation of films on products from glasses, crystals, ceramics and other materials.

The process of formation of SnO ₂ films can be represented as follows. When air containing SnCl ₄ vapors is mixed with water vapor, ortho-tin acid is formed in a finely divided state:

SnCl ₄ + 2H ₂ O = Sn (OH) ₄ + 4HCl.

Ortho-tin acid, adsorbed onto the surface of the substrate, dehydrates, forming a uniform transparent layer of tin dioxide:

Sn (OH) ₄ = SnO ₂ + 2H ₂ O.

The thickness of the resulting film can be controlled by the vapor feed rate and hydrolysis conditions (temperature, residence time of the substrates in the vapor and the concentration of the film-forming substance). As the surface temperature of the product increases, the adhesion and strength of the films increase. The most uniform in thickness and having good adhesion to the substrate films are formed when the substrate is heated to 200-300 ° C.

Similarly, films of the chlorides of the corresponding metals can be obtained: SiO ₂ , TiO ₂ , Fe ₂ O ₃ , In ₂ O ₃ , Sb ₂ O ₃ , CdO, CuO, NiO, etc. [1-3].

The disadvantages of the methods of forming films using hydrolytic reactions are the heterogeneity of the composition of the films due to the hydrolysis of chemical compounds (for example, from an alcohol solution of SnCl ₄ · 5H ₂ O) at relatively low temperatures in the gaseous state, as a result of which the composition of the films may differ from stoichiometric, the presence of intermediate compounds associated with insufficiently complete oxidation of the solution products (for example, the presence of inclusions in films such as Sn (OH) Cl, etc.). Insufficient adhesion between the film and the substrate, due to the impossibility of establishing thermodynamic equilibrium between them due to the relatively low temperatures of chemical reactions.

Based on pyrolytic reactions. Pyrolysis - decomposition or other transformations of a substance when heated. The method of producing films from the gas phase during the pyrolysis of some compounds is becoming much more widespread in optical instrumentation, radio engineering, and in the technology for manufacturing semiconductor devices [1-3].

Thermal decomposition of organic compounds most often begins with the formation of free radicals. Such radicals as, for example, CH ₃ -, C ₂ H ₅ -, having greater activity than the original molecules, react with each other and with the undissociated molecule. In this case, a free radical can again form, which, in turn, reacts with an undissociated molecule and so on. A chain of transformations arises leading to the complete decomposition of the starting material.

By pyrolysis, films of oxides of various elements can be obtained. Particularly thermostable and chemically stable oxides of elements of groups III and IV of the periodic system of elements. They are used to protect semiconductor products and easily destroyed by water vapor optical parts made of glass and crystals. The starting materials for the formation of such films can be alkoxy compounds of titanium, tin, aluminum and other elements, chlorosilanes and silicon chlorides, titanium, aluminum, acetooxy compounds of silicon, zirconium, etc. In addition, silicon, germanium, and other hydrides are also used.

The most widespread pyrolysis for the deposition of protective films from oxides of silicon and aluminum. The decomposition reactions of alkoxysilanes, especially tetraethoxysilane, have been well studied.

The decomposition reaction of tetraethoxysilane can be represented by the following scheme:

2Si (OC ₂ H ₅ ) ₄ = Si ₂ O (OC ₂ H ₅ ) ₆ + 2C ₂ H ₄ + H ₂ O,

Final hydrolysis leads to the formation of SiO ₂ .

The thermal decomposition of alkoxy compounds often also produces amorphous Al ₂ O ₃ films. Depending on the nature of the alkoxy group, this reaction proceeds at various temperatures. For example, aluminum propylate decomposes at 420 ° C [1], aluminum ethylate at 550-800 ° C, and aluminum triisobutylate at 250-500 ° C. Upon thermal decomposition of aluminum alkoxy compounds, a mixture of gradually decomposing compounds is obtained: Al (OR) ₃ → Al (OR) ₂ OH + Al (OR) (OH) ₂ + Al (OH) ₃ , as a result of complete decomposition of which amorphous compounds form on the surface of the workpieces Al ₂ O ₃ films. The latter are glassy, homogeneous, chemically inert, free from impurities and are characterized by high thermal stability.

The production of thin transparent films by thermal decomposition is of particular interest in the technique of manufacturing conductive coatings based on tin oxides according to the following scheme:

SnCl ₂ + H ₂ O → SnO + 2HCl,

2SnO + O ₂ → 2SnO ₂ ,

2SnO → Sn + SnO ₂ .

The main amount of reagents interacts before contact with the substrate and does not settle on it. The formation of the film occurs only due to the part that reacts directly at the surface of the substrate.

The disadvantages of the known methods of forming films using pyrolytic reactions is the heterogeneity of the films in composition due to the use of an alcoholic solution of metal chloride heated to a temperature of 450-500 ° C (for example, SnCl ₄ · 5H ₂ O), which does not allow the delivery of vaporous particles to the substrate surface solution of the same size and composition due to the pressure difference of the individual components of steam vapor (for example, an alcohol, H ₂ O, SnCl _4, Cl _2, O _2, etc.) above the liquid surface and does not allow in this case the nano ristallicheskie film with stable grain size. In addition, the spraying methods used in most cases do not allow sufficient control over the size of the sprayed vapor particles, and this also leads to the formation of inhomogeneous films.

A known method of forming multilayer nanocrystalline films based on the production of nanostructured films of titanium dioxide [4], which can be used in biotechnology for immobilization of enzymes on mesoporous nanostructured films of titanium dioxide in order to obtain photobiocatalysts.

This method [4] includes applying to a solid substrate a water-containing composition based on titanium dioxide containing a stabilizer and a pore-forming polymer, followed by drying and calcination. To prepare an aqueous composition, a titanium dioxide nanocrystal powder with an average particle size of 6 to 25 nm and a specific surface area of 50-300 m ² / g, which is mixed with a stabilizer and subjected to ultrasonic disaggregation, is used. Then add a pore-forming polymer in an amount of 10-30% by weight of titanium dioxide and an aqueous solution of a surfactant (surfactant) to a mass ratio of TiO ₂ : H ₂ O = 1: 1 ÷ 10. The resulting paste is homogenized by ultrasound, applied to a substrate, dried at room temperature and calcined in the presence of air or oxygen at a temperature of 400-600 ° C. In the method of immobilizing an enzyme, an enzyme is adsorbed on the surface of the obtained nanocrystalline mesoporous titanium dioxide film in a buffer solution at pH <8. The invention allows to provide a thickness of the obtained films of at least 2 μm for immobilization of a sufficient amount of the enzyme on them and for the effective course of photobiocatalytic processes (in t / e efficiency).

The disadvantage of this method [4] is the low adhesive strength, the inability to influence over a wide range of dispersion, orientation, etc. This is due to the fact that the invention used a precursor of the obtained films in the form of an aqueous composition based on titanium dioxide containing a stabilizer and a pore-forming polymer. After applying the precursor to the surface of the substrate, drying and calcination are carried out. Since the main material of the TiO ₂ film in the precursor is already in a solid state formed as a particle, it is impossible to influence its dispersion, adhesive strength, orientation, etc., over a wide range. With this method of deposition, no active chemical reactions occur at the precursor-substrate interface, which also negatively affects the quality of the films.

There is another method [5] for producing nanoparticles and manufacturing materials and devices containing nanoparticles that can be used to obtain metal-containing materials (such as, for example, thin-film composite materials, metal polymers designed to develop functional elements in electronics, electrical engineering, and optics and to develop efficient catalytic systems). The known method [5] for the preparation of nanoparticles involves the processes of their synthesis as a result of chemical transformations of the starting precursor reagents under the influence of chemical effects or chemical and physical effects, or their combinations in a monomolecular layer on the surface of the liquid phase. A method of manufacturing materials containing nanoparticles, is the introduction of the above particles into the composition of the material.

The disadvantage of this method is the low adhesion to the substrate due to the low temperature of the formation of films, precluding obtaining high adhesive strength.

A known method of forming multilayer nanocrystalline films based on the synthesis of nanocrystalline oxides and hydroxides, which relates to methods for producing nanocrystalline materials by chemical means and which involves spraying a reagent solution into a previous solution to form a precipitate of nanocrystalline oxide or hydroxide [6]. This method is the closest to the claimed invention and is selected as a prototype.

The known method involves spraying a reagent solution into a precursor solution to form a precipitate of nanocrystalline oxide or hydroxide. The precipitate is then subjected to heat treatment, followed by sonication or sonication, followed by heat treatment. This method produces nanocrystalline doped and undoped nickel hydroxide, manganese dioxide and zirconium oxide stabilized with yttrium, etc. In this case, unusual morphological superstructures can be obtained, including clearly distinguishable cylinders or nanorods, as well as new structures for nickel hydroxide and manganese dioxide, including assemblies of nanostructured fibers, agglomerates of nanostructured particles and assemblies of nanostructured fibers and nanostructured particles. These new structures have high flow rates and a high density of active sites, which makes them particularly suitable for the manufacture of catalysts.

The disadvantage of the prototype [6] is the multi-stage process, which leads to the duration and cost of the process of forming multilayer nanocrystalline films due to the fact that the first get a precipitate of nanocrystalline oxide or hydroxide, and only then subjected to thermal, ultrasonic and other treatments. In addition, it is difficult to obtain alternating nanocrystalline films of different phase composition with a controlled film thickness and a controlled grain dispersion by the indicated method [6]; it is difficult to obtain films with high adhesion due to the fact that the formation of oxides and subsequent heat treatment are separated in time (i.e., they are not carried out at the same time).

A device for implementing the method of forming multilayer nanocrystalline films [7], which is closest to the claimed invention, is known. The known device consists of a main quartz ampoule and two additional ampoules, with the help of which alloy films are grown from the gas phase using two additional sources of steam, one with its own component, the other with a dopant.

The disadvantages of the known device are the design complexity that does not allow its repeated use, labor intensity, low productivity, high cost of component materials (tubes made of optical quartz, lead, selenium and high purity lead selenide, etc.), the presence of high vacuum, the use of a heater for simultaneous heating both sources of steam (despite the fact that at a given time only one source is needed in the heater), difficulties associated with controlling the particle size of the steam, etc.

The claimed group of inventions (a method of forming multilayer nanocrystalline films and a device for its implementation) is free from these disadvantages.

The technical result of the claimed invention is the possibility of obtaining multilayer periodically alternating nanocrystalline films of different phase composition, controlled film thickness, controlled grain dispersion, as well as an increase in productivity and a significant simplification of the device for implementing the claimed method.

The specified technical result is achieved by the fact that in the method of forming multilayer nanocrystalline films with a heterogeneous interface, which consists in preparing a solution of a mixture of metal salts, aerosol application of the solution on the surface of a substrate in a carrier gas stream, removing solvent from a solution of a mixture of metal salts and forming on the surface substrates of multilayer nanocrystalline metal films as a result of thermal decomposition of metal salts, in accordance with the claimed invention The surface of the substrate is preheated, an aerosol fog is formed from the solution of the mixture of metal salts, which is transferred and deposited onto the surface of the substrate with a stream of oxygen-containing carrier gas, the pressure of the carrier gas is maintained above atmospheric, a heterogeneous interface is formed by applying another chemical layer to the formed nanocrystalline layer of the nanocrystalline layer composition different from the previous one.

In addition, the specified technical result is achieved by the fact that the substrate is preheated to a temperature in the range of 300-700 ° C.

In addition, this technical result is achieved by the fact that aerosol fog is formed using an ultrasonic generator.

In addition, this technical result is achieved in that the pressure of the carrier gas is maintained above atmospheric by no more than 0.3 atmospheres.

In addition, the specified technical result is achieved in that each nanocrystalline layer is formed from a solution of a mixture of metal salts containing the main component and the additive.

In addition, the specified technical result is achieved by the fact that tin dichloride with a percentage of from 95 to 100% in a mixture of metal salts is used as the main component.

In addition, this technical result is achieved by the fact that the additives use chlorides of other metals (antimony, copper, cadmium, indium, platinum, palladium, gold, silver, aluminum, zinc, nickel, erbium, etc.) with a percentage of not more than 5% in relation to the main component.

The specified technical result is also achieved by implementing the claimed method for forming multilayer nanocrystalline films with a heterogeneous interface, including a quartz reactor with substrates, a heater for heating substrates, two cuvettes isolated from each other for solutions of mixtures of metal salts, in which, in accordance with the invention, each of the two cuvettes isolated from each other is equipped with an ultrasonic generator, a compressor with a magnetic valve for p gulirovki overpressure in the reactor is connected to the substrate through the motor shaft, the output device is provided with a residual gas neutralizer, and a quartz reactor is designed as a pipe, on both sides of which metal sleeves are placed.

The essence of the claimed method is as follows.

The formation of nanocrystalline films with a heterogeneous interface was carried out by creating mixtures of metal salts in two sources using ultrasonic emitters of an aerosol fog from aqueous-alcohol solutions, applying these solutions on the surface of a heated substrate in a carrier gas stream, thermally decomposing metal salts and alternating the formation of nanocrystalline metal films on the surface of a heated substrate as a result of thermal decomposition of metal salts. A typical synthesis procedure includes three successive stages: (1) preparation of an aqueous initial solution of a mixture of metal salts, (2) reductive decomposition of the initial solution on the surface of the substrate to obtain a colloidal suspension of the desired phase of the final product, and (3) final formation of the film on the surface of the substrate by heat treatment .

The first stage is the preparation of an aqueous initial solution of a mixture of metal salts consists in the preparation of solutions of different composition. The following is an incomplete list of solutions (in parts by weight) used in the preparation of semiconductor nanostructured layers based on SnO ₂ :

1) 10 · (H ₂ O) + 5 · (SnCl ₂ · 2H ₂ O);

2) 10 · (H ₂ O) + 5 · (SnCl ₂ · 2H ₂ O) + 0.1 · (SbCl ₃ · 3H ₂ O);

3) 10 · (H ₂ O) + 5 · (SnCl ₂ · 2H ₂ O) + (0.1-0.7) · SbCl ₃ · NH ₄ F;

4) 10 · C ₂ H ₅ OH + 5 · (SnCl ₄ · 5H ₂ O) + 0.1 · (SbCl ₃ · 3H ₂ O);

5) 10 · C ₂ H ₅ OH + 5 · (SnCl ₄ · 5H ₂ O) + (0.1-0.2) · NH ₄ F;

6) 10 · C ₂ H ₅ OH + 5 · (SnCl ₂ · 2H ₂ O) + (0.1-0.2) · NH ₄ F;

7) 10 · (H ₂ O) + 5 · (SnCl ₂ · 2H ₂ O) + (0.1-0.7) · InCl ₃ ;

8) 10 · (H ₂ O) + 5 · (SnCl ₂ · 2H ₂ O) + (0.1-0.7) · ZnCl ₂ ;

9) 10 · (H ₂ O) + 5 · (SnCl ₂ · 2H ₂ O) + (0.1-0.7) · CuCl ₂ ;

10) 10 · (H ₂ O) + 5 · (SnCl ₂ · 2H ₂ O) + (0.1-0.3) · ErCl ₃ .

In accordance with the tasks to be solved, either one or a pair of films suitable for producing films in a device for the formation of nanocrystalline structures were selected from this list of solutions.

The second stage — the reductive decomposition of the initial solution on the surface of the substrate to obtain a colloidal suspension of the desired phase of the final product — consists of alternating the creation of mixtures of metal salts in two sources with the aid of ultrasonic emitters of aerosol fog from water-alcohol solutions and alternating aerosol deposition of the corresponding solutions on the surface of the heated substrate in the flow of carrier gas, and the final formation of a film suspension of the desired phase of the final product.

The third stage - the final formation of the film on the substrate surface by heat treatment consists in the alternate formation of all planned layers of different compositions, sufficient thermal exposure time at annealing temperatures, cooling the heater to room temperature and removing the formed multilayer film structure deposited on the substrate to solve the following problems.

The claimed method of forming multilayer nanocrystalline films is implemented using the device for forming multilayer nanocrystalline films, which is presented in Fig.1 and consists of a quartz tube 1, the inner working part of which is sealed from the outer space by two metal bushings 2; two ultrasonic steam sources 3, which in the inner middle region of the quartz tube alternately deliver ultrafine particles of vapor of two different compositions (solutions A and B) using carrier gas (dry air, hydrogen, argon, etc.), pumped by compressor 4 through the bottom sleeve; rod 5, rotating by means of an electric motor 6, introduced into the middle region of the quartz tube through the upper sleeve, and rotating the holder of substrates 7 with substrates 8, in which the required temperature is reached by heater 9; pipeline 10, providing input, transportation and withdrawal of reaction products through the entire device and then through the upper sleeve into the atmosphere through the catalyst 11, the speed of vapor movement through the pipeline is carried out using an electromagnetic valve 12.

The implementation of the claimed invention. Materials with a small-scale microstructure show amazing and attractive properties in terms of technology. In the works devoted to the production of metals and their alloys by rapid cooling of the composite materials of some glasses, where grain sizes of the order of several micrometers (microns) are reached, a wide range of manifestation of unusual properties is shown. Recently, however, studies have focused on reducing grain size from the micrometer interval to the nanometer interval.

A characteristic feature of such nanostructured materials is a large fraction of atoms (up to 50%) located at the boundaries of a grain or particle. Figure 2, where white circles indicate the boundary atoms of the grain, and dark circles indicate the internal atoms, schematically illustrates this phenomenon. A large fraction of atoms located on the boundary surfaces is important for creating a high density of potential centers for catalytic and electrochemical reactions.

Nanostructured materials, which relate to materials having a grain size of 1 to 100 nanometers (1 nm = 10 angstroms (Å)), have significantly different and in many cases improved chemical and physical properties compared to their equivalents of the same chemical composition, but with micron-sized grains.

Materials with a high specific surface area of nanoscale sizes are of particular interest for applications where chemical reactions caused by active centers play a decisive role. When using a catalyst, a large contact surface is important for oxidation and reduction by the environment, and therefore, reducing the catalytic material to a nanoscale clearly gives a noticeable advantage. The scope of the catalysts can also be associated with the cleaning of the environment from various types of pollution, with the neutralization of nuclear waste, water purification, purification from microparticles and air filtration, as well as catalysis for synthetic purposes, such as molecular sieves, oil refining and others. However, despite the great interest in the development of nanostructured materials, the use of modern nanostructured materials as a catalyst is the tendency of particles to form agglomerates in which the pore space between particles becomes comparable to the particle size, that is, where the pore space between particles has nanoscale sizes . Such small pore sizes limit the rate of active substances in and through the agglomerates.

Another area of use of nanostructured materials is rechargeable batteries and fuel cells, where the high specific surface of nanostructured materials increases the speed of interaction of the active material with the environment. For example, for rechargeable batteries with a high energy density, the need to withstand high current pulses under conditions of charging and discharging requires maximum contact between the electrode and the electrolyte in order to achieve a high transfer density of ions and electrons.

Active nanostructured materials with their high density of adjustable surface defects meet these requirements, thereby providing a way to optimize the high energy consumption of batteries.

The claimed method was tested on a laboratory installation of St. Petersburg State University, the test results of which are given in the form of specific results.

Examples of specific implementations of the claimed method. The process of forming layers based on tin dioxide was carried out in a laboratory setup, a diagram of which is shown in Fig.1. The substrates were pre-fixed on a substrate holder and heated to a temperature in the range of 300-700 ° C. Water-alcohol solutions based on tin chloride with precursors of different compositions were placed in the nodes of ultrasonic evaporators with solutions A and B, in cans with a capacity of 2-10 ml, ending with a drain tube.

The preparation of thin films of tin dioxide from tin dichloride in a device for the formation of nanocrystalline films as a result of thermal decomposition in an oxygen atmosphere can be represented as follows: 1) When SnCl ₂ · 2H ₂ O is dissolved in water, the solution becomes slightly cloudy due to the formation of white tin chloride. SnCl ₂ + H ₂ O → Sn (OH) Cl + HCl; 2) In the future, under the influence of temperature in the reaction chamber, divalent tin oxychloride decomposes, and upon transition to a gaseous state we have molecules of tin monoxide and hydrochloric acid Sn (OH) Cl → SnO + HCl; 3) In the future, in the atmosphere of oxygen and under the influence of temperature, tin dioxide is formed on the working substrate 2SnO + O ₂ → 2SnO ₂ and 2SnO → Sn + SnO ₂ ; 4) In this case, sulfuric acid vapors and other residual gases are removed from the working chamber through the converter to the outside.

Compressed air was supplied from the compressor to ultrasonic evaporators for supplying vapors to the working surface of the substrates, which entrained the pairs of corresponding precursors formed by ultrasonic generators in the reaction zone to the surface of the substrates. Air flow control, and accordingly the rate of vapor movement through the pipeline, was carried out using an electromagnetic valve. The time of the deposition process of the SnO ₂ -based layer varied from 2 to 10 minutes.

The necessary temperature values in the area of the substrates were maintained using a heater. The rotation of the substrates, in order to uniformly apply the films, was provided by a rod using an electric motor. With the successive deposition of several alternating layers on the surface of the substrates, the time and sequence of inclusions of ultrasonic evaporators with solutions A and B changed accordingly.

The thickness of the sprayed layers (d) was estimated by the method of reflective ellipsometry [8] or transmission electron microscopy [9], and the refractive index (n), according to the method described in [8].

The electrical resistance of the obtained layers, depending on the dopant, the layer thickness, and technological conditions of production, ranged from tens of Ohm · cm to hundreds of kOhm · cm and was determined by the method described in [10].

There are no fundamental restrictions on the choice of a precursor, and, accordingly, the composition of the films. It is possible to apply both single-component and binary compounds, as well as triple and more complex compounds. The main requirement, which must be met in this case, is that water-alcohol solutions can be prepared from the corresponding metal chlorides for subsequent film deposition from them.

Figure 3 presents the x-ray spectrum of the diffraction pattern of a semiconductor film of tin dioxide, formed by the proposed method from a solution of the composition (in parts by weight) 10 · (SnCl ₄ · N ₂ O) + 10 · C ₂ H ₅ OH, on a polycrystalline ceramic substrate 22-XC, captured on an X-ray machine DRON-2 (Cu-K _α - radiation).

In this diffractogram, only a set of basic reflections is observed, related to the crystalline phase of SnO ₂ (cassiterite), which was decrypted using the American Society for Testing and Materials (ASTM) card file, in this card file SnO ₂ is numbered No. 21-1250. In this case, phases other than the SnO ₂ phase were not detected.

The crystallographic characteristics of the SnO ₂ phase presented in the card index (ASTM): symmetry group-P4 / mnm (No. 136); α ₀ = 0.4738 nm; with ₀ = 0.3188 nm.

Figure 4 shows the topographic ACM image of a fragment of the surface of the SnO ₂ film obtained from a solution of 10 · (SnCl ₄ · Н ₂ О) + 10 · С ₂ Н ₅ ОН. It can be seen that the size of nano formations on the film surface is, on average, less than 50 nm, with a change in surface relief along the height of ~ 80 nm.

Figure 5 presents an image of a surface fragment of a SnO ₂ film doped with In ₂ O _{3 in an} amount of 2% obtained using a HITACHI S-3500N scanning electron microscope (SEM) equipped with a secondary electron detector and a Robinson back-scattered electron detector with the ability to enlarge the image from 15 to 30,000 times, accelerating voltage from 0.3 to 30 kV. The film was obtained from a solution of 9.8 · (SnCl ₄ · Н ₂ О) + 10 · C ₂ H ₅ OH + 0.2 · (InCl ₃ ) Images were obtained using a secondary electron detector at an accelerating voltage of 5 kV and magnification of 20,000 and 20,000 krat. It can be seen that the surface of the films consists of many whiskers having an arbitrary orientation of nanometer sizes in the range of 100-200 nm. Microscopic analysis of one-dimensional crystals made it possible to detect hemispherical formations (globules) at the vertices of all observed filaments, which are the result of solidified liquid droplets and evidence that the growth was carried out by the vapor-liquid-crystal (FLC) mechanism.

Figure 6 shows the image of the microstructure of the transverse cleavage film-substrate (film - SnO ₂ , the substrate is ceramic XC-22) in the reflected electrons. The SnO ₂ film thickness in this case is ~ 180 nm.

Figure 7 shows an electron microscopic image of a multilayer structure of 10 alternating layers of SnO ₂ (5 layers) and 9,8SnO ₂ + 0,2Sb ₂ O ₃ (5 layers), prepared according to the claimed method using the inventive device from solutions of tin tetrachloride and tin tetrachloride with antimony chloride of the compositions 10SnCl ₄ · 10H ₂ O + 10C ₂ H ₅ OH and 9.8SnCl ₄ · 9.8H ₂ O + 10C ₂ H ₅ OH + 0.2SbCl ₃ · N ₂ O. As can be seen from FIG. .7 distinguishable are both nanolayers of different compositions and their heterointerfaces.

Example 1. The process of forming films of tin dioxide (SnO ₂ ) was carried out in a laboratory setting (Figure 1). Substrates in the form of plates made of XC-22 ceramics in the amount of 3 pieces, with a thickness of 3 mm and an area of 0.5 cm ² each, were pre-fixed on a substrate holder and heated to a temperature of 300 ° C. An aqueous-alcoholic solution of tin tetrachloride of the composition 10SnCl ₄ · 10H ₂ O + 10C ₂ H ₅ OH in an amount of 3 ml was placed in one of the nodes of ultrasonic evaporators.

Compressed air was supplied to the ultrasonic evaporator containing the tin tetrachloride solution from the compressor, which entrained the solution pairs formed by the ultrasonic generator in the reaction zone to the surface of the heated substrates. The air pressure inside the quartz tube was 0.1 atmospheres higher than atmospheric. The duration of the deposition of SnO ₂ films was 2 min.

Example 2. All technological conditions for producing films coincide with those described in example 1, with the exception of the temperature of the substrates, which was 500 ° C.

Example 3. All technological conditions for the production of films coincide with those described in example 1, except for the temperature of the substrates, which was 700 ° C.

Example 4. All technological conditions for producing films coincide with those described in example 1, with the exception of the air pressure inside the quartz tube, which was 0.2 atmospheres higher than atmospheric.

Example 5. All technological conditions for producing films coincide with those described in example 2, with the exception of the air pressure inside the quartz tube, which was 0.2 atmospheres above atmospheric.

Example 6. All technological conditions for producing films coincide with those described in example 3, with the exception of the air pressure inside the quartz tube, which was 0.2 atmospheres above atmospheric.

Example 7. All technological conditions for producing films coincide with those described in example 1, with the exception of the air pressure inside the quartz tube, which was 0.3 atmospheres above atmospheric pressure.

Example 8. All technological conditions for producing films coincide with those described in example 2, with the exception of the air pressure inside the quartz pipe, which was 0.3 atmospheres above atmospheric pressure.

Example 9. All technological conditions for producing films coincide with those described in example 3, with the exception of the air pressure inside the quartz tube, which was 0.3 atmospheres above atmospheric pressure.

Table 1 shows the technological parameters and some properties for single-layer films grown from an aqueous-alcoholic solution of tin tetrachloride of the composition 10SnCl ₄ · 10H ₂ O + 10C ₂ H ₅ OH in an amount of 3 ml for 2 min.

Example 10. The process of forming films of tin dioxide (SnO ₂ ) doped with antimony oxide (Sb ₂ O ₃ ) was carried out in a laboratory setup (Figure 1). Substrates in the form of plates made of XC-22 ceramics in an amount of 3 pieces, with a thickness of 3 mm and an area of 0.5 cm ² each, were pre-fixed to the substrate holder and heated to a temperature of 300 ° C. A water-alcohol solution of tin tetrachloride and antimony chloride of the composition 9.8SnCl ₄ · 9.8H ₂ O + 10C ₂ H ₅ OH + 0.2SbCl ₃ · N ₂ O in an amount of 3 ml was placed in one of the nodes of ultrasonic evaporators.

Compressed air was supplied from the compressor to an ultrasonic evaporator containing a solution of tin tetrachloride and antimony chloride, which entrained the solution vapors formed by the ultrasonic generator in the reaction zone to the surface of the heated substrates. The air pressure inside the quartz tube was 0.1 atmospheres higher than atmospheric. The duration of the deposition of SnO ₂ films was 2 min.

Example 11. All technological conditions for producing films coincide with those described in example 8, with the exception of the temperature of the substrates, which was 500 ° C.

Example 12. All technological conditions for the production of films coincide with those described in example 8, except for the temperature of the substrates, which was 700 ° C.

Example 13. All technological conditions for producing films coincide with those described for example 1, with the exception of the air pressure inside the quartz tube, which was 0.2 atmospheres above atmospheric.

Example 14. All technological conditions for producing films coincide with those described in example 2, with the exception of the air pressure inside the quartz tube, which was 0.2 atmospheres above atmospheric.

Example 15. All technological conditions for producing films coincide with those described in example 3, with the exception of the air pressure inside the quartz tube, which was 0.2 atmospheres above atmospheric.

Example 16. All technological conditions for producing films coincide with those described in example 1, with the exception of the air pressure inside the quartz tube, which was 0.3 atmospheres above atmospheric pressure.

Example 17. All technological conditions for producing films coincide with those described in example 2, with the exception of the air pressure inside the quartz tube, which was 0.3 atmospheres above atmospheric pressure.

Example 18. All technological conditions for producing films coincide with those described in example 3, with the exception of the air pressure inside the quartz tube, which was 0.3 atmospheres above atmospheric pressure.

Table 2 shows the technological parameters and some properties for single-layer films grown from a water-alcohol solution of tin tetrachloride and antimony chloride of the composition 9.8SnCl ₄ · 9.8H ₂ O + 10C ₂ H ₅ OH + 0.2SbCl ₃ · H ₂ O10SnCl ₄ · 10H ₂ O + 10C ₂ H ₅ OH in an amount of 3 ml for 2 minutes

Example 19. The process of forming films consisting of 10 layers, alternating layers of tin dioxide (SnO ₂ ) and tin dioxide (SnO ₂ ) doped with antimony oxide (Sb ₂ O ₃ ), was carried out in a laboratory setup (Figure 1). Substrates in the form of plates made of ceramic XC-22 in an amount of 3 pieces, a thickness of 3 mm and an area of 0.5 cm ² each, were pre-fixed on a substrate holder and heated to a temperature of 500 ° C. Water-alcohol solutions of tin tetrachloride and tin tetrachloride with antimony chloride of the composition 10SnCl ₄ · 10H ₂ O + 10С ₂ Н ₅ ОН and 9.8SnCl ₄ · 9.8H ₂ O + 10C ₂ H ₅ OH + 0.2SbCl ₃ · Н ₂ O in an amount of 3 ml each, was placed in nodes A and B of ultrasonic evaporators.

Compressed air was supplied from the compressor to ultrasonic evaporators containing the corresponding solutions alternately, with an interval of 2 minutes, which entrained pairs of different solutions formed by ultrasonic generators in the reaction zone to the surface of the heated substrates. The air pressure inside the quartz tube was 0.2 atmospheres higher than atmospheric. The time of the deposition process of one layer was 2 min; the entire deposition process of a 10-layer film was 20 min.

Table 1. Technological parameters and properties of single-layer films grown from a solution of 10SnCl ₄ · 10Н ₂ О + 10C ₂ H ₅ OH in an amount of 3 ml for 2 min. Example No. (Substrate No.) Substrate temperature, ° С Pressure of compressed air, atm Film Resistance (R), Ohm Refractive Index (n), rel. Thickness (d), nm 1 (1) 1780 1,540 ± 0,005 70 ± 10 1 (2) 300 1660 1,570 ± 0,005 81 ± 10 1 (3) 1810 1,545 ± 0,005 75 ± 10 2 (1) 1200 1.762 ± 0.005 120 ± 10 2 (2) 500 1.1 ± 0.01 1220 1.764 ± 0.005 137 ± 10 2 (3) 1170 1,761 ± 0,005 125 ± 10 3 (1) 1400 1,540 ± 0,005 220 ± 10 3 (2) 700 1572 1,570 ± 0,005 260 ± 10 3 (3) 1450 1,545 ± 0,005 235 ± 10 4 (1) 1270 1,520 ± 0,005 120 ± 10 4 (2) 300 1370 1,570 ± 0,005 110 ± 10 4 (3) 1270 1.535 ± 0.005 135 ± 10 5 (1) 700 1,757 ± 0,005 220 ± 10 5 (2) 500 1.2 ± 0.01 850 1,760 ± 0,005 200 ± 10 5 (3) 708 1,755 ± 0,005 225 ± 10 6 (1) 1370 1,570 ± 0,005 320 ± 10 6 (2) 700 1407 1,548 ± 0,005 360 ± 10 6 (3) 1465 1.525 ± 0.005 335 ± 10 7 (1) 970 1,570 ± 0,005 200 ± 10 7 (2) 300 1010 1.541 ± 0.005 208 ± 10 7 (3) 937 1,546 ± 0,005 215 ± 10 8 (1) 570 1.765 ± 0.005 312 ± 10 8 (2) 500 1.3 ± 0.01 610 1.764 ± 0.005 330 ± 10 8 (3) 637 1.764 ± 0.005 325 ± 10 9 (1) 1170 1,540 ± 0,005 410 ± 10 9 (2) 700 1110 1,570 ± 0,005 380 ± 10 9 (3) 1237 1.525 ± 0.005 435 ± 10

Table 2. Technological parameters and properties of single-layer films grown from a solution of 9.8SnCl ₄ · 9.8H ₂ O + 10C ₂ H ₅ OH + 0.2SbCl ₃ · H ₂ O in an amount of 3 ml for 2 minutes Example No. (Substrate No.) Substrate temperature, ° С Pressure of compressed air, atm Film Resistance (R), Ohm Refractive Index (n), rel. Thickness (d), nm 10 (1) 1080 1,630 ± 0,005 74 ± 10 10 (2) 300 960 1,680 ± 0,005 82 ± 10 10 (3) 1010 1,655 ± 0,005 71 ± 10 11 (1) 400 1.852 ± 0.005 115 ± 10 11 (2) 500 1.1 ± 0.01 420 1.874 ± 0.005 124 ± 10 11 (3) 440 1.841 ± 0.005 128 ± 10 12 (1) 1100 1,630 ± 0,005 215 ± 10 12 (2) 700 1072 1.670 ± 0.005 256 ± 10 12 (3) 950 1,655 ± 0,005 229 ± 10 13 (1) 770 1,640 ± 0,005 117 ± 10 13 (2) 300 670 1,650 ± 0,005 113 ± 10 13 (3) 820 1,635 ± 0,005 134 ± 10 14 (1) 310 1.847 ± 0.005 225 ± 10 14 (2) 500 1.2 ± 0.01 350 1.870 ± 0.005 217 ± 10 14 (3) 328 1.855 ± 0.005 228 ± 10 15 (1) 779 1,660 ± 0,005 314 ± 10 15 (2) 700 807 1.658 ± 0.005 354 ± 10 15 (3) 865 1,665 ± 0,005 345 ± 10 16 (1) 670 1.670 ± 0.005 212 ± 10 16 (2) 300 610 1,661 ± 0,005 204 ± 10 16 (3) 737 1,646 ± 0,005 213 ± 10 17 (1) 270 1.865 ± 0.005 310 ± 10 17 (2) 500 1.3 ± 0.01 210 1.854 ± 0.005 327 ± 10 17 (3) 237 1.874 ± 0.005 322 ± 10 18 (1) 870 1,640 ± 0,005 417 ± 10 18 (2) 700 910 1,640 ± 0,005 385 ± 10 18 (3) 837 1.615 ± 0.005 425 ± 10

An analysis of the practical results of the studies presented in Tables 1 and 2 allows us to conclude that multilayer films consisting of alternating layers of tin dioxide (SnO ₂ ) and tin dioxide (SnO ₂ ) doped with antimony oxide (Sb ₂ O ₃ ), must be carried out at a temperature of 500 ° C and an air pressure inside the quartz tube of 1.2 atm. It is under such technological conditions that it is possible to obtain films of these compositions with a refractive index n in the range of 1.75-1.88 and quite well matching reference data equal to 1.87-1.89 [1-3].

Thus, the claimed group of inventions allows, as shown by numerous examples of testing conducted at the laboratory base of St. Petersburg State University, to obtain multilayer periodically alternating nanocrystalline films of different phase composition with a controlled film thickness and a controlled grain dispersion; to increase the productivity of obtaining such multilayer alternating nanocrystalline films of different phase composition and with high adhesion, and also allows to significantly simplify the device that implements the claimed method. In fact, a new technology has been announced for the manufacture of metallic, semiconductor and dielectric materials and devices using new nanocrystalline films with high adhesion and with different phase compositions.

Used sources

1. Suikovskaya N.V. Chemical methods for producing transparent films. L .: Chemistry, 1971, 200 p.

2. Weinstein V.M., Fistul V.I. Wide-gap oxide semiconductors. Results of science and technology, ser. Electronics and its application, 1973, pp. 108-146.

3. Ryumin V.P. Technology and application of silver and oxide-tin thin-layer coatings. L .: Energy, 1979, 118 p.

4. RF patent No. 2326818 C1, C01G 23/047, C12N 11/14, B01J 37/36, 06/20/2008.

5. RF patent No. 2233791 C2, B82B 3/00, B22F 9/30, G11B 5/845, 08/10/2004.

6. RF patent No. 2233791 C2, B82B 3/00, B22F 9/30, G11B 5/845, 08/10/2004 (prototype for the method).

7. RF patent No. 2175692 C2, C30B 23/02, 25/02, 10.11.2001 (prototype for the device).

8. Tomaev V.V., Panov M.F. Ellipsometric control of the parameters of lead selenide films during oxidation. // Phys. and chem. glass. 2006.V.32. Number 3. S.511-515.

9. Kalinina M.V., Moshnikov V.A., Tikhonov P.A., Tomaev V.V., Drozdova I.A. Temperature studies of the resistance of tin dioxide-based metal oxide semiconductors. // Phys. and chem. glass. 2003.V.29. Number 3. S.450-456.

10. Kalinina M.V., Moshnikov V.A., Tikhonov P.A., Tomaev V.V., Mikhaylichenko S.V. Temperature studies of the resistance of tin dioxide-based metal oxide semiconductors. // Phys. and chem. glass. 2003.V.29. Number 4. S.582-590.

Claims (8)

1. A method of forming multilayer nanocrystalline films with a heterogeneous interface, which consists in preparing a solution of a mixture of metal salts, aerosolizing the solution on a surface of a substrate in a carrier gas stream, removing solvent from a solution of a mixture of metal salts and forming multilayer nanocrystalline metal films on a substrate in the result of thermal decomposition of metal salts, characterized in that the surface of the substrate is preheated from a solution of a mixture of salts aerosol fog is formed to it of metals, which is transferred and deposited onto the substrate surface with a stream of oxygen-containing carrier gas, the carrier gas pressure is maintained above atmospheric, a heterogeneous interface is formed by applying a different chemical composition to the formed nanocrystalline layer of a nanocrystalline layer different from the previous one. 2. The method according to claim 1, characterized in that the surface of the substrate is preheated to a temperature in the range of 300-700 ° C. 3. The method according to claim 2, characterized in that the aerosol fog is formed using an ultrasonic generator. 4. The method according to claim 3, characterized in that the pressure of the carrier gas is maintained above atmospheric by no more than 0.3 atmospheres. 5. The method according to claim 4, characterized in that each nanocrystalline layer is formed from a solution of a mixture of metal salts containing the main component and the additive. 6. The method according to claim 5, characterized in that tin dichloride with a percentage of from 95 to 100% in a mixture of metal salts is used as the main component. 7. The method according to claim 5 or 6, characterized in that as an additive use chlorides of other metals, such as antimony, copper, cadmium, indium, platinum, palladium, gold, silver, aluminum, zinc, nickel, erbium with a percentage no more than 5% in relation to the main component. 8. A device for forming multilayer nanocrystalline films with a heterogeneous interface, including a quartz reactor with substrates, a heater for heating the substrates, two isolated cuvettes for solutions of mixtures of metal salts, characterized in that each of the two isolated from each other cuvette is equipped with ultrasonic generator, at the inlet the device is equipped with a compressor and a magnetic valve for adjusting the overpressure in the reactor, an electric motor is connected to the substrate through the rod, the device is equipped with a residual gas converter, the quartz reactor is made in the form of a pipe, on both sides of which there are metal bushings.

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