Method of making ohmic contact to gaas
SUBSTANCE: in the method of making an ohmic contact to GaAs, a mask is formed on the surface of an n-GaAs plate, having a doped layer, in order to carry out a lift-off lithography process. To clean the surface in the windows of the mask, the n-GaAs plate is treated in aqueous H2SO4 or HCl solution and then washed in deionised water and dried. Further, via electron-beam and/or thermal evaporation in a vacuum at residual pressure lower than 5x10-6 torr, Ge and Cu are deposited with total thickness of 100-500 nm and weight content of germanium in the double-layer composition equal to 20-45%. Further, in a single vacuum cycle, the n-GaAs plate undergoes first thermal treatment at temperature T1=150-460°C in an atmosphere of atomic hydrogen with hydrogen atom flux density on the surface of the plate equal to 1013-1016 at.cm2 s-1. The n-GaAs plate is removed form the vacuum chamber, and after removing the mask, undergoes second thermal treatment in an atmosphere of an inert gas or in a vacuum at temperature T2=280-460°C for t=0.5-30 min.
EFFECT: lower value of reduced contact resistance.
2 cl, 1 dwg
The invention relates to the technology of microelectronics, in particular to a technology for discrete devices and integrated circuits based on semiconductor compounds AIIIBVin particular to the creation of ohmic contacts (OK) for drain-source field-effect transistors with Schottky barrier, as well as heterostructure transistors with high electron mobility.
Ohmic contacts must have a low ohmic resistance, smooth surface morphology pads, high thermal stability parameters, small depth of interaction metallization contact with the semiconductor, and low cost (Raskin A.A., Shalimov S. Foreign electronic equipment. 1990, No. 12, p.32 47).
Known methods of forming low resistance ohmic contacts to n-GaAs using a metallization system comprising the following components: Au, Ge and Ni. Gold and germanium are deposited on the semiconductor in the form of a film eutectic AuGe alloy (88% Au and 12% Ge) and a layer of Ni (Pietrovska A., Gulvatch A., Peloua G. // Solid St. Electron, 1983, v.26, p.179), or as three separate films of these elements (Bruce R. A. Piercy G.R. // Solid St. Electron. 1987, v.30, No.7, p.729). Moreover, in the latter case, the ratio of film thickness of Ge and Au is chosen such as to correspond to the eutectic composition AuGe. Thus the total thickness of the deposited films Au/Ge is in the range of 10-150 nm, and the thickness of the Nickel layer in the range of 10-50 nm. After deposition, the contact is subjected to heat treatment. In the annealing process is the formation of low-melting alloy and liquid-phase mixing of Au, Ge, Ni and GaAs.
The disadvantages of these methods is low enough given the contact resistance, the depth of recrystallized region OK (~0.1 ám), low thermal stability of electrical parameters of contact, due to the presence of the contact fusible phase AuGa with a melting point of 370°C, the developed relief of the surface of the pad, as well as its uneven edge, the high cost of OK, which is due to the use of gold.
A known method of making low resistance contact to GaAs (Jim-Tsuen Lai, Joseph Ya-Min Lee/Pd/Ge ohmic contacts to n-type GaAs formed by rapid thermal annealing Appl. Phys. Lett. 64(2), 1994, pp.229-237), which use the metallization system, consisting of a series of sputtered films of Pd and Ge. Nespravnou Pd/Ge ohmic contact is formed by solid-state diffusion of atoms Germany in GaAs through a layer of palladium with education signalisierung n+layer and shows the best thermal stability of electrical parameters and smoother the surface morphology of the contact compared with Au/Ge/Ni equivalent.
The disadvantages of this contact can be attributed to a higher contact resistance than the structure with Au/Ge/Ni, and the complexity of its formation in a typical route for the fabrication of integrated circuits due to the presence on the surface of the ohmic contact reactive and oxidize film Germany.
Known methods in which to obtain better electrical contact to the surface of the ohmic contact Pd/Ge deposited gold film (Rnno // On the low resistance of the Au/Ge/Pd ohmic contact to n-GaAs // J.Appl. Phys., 79(8), 1996) or copper (US patent No. 7368822, IPC H01L 23/48, publ. 06.05.2008). The advantages of these methods include low value of contact resistance. The disadvantages of the method include low thermal stability of electrical parameters OK due to the penetration of the rapidly diffusing atoms of gold and copper in GaAs.
A method of obtaining thermally stable ohmic contact to GaAs (Aboelfotoh MO / Microstructure characterization of Cu3Ge/n-type GaAs ohmic contacts // J.Appl. Phys., 76(10), 1994), whereby to obtain a OK system is used for metallization on the basis of the two-layer film Ge/Cu (thickness are chosen so as to form a composition of Cu3Ge), which forms ohmic contact with both n-and p-type GaAs. These contacts are characterized by high thermal stability of electrical parameters, as well as low production costs, due to lack of precious metals in the composition is OK.
However the com of this method is the instability obtain a low value of contact resistance, due to uncontrolled oxidation of copper and/or Germany during the inter-operation of polerowanie in the air, resulting in non-repeatable processes in the formation of OK during annealing.
A known method of manufacturing a contact-based films Ge/Cu (..Aboelfotoh, S.Oktyabrsky, and J.Narayan / Electrical and microstructural characteristics of GeCu ohmic contacts to n-type GaAs // J.Mater. Res., Vol.12, No.9, 1997, pp.2325-2332), essentially the most close to the proposed technical solution chosen for the prototype. The method consists in the following. On the surface of the plate n-GaAs (100) with the concentration of electrons in the epitaxial layer is n=3×1017cm-3with the aim of implementing the process of the inverse lithography mask is formed. To clean the surface in the Windows of the mask, the GaAs wafer is processed in an aqueous solution of HCl (1:1) and then rinsed in deionized water and drying in a stream of nitrogen. Then by the method of electron beam evaporation in vacuum at a residual pressure atmosphere 10-7Torr is performed layer-by-layer films deposited on Ge and Cu with a total thickness of 0.2 μm and the thickness of the Ge film, which sets the mass content of Ge in the metallization equal to 40%. Thereafter, the GaAs wafer is subjected to first heat treatment in a single vacuum cycle at T1=100°C for t=60 minutes and Then the plate is removed from the vacuum chamber and after removal of the mask is exposed to second the second heat treatment at a temperature T 2=400°C for t=30 min in vacuum at a residual pressure atmosphere 10-7Torr. Conducting a first annealing in a single vacuum cycle allows you to start the formation of the contact conditions, when the surface of the deposited films has not yet oxidized.
The disadvantages of this method include low enough the value of a given contact resistance.
The main technical objective of the proposed method is to reduce the values shown in the contact resistance.
The main technical problem is achieved by a method of making ohmic contact to GaAs, including the creation on the surface of the plate n-GaAs mask for the implementation of the inverse process of lithography, deposition of Ge and Cu on the plate surface of n-GaAs, the first heat treatment in a single vacuum cycle with the deposition process, the extraction plate n-GaAs from the vacuum chamber, removing the mask and the second heat treatment, characterized in that the first heat treatment is carried out in an atmosphere of atomic hydrogen at a temperature of from 150 to 460°C and flux density of hydrogen atoms on the plate surface of the n-GaAs equal to 1013-1016at.·cm-2·with-1the deposition of Cu and Ge are performed simultaneously or alloy CuGexor from two independent sources of Cu and Ge to form a thin film CuGexwhere x=0,2-0,45.
In the particular case of osaid the Ge and Cu, and first heat treatment is carried out in a vacuum chamber at a pressure of residual atmosphere of less than 5×10 -6Torr.
Conducted by the applicant's analysis of the level of technology has allowed to establish that the analogs are characterized by the sets of characteristics is identical for all features of the proposed device are missing.
Search results known solutions in this and related areas of technology in order to identify characteristics that match the distinctive features of the prototype of the invention has shown that they do not follow explicitly from the prior art.
Of certain of applicant's prior art there have been no known effect provided essential features of the invention transformations on the achievement of the technical result. Therefore, the invention meets the condition of patentability "inventive step".
The figure shows the dependence of the given contact resistivity ρ of ohmic contacts to GaAs with 45%germanium concentration from the temperature of the first heat treatment T1obtained by the method-prototype (1) and proposed method (2).
The proposed method consists in the following. On the surface of the plate n-GaAs having a doped layer, with the aim of implementing the process of the inverse lithography mask is formed. To clean the surface in the Windows of the mask plate n-GaAs is processed in an aqueous solution of H2SO4or HCl followed the th its rinsed in deionized water and drying. Then using methods of electron-beam and/or thermal evaporation in vacuum at a residual pressure of less than 5×10-6Torr is the deposition of Ge and Cu total thickness of 100-500 nm with a mass content of germanium in a two-layer composition, equal 20-45%. Then, the plate n-GaAs in a single vacuum cycle is subjected to first heat treatment at a temperature T1=150-460°C in an atmosphere of atomic hydrogen at a flux density of hydrogen atoms on the surface of the plate equal to 1013-1016at.·cm-2·c-1. Then, the plate n-Ga-As extracted from the vacuum chamber and after removal of the mask is subjected to a second heat treatment in an atmosphere of inert gas or in vacuum in the temperature range T2=280-460°C for t=0.5 to 30 minutes
The minimum and maximum values of mass content of Ge in the two-layer composition the 20% and 45%, respectively, are determined by the fact that at smaller or larger values of contact resistance OK becomes unacceptable regardless of the method and its modes of the first and second heat treatment.
The minimum value of the flux density of hydrogen atoms on the surface of the plate equal to 1013at.·cm-2·with-1defined by the fact that at lower values is not achieved technical result of the invention in connection with the competition between the processes of oxidized who I am and deposition OK gases, present in the residual atmosphere in the vacuum chamber, and its reduction with hydrogen atoms. The maximum value of the flux density of hydrogen atoms on the surface of the plate equal to 1016at.·cm-2·with-1the marginal technical capabilities available sources of atomic hydrogen.
The minimum temperature of the first heat treatment T1=150°C is determined experimentally established facts, according to which at a lower temperature is not observed differences in the value of the given contact resistance obtained by the prototype method and the proposed method. The maximum value of the temperature of the first heat treatment T1=460°C is determined by the maximum possible temperature, which is used in a GaAs microelectronics.
The temperature and time intervals of the second heat treatment (T2=280-460°C, t=0.5 to 30 min) sets the minimum and maximum temperature budgets required for the formation of OK with the minimum value of the given contact resistance.
The example demonstrates the technical result achieved by the proposed method on how the prototype, and the ability to achieve a technical result in a wide range of temperatures first termoobrabotki and in atomic hydrogen.
Used ion-doped wafer of n-Guas (100) with the concentration of electrons in the layer thickness of 0.12 μm, equal to n=2×1017cm-3. On the surface of the plate n-GaAs was formed a two-layer dielectric mask, which was opened window with a negative angle of inclination of the walls. Before deposition of Ge and Cu to clean the surface and remove native oxides of arsenic and gallium plate n-GaAs were processed in an aqueous solution of H2SO4(1:10) for 3 minutes, subsequently rinsed in deionized water and drying in a stream of nitrogen. Then, the plate n-GaAs was divided into two parts and loaded into the vacuum chamber. On both parts of the plate using a sequential deposition of Ge and Cu was formed a two-layer composition with a mass content of germanium equal to 45%. The residual pressure of the atmosphere was 4×10-6Torr. Immediately after deposition, by analogy with the method prototype, the first part of the plate n-GaAs subjected to first heat treatment in vacuum at T1=75°C for t=60 minutes thereafter, in accordance with the proposed method, the second part of the plate n-GaAs subjected to first heat treatment in a similar way, but in an atmosphere of atomic hydrogen at a pressure of molecular hydrogen p=10-4Torr and flux density of the hydrogen atoms of 1015at.·cm-2·with-1. Steelstone n-GaAs is removed from the vacuum chamber, removed the mask, which led to the formation topology, OK. Then both parts of the plate n-GaAs simultaneously subjected to a second heat treatment in the setting of rapid thermal annealing at a temperature T2=400°C for t=60 seconds in an atmosphere of pure nitrogen.
This sequence was repeated 5 times for various temperatures of the first heat treatment (T1=75-400°C). The value of the given contact resistance was measured by the method of transmission lines 10 tests, and then were averaged.
From the figure, which shows the dependencies listed in the contact resistance ρ from the temperature of the first heat treatment T1for OK, obtained by the method prototype, and OK, obtained by the proposed method, it is seen that the formation of OK for the proposed method at temperatures above T1=150°C can reduce the value of a given contact resistance in 2-2,5 times, about how the prototype. This is achieved due to the impact of hydrogen atoms that are chemically active particles with reducing properties, reduce the rate of oxidative reactions on the surface OK during the first heat treatment in vacuum. In addition, the first heat treatment active recovery environment (atomic hydrogen), you will increase is more than an order of magnitude, the residual pressure of the atmosphere in the vacuum chamber relative to the method prototype which is heat treatment, which reduces the requirements on the vacuum system and reduces the duration of pumping.
When forming the ohmic contact to GaAs p-type conductivity similar results were obtained.
1. Method of making ohmic contact to GaAs, including the creation on the surface of the plate n-GaAs mask for the implementation of the inverse process of lithography, deposition of Ge and si on the plate surface of n-GaAs, the first heat treatment in a single vacuum cycle of deposition layers, removing the plate n-GaAs from the vacuum chamber, removing the mask and the second heat treatment, characterized in that the first heat treatment is produced in an atmosphere of atomic hydrogen at a temperature of from 150 to 460°C and flux density of hydrogen atoms on the plate surface of the n-GaAs equal to 1013-1016ATM-2with-1and the deposition of si and Ge are performed simultaneously or alloy CuGexor from two independent sources si and Ge to form a thin film CuGexwhere x=0,2-0,45.
2. Method of making ohmic contact to GaAs according to claim 1, characterized in that the deposition of Ge and si and the first heat treatment is carried out in a vacuum chamber at a pressure of residual atmosphere of less than 5×10-6Torr.
SUBSTANCE: method of obtaining a thin-film copper-germanium joint involves successive deposition of Ge and Cu layers on the surface of a plate and forming a thin-film copper-germanium joint which is carried out over a time t≥0.5 minutes in an atmosphere of atomic hydrogen at temperature T=20-120°C and hydrogen atom flux density on the surface of the plate equal to 1013-1016 at.cm-2 s-1.
EFFECT: lower temperature and shorter time for obtaining a thin-film copper-germanium joint.
7 cl, 6 dwg
FIELD: material engineering.
SUBSTANCE: method of application of metallic nanolayers in chemical method involves the technology of chemical sedimentation of metals, in particular of copper (Cu) at the speed 1 μm/min with the solution temperature 50 to 60°C. As the basic copper-containing reagent for applying metallic nanolayers on silver electric contacts of silicon solar cells the inorganic copper salts are used. Technical result of the invention is the thickening of frontal electric contact of solar cell by sedimentation of metals, in particular copper, with good electric conductivity, in order to compensate or improve its increased electric conductivity.
EFFECT: increased effectiveness of solar cell operation during transformation of high-density radiation and decreased self-cost of its manufacturing.
4 cl, 4 dwg
SUBSTANCE: in the method to manufacture Cu-Ge ohmic contact on the surface of the plate n-GaAs or epitaxial heterostructure GaAs with n-layer a resistive mask is developed, fims of Ge and Cu are deposited, the first thermal treatment is carried out in the atmosphere of atomic hydrogen at the temperature from 20 to 150°C and density of hydrogen atoms flow to the surface of the plate equal to 1013-1016 at.cm-2 s-1. Plates are withdrawn from a vacuum chamber of a spraying plant, the resistive mask is removed before or after the first thermal treatment, and the second thermal treatment is carried out.
EFFECT: reduced value of the given contact resistance.
7 cl, 1 dwg
SUBSTANCE: method to metallise elements in products of electronic engineering includes application of a sublayer of a metallising coating on one of substrate surfaces with previously formed topology of elements in an appropriate product, and this sublayer is a system of metals with the specified thickness, providing for adhesion of the main layer of the metallising coating, formation of topology - protective photoresistive mask of the main layer of metallising coating, local application of the main layer of the metallising coating, removal of protective mask, removal of a part of the sublayer arranged outside the topology of the main layer of the metallising coating. Application of the sublayer of the metallising coating is carried out with the total thickness of 0.1-0.5 mcm, directly onto the specified sublayer additionally a technological layer is applied from an easily oxidable metal with thickness of 0.1-0.5 mcm, and formation of the metallising coating topology is carried out on the technological layer from the easily oxidable metal. Prior to local application of the main layer of the metallising coating a part of the technological layer is removed from the easily oxidable metal via the specified protective mask, and removal of the remaining part of the technological layer from the easily oxidable metal is carried out prior to removal of a part of the sublayer of the metallising coating arranged outside the topology of the main layer of the metallising coating.
EFFECT: increased quality of the metallising coating and reliability of electronic engineering products, improved electrical characteristics, increased yield of good products.
6 cl, 3 dwg, 1 tbl
SUBSTANCE: proposed method comprises pre-cleaning of GaSb p-junction conductance by ion-plasma etching to depth of 5-30 nm with subsequent deposition by magnetron sputtering of adhesion titanium 5-30 nm-thick layer and platinum 20-100 nm-thick barrier layer, evaporating thermally of 50-5000 nm-thick silver layer and 30-200nm-thick gold layer for contact with ambient medium.
EFFECT: reproducible ohmic contact with low specific junction resistance.
2 cl, 1 dwg
SUBSTANCE: method of depositing platinum layers onto a substrate involves pre-formation of an intermediate adhesion layer from a mixture of platinum and silicon dioxide nanocrystals on a silicon oxide and/or nitride surface. The intermediate adhesion layer with thickness 1-30 nm can be formed via simultaneous magnetron sputtering using magnetrons with platinum and silicon dioxide targets, respectively.
EFFECT: high quality of elements, processes, reliability during prolonged use, adhesion of the deposited layers to the substrate.
8 cl, 3 dwg
SUBSTANCE: method of making an ohmic contact to GaAs based on thin Ge and Cu films involves formation a mask on the surface of an n-GaAs wafer in order to perform lift-off lithography, deposition of thin Ge and Cu films onto the surface of the n-GaAs wafer, first thermal treatment in a single vacuum cycle with the deposition process, removing the n-GaAs wafer from the vacuum chamber, removing the mask and second thermal treatment. First thermal treatment is carried out in an atmosphere of atomic hydrogen at temperature 150-460°C and hydrogen atom flux density on the surface of the n-GaAs wafer equal to 1013-1016 at.cm2 s-1.
EFFECT: low value of the reduced contact resistance of the ohomic contacts made.
4 cl, 1 dwg
SUBSTANCE: method of making interconnections of a semiconductor device involves formation of a silicon structure in an insulating layer, in which semiconductor devices are formed, contact wells and trenches under future interconnection conductors, successive deposition of an adhesive-wetting layer and a solid catalyst layer at the bottom and wall of the contact wells and trenches, filling the depressions of contact wells and trenches with carbonaceous material through stimulated plasma chemical deposition of the carbon structure from the gas phase on the solid catalyst layer and planarisation of the surface of the silicon structure.
EFFECT: high thermal stability and reduced heating of IC interconnections in conditions of reduction of their cross-sectional area and high current density, low resistivity of the interconnection material compared to carbon nanotubes.
3 cl, 3 dwg
SUBSTANCE: in manufacturing method of multi-level copper metallisation of VLSIC, which involves application operations of metal and dielectric layers, photolithography and selective etching of those layers, chemical mechanical polishing of dielectric layers, to plate of silicium, which is coated with dielectric material with vertical conductors of underlying structure, which protrude on its surface, there applied is multi-layered conducting film consisting of adhesive barrier, etched and auxiliary layers; grooves are formed in auxiliary layer before etched layers by electrochemical method; copper horizontal conductors are grown inside grooves in open sections of etched layer till grooves are fully filled; the second auxiliary layer is applied to surface of plate, and in that layer holes are made to the surface of horizontal copper conductors; vertical copper conductors are grown by electrochemical method in open sections of horizontal conductors till holes for vertical conductors are fully filled; then, auxiliary layers are removed; conducting layers between horizontal copper conductors are removed; dielectric layers are applied to surface of the plate by smoothing and filling methods, and then dielectric material layers are removed above vertical conductors by means of chemical and mechanical polishing method.
EFFECT: improving quality of copper conductors.
16 cl, 11 dwg, 1 tbl
SUBSTANCE: method of forming contact drawing from nickel on silicon wafers involves formation of a dielectric film with windows, chemical deposition of nickel in said windows and formation of a nickel silicide interlayer from the gas phase during thermal decomposition of nickel tetracarbonyl vapour at temperature 200-300°C, pressure in the system of (1-10)-10-1 mm Hg and rate of supplying nickel tetracarbonyl vapour equal to 0.5-2 ml/min per dm2 of the covering surface. The nickel layer is then removed up to the nickel silicide layer through chemical etching and nickel is deposited via chemical deposition onto the nickel silicide interlayer in the window of the dielectric film.
EFFECT: invention enables formation of a transparent contact for an electroconductive layer based on nickel with low ohmic resistance, independent of the type of conductivity and degree of doping of the silicon surface.
1 ex, 1 tbl
SUBSTANCE: coating has surface tension less than 20 mN/m, wherein the coating material used is hydrolysis-resistance lacquers, and where the hydrolysis-resistant lacquers are selected from a group consisting of polyurethanes, acryl and silicones, where the coating has a random topography with roughness of less than 500 nm, preferably less than 300 nm.
EFFECT: coating prevents deposit of bacteria and improves thermal conduction of the coated material.
19 cl, 4 dwg, 2 ex
SUBSTANCE: method of producing nanocomposites involves coating nanoparticles with mean particle size from 1 nm to 100 nm with dicarboxylic acid; mixing nanoparticles coated with dicarboxylic acid with a cross-linking agent to obtain a starting mixture; mixing the starting mixture with polyester to form a polyester-based nanocomposite.
EFFECT: low crystallisation temperature and high glass-transition temperature of the nanocomposite compared to polyester.
14 cl, 7 dwg, 2 ex
SUBSTANCE: invention relates to the technology of producing modified ceramic materials based on high-temperature strength quartz glass and can be used to make articles for different purposes. The nanomodified quartz ceramic, which contains a porous ceramic base from quartz glass grains and a modifying additive from aluminium oxide, has the base in form of calcined quartz ceramic or an article made therefrom with open porosity of 7-14%, obtained via aqueous slip casting from a polydispersed suspension with grain size from 0.1 to 500 mcm, with 0.1-5.0 mcm particle content of 20-30% and 60-500 mcm particle content of 2-10%. The modifying additive in the material is α-Al2O3 nanoparticles in amount of 1.0-2.5 wt %, which are embedded in the boundary zones of quartz glass grains by mass-transfer. The α-Al2O3 nanoparticles are obtained by saturating the ceramic base with an aqueous solution of an aluminium salt Al(NO3)3·9H2O3, drying and pyrolysis at temperature 400-600°C.
EFFECT: high-temperature strength of the quartz ceramic while preserving dielectric and thermophysical properties.
1 ex, 1 tbl
SUBSTANCE: in the method for chemical-mechanical polishing of semiconductor materials, involving subjecting the treated surface to the action of a mechanical load and a polishing composition containing an aqueous suspension of abrasive particles and an iodine-containing component, according to the invention, the iodine-containing component is iodine in form of its solution in ethyl alcohol, concentration of abrasive particles in the aqueous suspension ranges from 15 to 20 wt %, concentration of iodine in the alcohol solution ranges from 0.1 to 1 wt %, wherein content of the alcohol solution of iodine in the composition ranges from 1 to 15 wt %. The abrasive particles in the composition primarily contain zeolite NaX particles or silicon dioxide particles obtained by burning silicon tetrachloride in low-temperature oxygen and hydrogen plasma, wherein the mean particle size of the abrasive ranges from 10 to 1000 nm.
EFFECT: high quality of the polished surface.
SUBSTANCE: object with given geometric parameters is formed on the surface of materials using a focused ion beam. First, (n×n) markers are written on the surface of the object on a square or rectangular grid using a focused ion beam and the shift from given coordinates of markers is determined, after which a mathematical model of the surface is formed based on the obtained data and approximation of the degree (n-1). In the simplest case, the mathematical model of the surface is formed based on data of four markers and linear approximation; the model is corrected using known data on the geometry of the surface. According to the mathematical model of the surface, mechanical and electronic combination of ion and electron optics is carried out and an object with given geometric parameters is formed on the surface of the material using a focused ion beam.
EFFECT: 7 to 18-fold increase in accuracy of forming an object with nanometre dimensions on the surface of material and high technological effectiveness of the method of forming such objects.
3 cl, 11 dwg
SUBSTANCE: invention relates to the technology of producing detergents and cleaners and more specifically to methods of producing surfactants. The method of modifying surfactant properties involves adding ultrafine carbon particles with size from 2 to 200 nm and effective specific surface area of not less than 700 m2/g to a saturated solution or concentrate of the surfactant. The weight content of ultrafine carbon particles in the obtained mixture ranges from 0.3 to 10%. The obtained mixture is stirred until complete saturation of the ultrafine carbon particles with the saturated solution or concentrate of the surfactant. After mixing the mixture of ultrafine carbon particles with the surfactant, the mixture is heated to temperature lower than the boiling point of the mixture. Heating is carried out for not less than 30 minutes, followed by filtration, drying and vacuum treatment of the obtained product.
EFFECT: invention increases surface activity and penetrating power of a surfactant with minimal expenses, high cleaning efficiency of the surfactant, simple process of modifying surfactant properties.
5 cl, 2 ex
SUBSTANCE: in the present method, biopolymer starting material and a plasticiser are fed into the feeding zone of an extruder having an auger configuration such that the biopolymer starting material, particularly starch, in the extruder undergoes processing by shearing forces, and a cross-linking agent is fed into the extruder on the process scheme downstream the feeding zone. The method is characterised by output higher than or equal to 1.0 metric ton of the product per hour. The biopolymer starting material and plasticiser are preferably fed into the feeding zone separately. The extruder in the feeding zone can have single-turn elements. Temperature in the intermediate section of the extruder is not higher than 100°C. Configuration of the auger can include two or more sealing sections for water vapour. Shearing forces in the first section of the extruder can be greater than shearing forces in the neighbouring second section of the extruder lying on the process scheme downstream the first section. Water can be fed into the post-reaction section lying after the position in which the cross-linking reaction has finished in order to improve operational characteristics of the head.
EFFECT: method enables to obtain cross-linked nanoparticles of a uniform size, having high molecular weight and also enables to manipulate molecular weight of a protective colloid.
38 cl, 3 dwg, 2 tbl, 10 ex
SUBSTANCE: invention relates to engineering ceramics and can be used to make structural components operating under high mechanical loads. The ceramic-matrix composite material, having a hardened reinforcing component in form bundles of carbon filaments coated with a layer of silicon carbide, and a silicon carbide-based matrix, contains carbon filaments inside bundles joined with each other by a carbon inter-filament phase which is reinforced with carbon nanotubes. The silicon carbide layer contains nanosized grains and the matrix further contains free silicon. When producing the ceramic-matrix composite materials, bundles of carbon filaments are treated under the action of ultrasonic vibrations with a suspension containing 2-8 wt % carbon nanotubes and 5-20 wt % polymer binder in an organic solvent, after which a polymer layer is then deposited onto the bundles via treatment thereof with a suspension containing 10-30 wt % polymer binder and 3-15 wt % thermal expanded graphite. Synthesis of the matrix and silicon carbide layer containing nanosized grains on the bundles is carried out through carbonisation and siliconisation.
EFFECT: obtained material has low porosity, high flexural strength and impact viscosity; production method is suitable for mass economic manufacture of articles.
3 cl, 3 tbl, 6 ex, 2 dwg
SUBSTANCE: invention refers to nanomaterials. Natural ore containing the following components, wt %, is used as catalyst for obtaining carbon nanotubes from methane-containing gases: manganese oxides 7÷43, iron oxides 3÷29, and the rest - up to 100.
EFFECT: invention allows simplifying the catalyst obtaining procedure and reducing the cost of nanotubes made using methane-containing gases.
FIELD: process engineering.
SUBSTANCE: invention relates to production of magnetic iron-bearing nanoparticles to be used in medicine. Proposed method comprises cultivating bacteria Klebsiella oxytoca educed from sapropel of Borovoe Lake, Krasnoyarsk Region, and growing of biomass Then, centrifugation is performed to produce precipitate bearing ferrihydrite and biomass is destructed by ultrasound to isolate ferrihydrite magnetic nanoparticles. Note here that biomass cultivation and growing are executed using iron citrate for 7-10 days to produce precipitate of bacterial cultures. After biomass destruction, precipitates are centrifuged, washed by water and acetone, and treated with NaOH to produce 20%-solution. Then, hatching is performed for an hour to wash precipitates with distilled water with addition of NaCl to neutral pH. Thereafter, precipitates are isolated, washed to produce stable aqueous sol based on ferrihydrite nanoparticles and obtained sol is racked.
EFFECT: stable aqueous sol based on ferrihydrite nanoparticles.
4 dwg, 2 tbl
FIELD: carbon materials.
SUBSTANCE: weighed quantity of diamonds with average particle size 4 nm are placed into press mold and compacted into tablet. Tablet is then placed into vacuum chamber as target. The latter is evacuated and after introduction of cushion gas, target is cooled to -100оС and kept until its mass increases by a factor of 2-4. Direct voltage is then applied to electrodes of vacuum chamber and target is exposed to pulse laser emission with power providing heating of particles not higher than 900оС. Atomized target material form microfibers between electrodes. In order to reduce fragility of microfibers, vapors of nonionic-type polymer, e.g. polyvinyl alcohol, polyvinylbutyral or polyacrylamide, are added into chamber to pressure 10-2 to 10-4 gauge atm immediately after laser irradiation. Resulting microfibers have diamond structure and content of non-diamond phase therein does not exceed 6.22%.
EFFECT: increased proportion of diamond structure in product and increased its storage stability.