Method of making probes with carbon nanotubes
SUBSTANCE: invention relates to vacuum technology and the technology of making carbon nanotubes, such as carbon nanotubes at ends of probes, which are used in probe microscopy for precision scanning. The method of making probes with carbon nanotubes is realised by depositing carbon films with nanotubes through magnetron sputtering in a vacuum at direct current of 100-140 mA using a carbon target with a nanotube growth catalyst. Work pieces of the probes are put into a vacuum installation. A carbon film with nanotubes is then sputtered in a residual atmosphere of inert gas.
EFFECT: invention allows for obtaining probes with carbon nanotubes, lying perpendicular the surface of the probe, in required amounts without using explosive substances and complex devices.
The invention relates to the field of vacuum equipment and technologies for production of carbon nanostructures such as carbon nanotubes at the tip of the probe. They can be used in probe microscopy as a scanning probe for precision scanning, a noticeable improvement in the quality control samples and for nanolithography.
A method of obtaining a particularly sharp probes, based on the method of field emission , which is that tungsten nanofibres grown on the silicon tip of the probe when exposed to field emission in a high vacuum chamber, combined with an electronic microscope. Two preparations of electrochemically etched tungsten probes were placed on two of the micromanipulator. The flow of the working gas - tungsten exurbanite at a temperature of 35°C and the inclusion of a constant field emission induced growth of tungsten nanofibers on one of the blanks probes serving as the cathode. The length of the resulting nanofibers depends on the duration of the exposure field. However, the known method is poorly monitored and involves the formation of a strong tip of the probe with a small number of defects.
Of the known methods, the closest to the technical essence is a method of producing carbon nanotubes at the tip of the probe by khimicheskogo the vapour deposition , adopted for the prototype. In this way offers pre electrochemically sharpened tungsten probe heated to a temperature of 700°C, first in argon, and then in the environment of ethylene. Thus, the entire surface of the probe is covered with a lot of nanotubes, which are then mostly travliata the electron beam in the electron microscope. Although this method ensures the formation of nanotubes at the tip of the probe, however, it is poorly controlled and characterized by complexity and multi-stage.
The technical result aimed at reducing mnogostadiinost and reproducibility, is the deposition of nanotubes directly on the tip of the probe. This is achieved by the fact that the carbon film is applied by magnetron sputtering in a vacuum at a constant current of 100-140 mA using the carbon target with a catalyst for the growth of nanotubes.
Magnetron sputtering is optimal for the application of nanotubes at the tip of the probe, as it ensures the locality of spraying and growth of nanotubes. A necessary condition for sputtering is a high vacuum, which provides defectless formed nanotubes. When the supply current less than 100 mA spraying weak and nanotubes are not formed, and when the coil is energized more than 140 mA intense sputtering, the quality of carbon laid down is, and accordingly nanotubes, falling.
This method was implemented using research vacuum installation MRH-3 .
Figure 1 shows a diagram of the experimental setup, consisting of a vacuum chamber 1, the magnetron node with the target 2, the sample holder 3 and the plate with the probe 4. As a target, we used a disk of pure graphite for cores of reactors with metal catalysts Y, Ni (sometimes Co, Fe). The square surfaces of the component parts of the target was mapped as C:Y:Ni=94:5:1. After the preliminary pumping into the chamber was snarled working gas is argon. As preparations probes were used platinum-iridium, tungsten and gold-kovarova wire. The wire is cut into pieces with a length of 2-3 cm, were fixed in the sample holder at a distance of 3-5 cm above the target.
These billet probes were placed in the vacuum installation. It was further held deposition of carbon in the residual atmosphere of inert gas. Electrical discharge: constant current power targets 100-140 mA, the discharge voltage 150-400 C.
The resulting probes with nanotubes were investigated by scanning electron microscope (SEM), and conducted comparative testing with probes without nanotubes by scanning tunneling microscope (STM).
Method REM investigated the tips of the probes on most probes b is detected whether nanotubes with a diameter of 10 nm, arranged perpendicularly to the surface of the probe. Figure 2 presents the SEM image of the tip of a platinum-iridium tip with the increase in 170 times. Under higher magnification of 30,000 times (figure 3) at the tip of the probe were detected nanotubes with a diameter of ~30 nm.
According to the results of comparative testing of the received probes and probes without nanotubes was confirmed by high resolution probes with nanotubes up to atomic resolution. 4 shows the STM image of the crystal lattice vysokoorientirovannogo pyrolytic graphite, received platinum-iridium tip-nanotube.
So using the STM method was shown the suitability of the probes with the nanotubes to conduct nanolithography (figa) - the diameter of the formed channels 20 nm or less (figb).
Figure 6 shows the results of scanning a conventional platinum-iridium electrode (figa) and platinum-iridium tip-nanotube (figb) of the test sample from the DVD. It is well visible that figb spelled out all fields with high resolution, since the small diameter of the nanotubes allows you to penetrate even in the area between the tracks of the DVD, and a small amount of rounding of the tip of the nanotube provides high resolution at each point of the scan. Therefore, the tip-nanotube provides significantly better control the quality of the VA samples compared to conventional probes.
Thus, the proposed method allows to obtain probes with carbon nanotubes with a diameter of 10 nm and positioned perpendicular to the surface of the probe in the required quantities without the use of hazardous substances (hydrocarbons, etc.) and complex installations. In addition, the resulting probes are sturdy, multitechnology and durability.
 AVN. Tau, J. T. L. Thong "Fabrication of super-sharp nanowire atomic force microscope probes using a field emission induced growth techniques". // Review of scientific instruments, v. 75, No. 10 (2004), 3248-3255.
 Y. Shingaya, T. Nakayama, M. Aono "Carbon nanotube tip for scanning tunneling microscopy". // Physica B 323 (2002), 153 to 155.
 Antonenko S. C., S. Maltsev., EN 2218299 C1, 17.07.2002.
The way to obtain probes with carbon nanotubes, consisting in the application of carbon films with nanotubes at the tip of the probe, wherein the carbon film is applied by magnetron sputtering in a vacuum at a constant current of 100-140 mA using the carbon target with a catalyst for the growth of nanotubes.
FIELD: electronic engineering; materials for miscellaneous semiconductor devices using gallium arsenide epitaxial layers.
SUBSTANCE: intermetallic compounds chosen from group incorporating tin arsenide SnAs, palladium antimonide PdSb, manganese polyantimonide Mn2Sb, nickel stannate Ni3Sn2, nickel aluminate Ni2Al3, nickel germanate Ni2Ge, and cobalt germanate Co2Ge are used as materials of substrates for growing gallium arsenide epitaxial layers.
EFFECT: enhanced structural heterogeneity of gallium arsenide layers being grown.
FIELD: non-organic chemistry, namely triple compound of manganese-alloyed arsenide of silicon and zinc arranged on monocrystalline silicon substrate, possibly in spintronics devices for injection of electrons with predetermined spin state.
SUBSTANCE: electronic spin is used in spintronics devices as active member for storing and transmitting information, for forming integrated and functional micro-circuits, designing new magneto-optical instruments. Ferromagnetic semiconductor hetero-structure containing zinc, silicon, arsenic and manganese and being triple compound of zinc and silicon arsenide alloyed with manganese in quantity 1 - 6 mass % is synthesized on substrate of monocrystalline silicon and has formula ZnSiAs2 : Mn/Si. Such hetero-structure is produced by deposition of film of manganese and diarsenide of zinc onto silicon substrate and further heat treatment of it.
EFFECT: possibility for producing perspective product for wide usage due to combining semiconductor and ferromagnetic properties of hetero-structure with Curie temperature significantly exceeding 20°C and due to its compatibility with silicon technique.
3 ex, 2 dwg
FIELD: semiconductor technology; production of microelectronic devices on the basis of substrates manufactured out of III-V groups chemical element nitride boules.
SUBSTANCE: the invention is pertaining to production of microelectronic devices on the basis of substrates manufactured out of III-V groups chemical element nitride boules and may be used in semiconductor engineering. Substance of the invention: the boule of III-V groups chemical element nitride may be manufactured by growing of the material of III-V groups the chemical element nitride on the corresponding crystal seed out of the same material of nitride of the chemical element of III-V of group by epitaxy from the vapor phase at the speed of the growth exceeding 20 micrometers per hour. The boule has the quality suitable for manufacture of microelectronic devices, its diameter makes more than 1 centimeter, the length exceeds 1 millimeter, defects density on the boule upper surface is less than 107 defects·cm-2.
EFFECT: the invention ensures manufacture of the microelectronic devices of good quality and above indicated parameters.
102 cl, 9 dwg
SUBSTANCE: directly micellar dispersion of reducer is prepared on base of water solution of functional SAS (surface active substances) of anion or cation types with counter ions of alkali metals and halogens. Ions of metals are reduced in system of direct micelles by barbotage of reaction mixture with inert gas. To stabilise produced nanoparticles chloride of s-dodecylisothiouranyl is added into reaction mixture.
EFFECT: simplification of production of particles with upgraded magnetic susceptibility.
6 dwg, 6 ex
SUBSTANCE: to treat patient suffering from hepatitis B or C, body fluid is sorbed by means of flowing through device comprising suspension preparation assembly equipped with ultrasonic dispergator wherethrough nanoparticle suspension shall flow as nanofraction of cobalt ferrospinel CoFe2O4 in spiritus and shall be mixed with body fluid infected by viruses of hepatitis B or C. The device also comprises magnetic filter with entry zone wherein a uniform magnetic field is established rough filtration zone where gradient magnetic field is established from axially magnetised bushing, fine filtration zone wherein alternating high-gradient magnetic field is established. Body fluid, which is free from nanoparticles with sorbed viruses is delivered into vessel for clean body fluid accumulation.
EFFECT: inventions enable to improve sorbtion efficiency relative to antigens and viruses over a wide range of concentrations and concentration weakening in sorbing solution below the limit of poor and positive reaction.
9 cl, 2 dwg
FIELD: instrument making.
SUBSTANCE: invention is related to methods for nondestructive check of semiconductor and low-size semiconductor nanostructure parametres. Iin method for contactless definition of quantised Hall resistance of semiconductors, including semiconductor cooling down to helium temperatures, its exposure to alternating permanent magnetic field, induction vector B of which is perpendicular to surface of sample, and additionally to alternating magnetic field that varies with sonic frequency, having amplitude that is much less than B and induction vector directed parallel to vector B, radiation of sample with microwave radiation of specified frequency in direction, which is parallel to induction vector B of permanent magnetic field, selection of radiation frequency less than frequency of charge carriers collisions with atoms of semiconductor, additional cooling of semiconductor down to temperature below 2K, registration of signal proportional to second derivative of microwave radiation capacity depending on magnetic field B, measurement of magnetic field value that corresponds to minimum of reflected signal, and definition of quantiszed Hall resistance in wide range of quantising magnetic fields by means of calculations according to given formula.
EFFECT: wider application field.
SUBSTANCE: conducting molecular structure comprises a dielectric matrix and conducting filler. Molecules of at least one component of the dielectric matrix have composition and structure which allow for intramolecular electron transport. The conducting filler is in form of conducting particles or electrodes, the length of which in at least one dimension lies in the nanometre range. Concentration of particles of the conducting filler prevents their percolation, resulting in separation of particles. The particles are electrically connected to each other by molecular conductors.
EFFECT: increased conductivity of composite material, reduced filler concentration and wider functional capabilities of obtained material, and wider capabilities of the method of making molecular structures due to increased means of creating electric field.
2 cl, 1 dwg
SUBSTANCE: invention relates to powder metallurgy, particularly to receiving of constant powder-like magnets with nanocrystalline structure. It can be used at manufacturing of high-energy constant magnets on the basis of natural iron-containing powder material. Initial powder material, containing, wt %: α-Fe 25-50, Fe2O3 30-75, FeO 0,2-2, attendant admixtures - the rest, it is treated in high-energy mill, to which there are loaded actuating mediums in the forms of steel balls. Treatment is implemented at value of energy-intensity, equal to 12-20 watt/g., during the time, required for transformation of initial powder material into intermediate powder material, containing, wt %: FeO 50-80, α-Fe 10-35, amorphous phase 10-30, attendant admixtures - the rest. Intermediate material is pressed at 300-600 MPa with receiving of compacted samples and it is implemented magnetothermal treatment of received samples in vacuum furnaces at residual pressure not less than 10-1 mm of mercury at annealing temperature, equal to 200-400°C, during time not less than 1 h and at value of magnetising force from 3 kE up to 7 kE.
EFFECT: receiving of hard-magnetic composite material with nanocrystalline structure containing, wt %: Fe3O4 - 65-80%, α-Fe - 35-20%, attendant admixtures - the rest, with magnetic and crystalline texture with keeping of high magnetic properties.
9 cl, 1 tbl
FIELD: physics, photography.
SUBSTANCE: invention is related to technology of preparation of photographic emulsions for camera photomaterials. In such technologies they often use method of microcrystal doping with ions of heavy metals to improve sensitometric characteristics of emulsion layers. Suggested method of photoemulsion manufacturing with application of doping consists in performance of double-jet crystallisation of silver nitrate and potassium bromide solutions, interruption of process, single-stage introduction of iridium compound solution as dopant and completion of double-jet crystallisation process. Besides process is interrupted for the period of 30-120 sec. before single-stage introduction and delay of 30-120 sec. after introduction of iridium compound solution. Iridium compounds used are complex compounds from the group K2[IrBr6], K2[IrCl6], K2[IrBr5Cl], K2[lrCl5Br] in concentration from 10-7 to 10-9 mole/mole Ag.
EFFECT: improved sensitometric characteristics due to increase of duration of electronic stage of hidden image centers creation and more efficient use of photoelectrons produced in process of exposure.
3 cl, 1 tbl, 15 ex
SUBSTANCE: method involves primary electric spark machining of the surface of a metal base with a composite electrode. The coating formed undergoes secondary machining with an electrode made from carbon-containing material. Primary and secondary machining is carried out under the following conditions: 0.01≤Pi≤10. 500≤N≤5400000, 0.0185≤f/N≤0.1, where Pi - is energy of a single pulse discharge, J, f - is the frequency of current pulses, Hz, N - the number of current pulses during electric spark machining.
EFFECT: obtaining multifunctional coatings with good operational properties on metal surfaces, working under loading in extreme operating conditions, with increased continuity, wear resistance and heat resistance and less roughness, and less and more stable coefficient of friction.
3 cl, 3 tbl, 1 ex
SUBSTANCE: beforehand hardened alloy subject to cold deformation by means of multiple rolling with providing of total veritable degree of deformation e≥0.6 and annealing at temperature 250-550°C. Rolling is implemented with application to crumple zone of pulse current, parametres of which are variated in following intervals: current density 60-300 A/mm2, pulse-repetition frequency 400-1200 Hz and pulse duration 40-200 microsecond. Each following single clamping at multiple rolling is implemented with change of direction. Rolling rate amounts 20-250 mm/s. Parametres of pulse current is variated at each stage of deformation, herewith it is used unidirectional pulse current.
EFFECT: creation in alloys of regulated parametres of nanocrystalline structure with increased complex of mechanical and functional properties, reduction of laboriousness of technical process for receiving of semi-finished products.
5 cl, 1 ex
SUBSTANCE: invention claims method of obtaining nano-sized powders based on tricalcium phosphate and hydroxylapatite system for ceramicbiomaterial synthesis. Invention concerns calcium phosphate ceramic materials intended for manufacturing of bone grafts and/or defect area replacement for various bone pathologies. Humid powders obtained by chemical reaction are flushed by organic fluids to remove water excess. Ultradisperse calcium phosphate powders with specific surface area of over 90 m2/g are obtained after drying and thermal processing. Nano-sized powder composition is close to natural bone tissue (corresponding to hydroxylapatite and tricalcium phosphate system). High specific surface of powders allows for their application in obtaining biomaterials with fine dispersed or nanocrystalline structure.
EFFECT: reduced aggregation degree, enhanced specific surface.
SUBSTANCE: invention can be used for preparation of detonation nanodiamonds suspension with positively charged particles. The nanodiamonds powder is dispersed with ultrasound in the saturated solution of polyvalent metals salts, the obtained mixture undergoes the thermal treatment up to drying, heated at 380-520 K during 30 min and washed with water up to ion absence in the wash water.
EFFECT: obtaining of the nanodiamonds with positively charged particles in the water suspensions at low process time and decrease of reagents toxicity.
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.