Method of growing germanium monocrystals
FIELD: growing germanium monocrystals.
SUBSTANCE: germanium monocrystals are grown from melt on seed crystal with the use of molder filled with melt; molder has holes for removal of excessive melt formed during crystallization. First, crystal is enlarged on rotating seed crystal in radial direction till it gets in contact with molder placed in crucible without melt; then, rotation of crystal is discontinued and crystallization is carried out in axial direction by lowering the temperature till complete hardening of melt; molder is provided with holes in its lower part located at equal distance from one another at radius r satisfying the condition r<K/h, where K= 0.2 cm2; h is height of melt, cm; number of holes, 12-18. Molder may be made in form of round, square or rectangular ferrule. Proposed method makes it possible to obtain germanium crystals of universal shape with no defects in structure, free from mechanical stresses and homogeneous in distribution of admixtures.
EFFECT: increased productivity; reduced technological expenses; increased yield of product.
2 cl, 2 dwg, 2 ex
The technical field
The invention relates to a method of growing single crystals of Germany from the melt.
The level of technology
A method of obtaining single crystals Germany by pulling from the melt by the modified method of Stepanov (Getting shaped single crystals and products by the Stepanov method. P.I. Antonov, Zatulovskaya L.M., Kostygov A.S. and other Leningrad: Nauka, 1981. S-137, 171-175). According to the method of growing single crystals are produced by pre-melting the source material in the crucible and crystallization him on the rotating-crystal seed using immersed in the melt shaper (made in the form of a ring or other shape corresponding to the profile of the grown ingot), which is rigidly attached to the stem of the seed. At the first stage in the process of growth from rotating together with the shaper of the seed single crystal without extrusion is formed of grown crystal that reaches shaper and gets asked lateral surface. The second step is the pulling of the single crystal together with the shaper in the axial direction (i.e., the formation of the ingot height).
The disadvantage of this method is the low yield of single crystals, associated with high levels of thermal stresses in bars, voznikayushie is at the moment of pulling them in the axial direction. Thermal stress lead to a significant inhomogeneity of the refractive index in the single crystals used in infrared optics, reducing the mechanical strength bars - cracking them during machining. The second significant deficiency is a complex technological support raising process: significant (large) mass of melt Germany in excess of the weight of the ingot 3-4 times; the complexity of manufacturing and mounting of the formers on the stem of the seed.
Closest to the proposed method is the method described in the patent No. 1266103 (France, 1961) is a method of producing single crystals of germanium, silicon and intermetallic compounds, namely, that the crystallization of lead from the top down, from a fixed seed, and in the walls of the form (crucible) are very small holes, through which flows the excess of the melt resulting from the increase in volume during solidification. According to the method of the crucible is directly shaper, giving the specified form of the grown ingots. The holes in the crucible is made to remove excessive amount of melt generated due to the difference in the densities of the liquid and solid phases crystallizing material. When the density of the liquid phase, is greater than the solid phase, crystallization is to increase the sample is about 5.3%.
This method of growing single crystals has significant drawbacks. The method is technically difficult to implement on an industrial scale for growing crystals of each given size needs a crucible rather complex configuration. Not specified number of holes, their size - ultimately, this can lead to either leakage of the initial melt, or break the crucible at the time of crystallization. Removing the grown crystal from the crucible is connected with the possibility of mechanical fracture of the crucible and cracking of the crystal. The growing of the crystal forming the main top surface without rotation almost always leads to the appearance of structural defects to polycrystallites and to inhomogeneous distribution of impurities. These deficiencies significantly reduce the yield of products, lead to increased consumption of material (graphite Germany) and make use of the method is virtually impossible on an industrial scale.
The invention
The basis of the invention is the task of improving the yield of products by obtaining single crystals of uniform, defect-free patterns, free from mechanical stresses, a homogeneous distribution of impurities with high productivity and a significant reduction in processing costs
According to the proposed method in the crucible (usually round in shape) asymmetrically placed a shaper in the form of a shell (round or other shape). In the shaper at the junction of the lower part of the shaper to the crucible holes. The radius of the hole (r) must not be greater than the maximum radius (rmax)defined by the formula
where K=0.2 cm2- constant coefficient (Germany); h - melt level in Germany shaper (cm).
The number (N) of apertures in the shaper is 12-18 pieces, the holes are located at equal distances from each other.
The size and number of holes have been evaluated theoretically and tested empirically on the basis of the results of growing single crystals of germanium in the form of a disk with a diameter of 100-300 mm in the shape of a square and rectangle with sides of the cross section of 100-200 mm
The process of growing. In the shaper put a source loading and melt it. The melt remains in the shaper, and does not drain through the holes in the crucible due to the surface tension forces. In the melt is placed rotating the seed crystal and at the first stage, carry out the crystallization in the radial direction with the rotation of the grown crystal before touching his shaper. Next, the ez rotation by lowering the temperature of conduct crystallization in the axial direction before the complete solidification of the total volume of the melt. Excess melt Germany, formed during crystallization, flows through the holes and harden on the bottom of the crucible. When growing crystals Germany all snap - the crucible, the shaper, the heater, the screens are made of graphite.
A brief description and drawings.
The invention is illustrated the accompanying figure 1, which presents the main stages of the process of growing single crystals Germany according to the proposed method. On figa) presents the initial stage of the process: shaper 1, placed in the crucible 2, created the melt 3, whose height is h. In the shaper 1 - in the lower part, primicheva to the bottom of the crucible 2, the holes 4.
On figb) presents the first stage of growing a single crystal of germanium. On the seed crystal 5, rotating at a given angular velocity ω, grown crystal 6. Rotation of the crystal 6 is carried out up until its diameter is close to the diameter shaper 1 (touch crystal shaper). Then the rotation of the crystal 6 is stopped, the upper surface of the melt is completely crystallized.
At the final stage of the process (pigv) crystallization is carried out without rotation in the closed volume of the melt 3. An excessive amount of melt 7, formed during crystallization, flows through Capella the nye 4 holes on the bottom of the crucible 2. The process of draining excess melt 7 will take place until harden the entire volume of the melt 3 in the shaper.
Computational reasoning, confirming the possibility of carrying out the invention
1. Assessment of the required radii of holes
Figure 2 presents the half section, passing through one of the holes in the former, filled with melt Germany with an initial height h. This height remains constant from the moment of melting prior to complete crystallization of the melt surface.
Graphite is not wetted by the melt Germany, and the equilibrium contact angle θpequal 139° (Kostikov V.I., Belov GV Hydrodynamics of porous graphite. M.: metallurgy, 1988. 208 C.). Knowing the value of the surface tension of the melt Germany at the melting temperature of T=C, you can find the value of the maximum radius of the hole rmaxat which the melt height h still held by surface tension and does not escape from the hole. The radius rmaxis found from the equation of Juprana for the height of capillary rise (in our case Nesmachniy - capillary lowering) liquids with density ρW:
where g=980 cm·-2- acceleration of free fall, ρW=5,61 g·cm-2that σW-g=700 DIN· cm-1(Physical quantities. The Handbook. Appalaches, Nagbabasa, Amiradaki and others/ edited Isegoria, Ethmalosa. M.: Energoatomizdat, 1991. 1232 S.).
The module mark in the formula (2) is caused by nonwettability by various graphite melt Germany, in connection with which cosθp<0.
In figure 2, the meniscus of the melt in the hole not shown on the outer and on the inner surface of the shaper, the wall thickness of which is equal to l. This is due to the fact that the germanium crystals grown in conditions where the radial temperature gradient
sent from Central shaper of the crucible to the heater located behind the crucible. Since the magnitude of the surface tension of the melt Germany with increasing temperature decreases, and dσW-g/dt=0,105 Dean·cm-1(Tavadze F.N., Kekua MG, Khantadze D.V., Cerveza YEAR Dependence of the surface tension of liquid germanium and silicon on temperature. In the book: Surface phenomena in melts. Kiev: Naukova Dumka, 1968. S.), the value of the surface tension on the outer, hotter side of the shaper is obviously smaller than that of the more internal cold on the value of
Therefore, if the melt is not charged at the beginning of the hole and penetrates him, he will overcome the surface tension navyhode out of the hole and spilled into the space between the shaper and the crucible walls.
Substituting in the formula (2) constant values, find the value of the maximum radius of the hole rmax:
where the value of K=0.2 cm2. If, for example, the initial level of the melt Germany corresponds to h=4 cm, the value of rmax=0,05 cm, and the diameter of the hole dmax=0,1, see the Minimum possible size of the holes rmincan be found from the condition of equality of the capillary pressure, the tensile strength τ for graphite. According to (Kostikov V.I., Belov GV Hydrodynamics of porous graphite. M.: metallurgy, 1988. 208 C.) value τ is of the order of (1-10) MPa (or 107-108Dean·cm2). Then for σ=1 MPa
as for σ=10 MPa, respectively, rmin≈0.1 ám.
Drilling holes so small radii, first, it is technically difficult to implement, and secondly, to flow the required amount of melt would require a very large number of such holes. Otherwise, the velocity of the melt flow would reach high values and would need to take into account the additional pressure required to overcome viscous friction forces and inertia (the Shepherds B.A., Losenko AV, Furman EL, Khlynov CENTURIES Kinetics of capillary flow of melts in slit and cylindrical channels // Melts. 1988. Vol.2. 4. P.8-13). This in turn led which would increase r min.
Thus, for any feasible radii, holes, smaller than rmaxdefined by (2), their values are known to be greater than rmin. Therefore significant for claims is only the maximum radius of the holes rmaxthat us and sets.
2. Score the required number of holes N
The number of holes N and their relative positioning in the shaper must meet the following requirements:
a) the value of N should be as small as possible. This is due both to the high complexity of drilling large numbers of holes, and a possible decrease in strength shaper;
b) the value of N should be such that the total cross-sectional area of the holes S=Nπr2provided the leakage of the melt in the laminar regime, i.e. with a low enough speed. There should be excluded the increase in pressure due to the forces of viscous friction and inertia, and such hydrodynamic effects as a spray of small droplets at the exit of the holes. For typical values of the parameters characterizing the processes of crystal growth, Germany (time t≈3 hours (104c) from the moment of crystallization of the melt surface in the shaper until crystallization in its entirety; the initial volume of melt Ω0≈1 l (1 3cm3); volume of a melt Ω≈2/3 Ω0, crystallizing in the crucible after complete crystallization of the surface; the radius of the holes r≈rmax≈5·10-2cm, the number of which is N equal to (e.g., twelve), have, with a uniform flow of the desired amount of melt Ω'= Ω(ρW-ρTV)/ρTVthe following is the average flow velocity V of the melt in the hole
Such small values of velocity correspond to the laminar flow of the melt. This is confirmed by the low value of the Reynolds criterion Re, which can be in our case is calculated according to the formula (Zeynalov D.A., Starshinov IV, Titanic L.N., Filippov, M.A. ABOUT the relationship hydrodynamic stability of the melt and the radial impurity heterogeneity in crystals. In the book: Mathematical modeling. Obtaining single crystals and semiconductor structures. M.: Nauka, 1986. P.59-66.):
where ν=102poise is the kinetic viscosity of the melt Germany at the melting temperature. For V=2,5·10-2cm/s, r=0,5·10-2cm, have Re≈0,25. At the same time, the critical values of the Reynolds criterion when fluid flow through the tubes of circular cross section is considered to be the value of Re=2320. Even for holes with radii not 0.5 m is, and 0.1 mm criterion Reynolds (Re≈1,25) remains far below the critical. Therefore, the condition of laminarinase melt flow holes is technically possible sizes in all their quantities N obviously runs;
in) holes in the shaper should be evenly spaced, the distance between adjacent holes shaper must be the same;
g) the distance between adjacent holes in the shaper should not because of the heterogeneity of thermal field to exceed the values in which you may receive at least one enclosed area with the volume of the melt adjacent to the area of the side wall, on which there are no holes.
According to the authors (Calamagrostis A.I. IN kN.: Engineering thermodynamics and fundamentals of heat transfer. M.: metallurgy, 1965. S) ripple temperature for growing crystals Germany amplitude of approximately 1-5K. Experimentally recorded outlet temperature in a typical growth installations detect maximum non-uniform temperature along the wall of the crucible is of the order of 10K. Such radial temperature distortions contribute to the appearance of unbalanced currents in the crucible, resulting in turbulence of the melt and the temperature pulsations in the volume of the crucible. When it can be cold on the order of 5-10K, causing such crystallization,in which near the wall of the shaper will remain closed solid phase (crystal) region of the melt, landlocked in the holes. In this case, a further reduction in temperature and crystallization will lead to pressure on adjacent parts of the wall of the crucible and to its destruction. The number of kinks on izoterma melt in a horizontal plane corresponding to the temperature changes by 5-10K is typically in the range of 20-30K. Therefore, in order to secure the exception of crystallization of closed regions of the melt on the parts of the wall of the former, having no openings, the optimum number of holes N must lie within 12-18 pieces
Embodiments of the inventions
Example 1.
For growing a single crystal germanium in the form of a disc with a diameter of 180 mm and a height of 40 mm in the main graphite crucible having an inner diameter of 220 mm) set graphite shaper in the form of shells round shape with an inner diameter of 180 mm (wall thickness shaper was 5 mm). Based on the height of the crystal melt level) 40 mm, calculate the maximum possible radius of the holes, which in this case was 0.5 mm In the lower part of the shaper, adjacent to the bottom of the crucible, at the same distance from each other has completed 12 holes with a radius of 0.5 mm In the shaper downloaded 5,62 kg annoucing polycrystalline Germany (grade GPP). The installation was evacuated, the heater melt the Yali download then was in the process of growing. The first stage is rotating with a speed of 18 rpm, the seed crystal was lowered into the melt, a heater is required subcooling and razrisovali crystal in the radial direction up to a diameter of 175 mm, Then the rotation of the crystal stopped. The second stage consisted in the regulated lower temperature for 3.5 hours to complete crystallization of the total volume of the melt. The surplus generated during crystallization of the melt flowed through the holes shaper on the bottom of the crucible and also secretaryshall. Weight leaked Germany was 290 grams. After cooling the germanium crystal was removed from the shaper. The grown single crystal had a diameter of 180 mm and height 40 mm; had not expressed mechanical stresses. The single crystal had a satisfactorily uniform in cross-section distribution of impurity - 15%.
Example 2.
For growing a single crystal germanium in the form of a square with a side of 120 mm and a height of 50 mm in the main graphite crucible having an inner diameter of 220 mm) set graphite shaper in the form of a shell square shape with a side (internal) 120 mm (wall thickness shaper was 7 mm). Based on the height of the crystal melt level) 60 mm, calculate the maximum possible radius of the holes, which in this case status is wlel 0,33 mm In the lower part of the shaper, adjacent to the bottom of the crucible, at the same distance from each other has completed 16 holes with a radius of 0.3 mm Holes completed so that the 4 holes in the four corners of a square shaper. In the shaper downloaded 4.8 kg annoucing polycrystalline Germany (grade GPP). The installation was evacuated, the heater melted the download, and then was in the process of growing. At the first stage rotating with a speed of 16 rpm and a seed crystal was lowered into the melt, a heater is required subcooling and razrisovali in the radial direction up to a diameter of 105 mm, Then the rotation of the crystal stopped. The second stage consisted in the regulated temperature reduction within 4 hours to complete crystallization of the total volume of the melt. The surplus generated during crystallization of the melt flowed through the holes shaper on the bottom of the crucible and also secretaryshall. Weight leaked Germany was 250 grams. After cooling the germanium crystal was removed from the shaper. The grown single crystal was in the form of a square with a side of 120 mm and a height of 50 mm; had not expressed mechanical stresses. The single crystal had a satisfactorily uniform in cross-section distribution of impurity - 12%.
Industrial applicability
The application of the method of the POS is olilo successfully to obtain single crystals of germanium (including large) with different shape cross-section, used for manufacturing of optical components (lenses, protective window) infrared technology. The single crystals obtained by the proposed method applied in mass production in industry.
1. A method of growing single crystals of Germany from the melt on a seed crystal using a shaper with internal melt having apertures for removal of formed during crystallization of the excess melt, characterized in that the first rotating the seed crystal carry out razresevanje crystal in the radial direction to his touch shaper placed in the crucible without melt, then the rotation of the crystal stop and carry out the crystallization in the axial direction by lowering the temperature until complete solidification of the total volume of the melt, while using the former, at the junction of the lower part of the crucible perform holes at equal distances from each other, the radius (r) which satises r<K/h, where K=0.2 cm2h - the height of the melt (cm), and the number of holes is 12-18.
2. The method according to po, wherein the shaper is made in the form of the shell is round, square or rectangular.
FIELD: crystal growing.
SUBSTANCE: method comprises growing germanium monocrystals from melt onto seed followed by heat treatment, the latter being effected without removing monocrystals from growing apparatus at temperature within 1140 and 1200 K during 60-100 h, temperature field being radially directed with temperature gradient 3.0 to 12.0 K/cm. Once heat treatment comes to end, monocrystals are cooled to 730-750°C at a rate of at most 60-80 K/h. Monocrystals are characterized by emission scattering at wavelength 10.6 μm not larger than 2.0-3.0% and extinction not higher than 0.02-0.03 cm-1, which is appropriate for use of monocrystals in IR optics.
EFFECT: allowed growth of germanium monocrystals with high optical characteristics.
3 ex
nand low life time of the main charge carriers to the lifetime of minority charge carriers (K =o/n)
FIELD: growing monocrystals of refractory oxides from melts by oriented crystallization; production of sapphire monocrystals corresponding to opto-electronics requirements.
SUBSTANCE: proposed device has vacuum chamber with crucible and molding unit, tungsten heater, shields, rod with seed holder which is provided with crystal raising mechanism mounted outside the chamber, melt make-up system made in form of bin with tube and unit for control of heating and rate of raising the crystal. Device is additionally provided with annealing vacuum chamber mounted above chamber with crucible and molding unit coaxially relative to it and system for synchronization of mass of crystal being grown and consumption of make-up material; annealing vacuum chamber is provided with self-contained heater whose height is equal to or exceeds maximum size of length of crystal obtained; diameter of annealing chamber ranges from 0.6 to 0.9 of diameter of lower chamber; mounted in between chambers is partition with holes for rod with seed holder, crystal being grown and make-up; molding unit is made in form of parallelepiped with parallel through vertical slots which is mounted in crucible at clearance and is secured on crucible walls; height of parallelepiped is equal to 20-30% of crucible height; width of slots is 0.2-0.3 mm at distance between them of 0.2-0.5 mm; in horizontal plane ends of slots are blind. Proposed device makes it possible to eliminate voids lesser than 50 mcm in diameter at obtaining the crystals whose transversal size is lesser than 100 mm at crystallographic orientation of <1010> or <1120>. Power requirements are reduced by 4-6 times. Monocrystals grown with the aid of this device have low internal stresses which is important for further mechanical treatment of crystals.
EFFECT: reduced power requirements; low internal stresses of crystals.
7 cl, 2 dwg
FIELD: production of shaped crystals of refractory compounds such as leucosapphire, ruby, aluminum-yttrium garnet and other by growing from melt according to Stepanoff method.
SUBSTANCE: method comprises steps of evacuating melting chamber and warming heat zone; adding to melting chamber at least one inert gas; providing temperature of heat zone till melting temperature of initial raw material in crucible while filing capillary system of shaper with melt; flashing seed crystal and growing it on end of shaper; drawing crystal; tearing off crystal and cooling it. During those steps applying to melting chamber mixture of inert gases containing, mainly argon and at least helium; setting in melting chamber pressure of mixture that is less than atmospheric pressure and after growing crystal up to its complete section melting off grown part of crystal just till seed and again realizing growing procedure. Then crystal is finally grown. After cooling ready crystal the last may subjected to annealing outside melting chamber for two stages, at first in reducing carbon-containing gas medium including inert gases and then in vacuum.
EFFECT: possibility for producing high optical quality crystals with improved uniformity of optical properties, less loss of yield, lowered cost price of produced crystals.
8 cl, 2 tbl
FIELD: electronic industry; production of profiled crystals from semiconductor materials and other materials used in electronic industry.
SUBSTANCE: proposed method consists in growing profiled crystals from melt by drawing the seed holder and imparting rotation to seed holder and to molding agent with capillary zone for delivery of melt located between inner and outer curvilinear edges of working surface in form of spiral; the following relationship is satisfied: dR/dα≥0, where R and α are radius and angle of polar coordinate system with center at point of intersection of plane in which edges of working surface of molding agent and axes of its rotation lie. Molding agent may be so made that its working surface is located at angle relative to plane of its base. Molding agent may be made at gradual increase of molding surface above base. Proposed method may be used for growing crystals from rubin, sapphire, alumoyttrium garnet, composite eutectics refractory oxides, lithium niobate, molybdates of rare-earth metals and other substances of various forms, hollow parts inclusive in form of cone, sphere, rod (cylinder), ellipsoid at section in form of trochoid or any open curve at homogeneous structure.
EFFECT: possibility of obtaining constant thickness of crystal or thickness changing according to definite law.
5 cl, 10 dwg
FIELD: devices for growing from a melt of polycrystalline layers of silicon used for production of solar sells.
SUBSTANCE: the invention is pertaining to the field of growing from a melt of polycrystalline layers of silicon and may find application in production of solar cells (photoconverters). The substance of the invention: the device includes a crucible for a melt, a heater, a substrate linked with the gear of its relocation and a capillary feeding mechanism. The substrate is made out of a carbon reticular fabric, the heater consists of two sections of heating: a square section, inside which the crucible is mounted, and a right-angled section located above the substrate. At that the cross-section of the heater components is selected so, that the section of heating of the crucible is overheated in respect to the section of heating of the substrate. For a capillary feeding of the melt of silicon from the crucible use harnesses made out of a carbon filament spooled on a tail-end of the feeding mechanism. For replenishment of the level of the melt in the crucible use a vibrofeeder to feed the crushed silicon. The technical result of the invention is an increased productivity of the device and formation of conditions for production of the orientated coarse-crystalline structure of a silicon layer on the substrate naturally open for making of the rear electrical contact.
EFFECT: the invention ensures an increased productivity of the device, production of the orientated coarse-crystalline structures of the silicon layers on the substrates.
1 dwg 1 o
FIELD: devices for continuous grouped growing of the orientated layers of silicon on a carbonic fabric.
SUBSTANCE: the invention is pertaining to the field of growing of polycrystallic layers from a melt of silicon and may be used in production of solar cells (photo-converters) Substance of the invention: the device consist of a crucible for a melt mounted inside a heater, a substrates connected to gears of their relocation and a capillary feeding mechanism. The substrates are made out of a carbonic reticulated fabric, and the capillary feeding mechanism consists of two horizontal sections, located to the left and to the right of the crucible, each of which has a tail swathed by harnesses out of a carbonic thread. The crucible is made with the bottom hollow elongated spout supplied with an independent heater, under the crucible there is a tank for a drain of the crucible residue, the inner surface of which is coated by a layer of a hexagonal boron nitride, and above the crucible a vibrating feeder for feeding the ground silicon is mounted.
EFFECT: the invention ensures growing of polycrystallic layers from a melt of silicon.
1 dwg
FIELD: devices for continuous grouped growing of the orientated layers of silicon on a carbonic fabric.
SUBSTANCE: the invention is pertaining to the field of growing of polycrystallic layers from a melt of silicon and may be used in production of solar cells (photo-converters) Substance of the invention: the device consist of a crucible for a melt mounted inside a heater, a substrates connected to gears of their relocation and a capillary feeding mechanism. The substrates are made out of a carbonic reticulated fabric, and the capillary feeding mechanism consists of two horizontal sections, located to the left and to the right of the crucible, each of which has a tail swathed by harnesses out of a carbonic thread. The crucible is made with the bottom hollow elongated spout supplied with an independent heater, under the crucible there is a tank for a drain of the crucible residue, the inner surface of which is coated by a layer of a hexagonal boron nitride, and above the crucible a vibrating feeder for feeding the ground silicon is mounted.
EFFECT: the invention ensures growing of polycrystallic layers from a melt of silicon.
1 dwg
FIELD: devices for growing from a melt of polycrystalline layers of silicon used for production of solar sells.
SUBSTANCE: the invention is pertaining to the field of growing from a melt of polycrystalline layers of silicon and may find application in production of solar cells (photoconverters). The substance of the invention: the device includes a crucible for a melt, a heater, a substrate linked with the gear of its relocation and a capillary feeding mechanism. The substrate is made out of a carbon reticular fabric, the heater consists of two sections of heating: a square section, inside which the crucible is mounted, and a right-angled section located above the substrate. At that the cross-section of the heater components is selected so, that the section of heating of the crucible is overheated in respect to the section of heating of the substrate. For a capillary feeding of the melt of silicon from the crucible use harnesses made out of a carbon filament spooled on a tail-end of the feeding mechanism. For replenishment of the level of the melt in the crucible use a vibrofeeder to feed the crushed silicon. The technical result of the invention is an increased productivity of the device and formation of conditions for production of the orientated coarse-crystalline structure of a silicon layer on the substrate naturally open for making of the rear electrical contact.
EFFECT: the invention ensures an increased productivity of the device, production of the orientated coarse-crystalline structures of the silicon layers on the substrates.
1 dwg 1 o
FIELD: electronic industry; production of profiled crystals from semiconductor materials and other materials used in electronic industry.
SUBSTANCE: proposed method consists in growing profiled crystals from melt by drawing the seed holder and imparting rotation to seed holder and to molding agent with capillary zone for delivery of melt located between inner and outer curvilinear edges of working surface in form of spiral; the following relationship is satisfied: dR/dα≥0, where R and α are radius and angle of polar coordinate system with center at point of intersection of plane in which edges of working surface of molding agent and axes of its rotation lie. Molding agent may be so made that its working surface is located at angle relative to plane of its base. Molding agent may be made at gradual increase of molding surface above base. Proposed method may be used for growing crystals from rubin, sapphire, alumoyttrium garnet, composite eutectics refractory oxides, lithium niobate, molybdates of rare-earth metals and other substances of various forms, hollow parts inclusive in form of cone, sphere, rod (cylinder), ellipsoid at section in form of trochoid or any open curve at homogeneous structure.
EFFECT: possibility of obtaining constant thickness of crystal or thickness changing according to definite law.
5 cl, 10 dwg
FIELD: production of shaped crystals of refractory compounds such as leucosapphire, ruby, aluminum-yttrium garnet and other by growing from melt according to Stepanoff method.
SUBSTANCE: method comprises steps of evacuating melting chamber and warming heat zone; adding to melting chamber at least one inert gas; providing temperature of heat zone till melting temperature of initial raw material in crucible while filing capillary system of shaper with melt; flashing seed crystal and growing it on end of shaper; drawing crystal; tearing off crystal and cooling it. During those steps applying to melting chamber mixture of inert gases containing, mainly argon and at least helium; setting in melting chamber pressure of mixture that is less than atmospheric pressure and after growing crystal up to its complete section melting off grown part of crystal just till seed and again realizing growing procedure. Then crystal is finally grown. After cooling ready crystal the last may subjected to annealing outside melting chamber for two stages, at first in reducing carbon-containing gas medium including inert gases and then in vacuum.
EFFECT: possibility for producing high optical quality crystals with improved uniformity of optical properties, less loss of yield, lowered cost price of produced crystals.
8 cl, 2 tbl
FIELD: growing monocrystals of refractory oxides from melts by oriented crystallization; production of sapphire monocrystals corresponding to opto-electronics requirements.
SUBSTANCE: proposed device has vacuum chamber with crucible and molding unit, tungsten heater, shields, rod with seed holder which is provided with crystal raising mechanism mounted outside the chamber, melt make-up system made in form of bin with tube and unit for control of heating and rate of raising the crystal. Device is additionally provided with annealing vacuum chamber mounted above chamber with crucible and molding unit coaxially relative to it and system for synchronization of mass of crystal being grown and consumption of make-up material; annealing vacuum chamber is provided with self-contained heater whose height is equal to or exceeds maximum size of length of crystal obtained; diameter of annealing chamber ranges from 0.6 to 0.9 of diameter of lower chamber; mounted in between chambers is partition with holes for rod with seed holder, crystal being grown and make-up; molding unit is made in form of parallelepiped with parallel through vertical slots which is mounted in crucible at clearance and is secured on crucible walls; height of parallelepiped is equal to 20-30% of crucible height; width of slots is 0.2-0.3 mm at distance between them of 0.2-0.5 mm; in horizontal plane ends of slots are blind. Proposed device makes it possible to eliminate voids lesser than 50 mcm in diameter at obtaining the crystals whose transversal size is lesser than 100 mm at crystallographic orientation of <1010> or <1120>. Power requirements are reduced by 4-6 times. Monocrystals grown with the aid of this device have low internal stresses which is important for further mechanical treatment of crystals.
EFFECT: reduced power requirements; low internal stresses of crystals.
7 cl, 2 dwg
FIELD: growing germanium monocrystals.
SUBSTANCE: germanium monocrystals are grown from melt on seed crystal with the use of molder filled with melt; molder has holes for removal of excessive melt formed during crystallization. First, crystal is enlarged on rotating seed crystal in radial direction till it gets in contact with molder placed in crucible without melt; then, rotation of crystal is discontinued and crystallization is carried out in axial direction by lowering the temperature till complete hardening of melt; molder is provided with holes in its lower part located at equal distance from one another at radius r satisfying the condition r<K/h, where K= 0.2 cm2; h is height of melt, cm; number of holes, 12-18. Molder may be made in form of round, square or rectangular ferrule. Proposed method makes it possible to obtain germanium crystals of universal shape with no defects in structure, free from mechanical stresses and homogeneous in distribution of admixtures.
EFFECT: increased productivity; reduced technological expenses; increased yield of product.
2 cl, 2 dwg, 2 ex
FIELD: chemical industry; methods of growing of the rectangular monocrystals of sapphire.
SUBSTANCE: the invention is pertaining to the technology of growing from melts of the monocrystals of sapphire and may be used at production of the volumetric crystals with the crystallographic orientation along the axis <1010> or <1120>. The device contains the vacuum chamber with the installed in it the crucible, the rectangular shaper, the heater assembled out of the lamellas fixed on the current leads, the screens, the rod with the seed-crystal holder and the systems adjusting the hoisting speed of the seed crystal and power of the heater. The crucible, the generatrix of the lamellas and the deflector have the rectangular form, between the bottom of the crucible and the shaper there is the spacing, the altitude of the walls of the shaper exceeds the altitude of the crucible. The wall of the shaper in their upper part are made slit along the ribs and bent off along the slits in the direction of the walls of the chamber, the shaper rests on the upper edge of walls of the crucible by its slit parts. The technical result of the invention consists in the rise of the output of the single crystals up to 60 % due to reaching of integrity of the geometrical shape of the crystal with the crystallographic orientation along the axis <1010> or <1120> and acceleration of the growing process.
EFFECT: the invention ensures the increased output of the suitable single crystals up to 60 % due to reaching the integrity of the geometrical shape of the crystal with the crystallographic orientation along the axis <1010> or <1120> and acceleration of the growing process.
5 cl, 2 dwg
FIELD: crystal growth.
SUBSTANCE: device comprises vacuum chamber with melting pot and molding unit, wolfram heater, shields, rod with the holder for seed provided with a mechanism for lifting crystal and mounted outside of the chamber, and melt make-up system made of a hopper with tube and system for control of heating and rate of crystal lift. The device is additionally provided with roasting vacuum chamber that is mounted above the chamber with melting pot and molding unit coaxially to it and the system for synchronization of mass of the crystal to be grown and the flow rate of the make-up material. The roasting chamber has autonomous heater whose height is equal or exceed the maximum size of the length of the crystal to be grown. The diameter of the roasting chamber is 0.6-0.9 of the diameter of the bottom chamber. The baffle provided with openings for the rod with seed holder is interposed between the chambers.
EFFECT: enhanced quality of crystal.
6 cl, 2 dwg
