Device for growing crystals in the form of rods and tubes from the melt
(57) Abstract:The invention relates to techniques for growing shaped crystal pulling from the melt with rotation using formers and can be used to produce monocrystalline tubes and rods with periodically varying impurity content along the length of the crystal. The inventive device includes a crucible 1 with a dividing partition 2 dividing the melt 3 and 4 with different content of impurities, additional shaper 5, secured in one of the tanks crucible with the melt 3), the screen 6 with an opening 7 and is fixed on the screen shaper 8. The device allows you to receive periodic patterns with the changing ratio of the heights of layers of different composition in the process of growing the crystal by means of vertical and horizontal movement in the plane of the screen for more shaper by raising, lowering or rotating the crucible. In the grown crystal can be obtained variables periodic structure, the ratio of the height of the layers of different composition andi/biin which changes in the range (-a)/(a+a) ai/bi(+a)/(-a). 2 Il. Izobreteniyem of formers and can be used to produce monocrystalline tubes and rods with periodically varying impurity content along the length of the crystal.The closest technical solution is a device for receiving a tubular crystals with periodically varying along the length of the structure  . The device contains two or more crucibles for melts of different compositions, the shaper mounted on the screen above the crucible. The working surface of the shaper made in the form of isolated from other areas located around the circumference, each of the sections has a capillary channel to the corresponding melt composition and the seed crystal mounted in structurally connected with the mechanism of rotation and displacement. Using this device were obtained pipe with a layered structure LiF-LiF: MgF2 .However, this device does not allow to obtain crystals with various and variable duty cycle regular patterns with a given frequency, i.e. with a constant and/or variable thickness ratio of layers of different compositions.The technical result achieved by the present invention is to obtain crystals with a periodic distribution of impurity concentration, determined according to a given program with constant or variable ratio of the thickness of the various layers is monocrystalline rods and tubes from the melt with a layered distribution of impurities, including structurally connected with the mechanism of its movement and rotation, a crucible mounted for movement, and the shaper mounted on the screen, the crucible is made with a dividing partition for melts with different content of impurities and is mounted for rotation in one of the tanks of the crucible is rigidly fixed additional shaper, and the screen is made the hole for the free movement of additional shaper. In the crucible, separated by a partition, are the melts with different content of impurities. On the screen is the former, power is provided from one of the tanks, and also made a special hole that allows you to perform manipulations on the vertical and horizontal movement in the plane of the screen, shaper, rigidly fixed to the other tank of the crucible. All moving additional shaper is done using the vertical movement and rotation of the crucible, while fixed on the screen shaper remains stationary. The crystal growth is carried out layer by layer by simultaneously rotating and pulling ZAT is ovately in a specific mode. The device allows to achieve the same periodic structure as by means of vertical movement of the crucible, and the rotation of the crucible within 90o. Vertical movement of the crucible h, limited by the range of allowable values in the range 0 h hmwhere hmthe meniscus height, allows you to change the height of the working edges additional shaper relative to the working surface level shaper associated with the screen, allowing the meniscus height on the secondary shaper will vary in the same proportion, which in turn determines the width of the corresponding layer in a periodic structure. The variation of the position of the crucible lifting and lowering allows you to control the width of the layer of one of the compositions of the periodic structure. A similar result in periodic structures and changes in the ratio of layers of these structures directly in the process of growing crystal can be achieved by rotating the crucible about its axis within 90o. When the rotation of the crucible additional shaper moves freely in the hole. The height of the crystallized layer of the melt for one revolution of structurally is the sum of savannaha a layer of rolling shaper is determined by the ratio a = ()/2, where v is the velocity of extrusion, mm/min, the rotation frequency, Rev/main, the angle at which offset additional shaper. In this case, if the additional rotation of the former coincides with the direction of rotation of structurally, the values lie in the range of 0 90in the case of rotation of the additional shaper against the direction of rotation of structurally changes in the range -900. Accordingly, the height of the layer b is determined by the same ratio, but the sign in front of each case is reversed.In Fig. 1 presents a General view of the apparatus for growing crystals, this shows the operation of the device at the time of lowering of the crucible, resulting in a change in the thickness of one of the components of the periodic structure. In Fig. 2 presents a view of the device at the moment of changing the ratio of components of the periodic structure in the rotation of the crucible.The device includes a crucible 1 with a dividing partition 2 dividing the melt 3 and 4 with different content of impurities, additional shaper 5, secured in one of the tanks crucible with the melt 3), the screen 6 with an opening 7 and is fixed on the screen vormoor the melt 3, 4 with different dopant content. The persecution of the crystal is carried out on the working surfaces of the formers 5 and 8 are at the same level and in diametrically opposite positions, through which enter the melt 3 and 4, respectively (Fig. 1). During subsequent rotation of the seed crystal and its simultaneous pulling is carried out layer-by-layer growth of a crystal, and this position of the formers allows to obtain monocrystalline pipe with a periodic structure in which the thickness of layers of different composition (assuming equality of the areas of the working surfaces of the formers) are equal.Getting regular structures with the changing ratio of layers of different compositions in the crystal growth process may be done in two ways. The first method is the vertical movement of the additional shaper 5 using the raising and lowering of the crucible (Fig. 1). The level of working shaper edges 8 remains constant, while the level of working shaper edges 5 depends on the height of the raising or lowering of the crucible. The width of the periodically repeating regions with the composition of the melt 3 is increased in the case of SDA is th same dependencies. Raising the crucible leads to the opposite effect.The second use case allows the device to achieve the same periodic structure. Hole 7 provides a free horizontal movement of the shaper 5 around the circumference in the plane of the screen when you rotate the crucible (Fig. 2). The rotation of the crucible 1 at an angle in the direction of rotation of structurally leads the shaper 5 in the movement of the hole 7, the smaller the angle between the formers 5 and 8 are changed to values. When the rotation of the crucible against the direction of rotation of structurally the reverse effect. Thus in the growing crystal can be obtained variables periodic structure, the ratio of the height of the layers of ai/bithat can vary (-)/(+) ai/bi(+)/(-). Doped and undoped layers in these crystals represent the helix angle of the lifting screw line = arctan(/2R) , where R is the distance from the axis of rotation of structurally to the centers of the formers (in case of equal distance of the location of the formers from the axis of rotation of structurally).Example 1. Grown tubes sapphire diameter of 25 mm, wall thickness which was rawnie impurities did not exceed 10-4weight. %), another molten sapphire with the addition of titanium (0,5 weight. %). The thickness of the partition walls of the crucible was 3 mm, the diameters used in these experiments, the formers were equal to 4 mm, and the distance between them is ~ 21 mm Persecution was carried out on a rotating seed. The growing crystal was carried out with the speed of extrusion of 0.4 mm/min and rotational speed of structurally 2 rpm Additional shaper is fixed in the tank with alloyed molten. At diametrically opposite placement of the formers, the thickness of the layers of the periodic structure was equal to 100 μm (Fig. 2, a). Then the crucible was started to rotate at the rotation speed of structurally, i.e., ~ 2 rpm During the rotation of the crucible in the direction of rotation of structurally the ratio of doped and undoped layers were changed depending on the angle of movement of the crucible (Fig. 2, b). So, when you rotate the crucible at 45othe relationship between the layers was 75 μm/125 μm, and in the end position of the formers, i.e., when the rotation of the crucible 90othe ratio of the layers was equal to 50 μm/150 μm. Rotating the crucible from this position in the opposite direction, i.e. against the direction of rotation of the La>othe ratio of the layers was changed to the value of 150 μm/50 μm. Thus, we have obtained single-crystal tube with periodic structures in which the change in the ratio between layers with different concentration was controlled during crystal pulling.Example 2. Grown sapphire tube outer diameter of 23 mm and an inner diameter of 9 mm, length 150 mm, wall thickness which was equal to 6 mm In one part of the molybdenum crucible was unalloyed melt sapphire (impurity content of not more than 10-4weight. %), and another was placed melt sapphire with the addition of titanium up to 0.5 weight. %. The thickness of the partition walls of the crucible ~ 3 mm, the diameters of the formers were equal to 6 mm, the distance between them is 15 mm. Conditions and modes of persecution and pulling of the crystal similar to that shown in example 1. Additional shaper was enshrined in the tank with alloyed molten. Managing change in the ratio of the layers was carried out by the lifting and lowering of the crucible in the range of 50 microns. In the initial position of the formers (Fig. 2, and in modes pulling speed of 0.4 mm/min and rotation speed of 2 rpm thickness of the doped and undoped periodic structures were changed to the values respectively of 75 μm/125 μm and 50 μm/150 μm. The height of the lifting and lowering of the crucible was changed with a speed of 0.4 mm/min After lifting 50 μm crucible with this speed was down to 100 microns, i.e., to a value of -50 μm initial position of the crucible. The result has also been obtained monocrystalline tube with periodic structures in which the change in the thickness of layers with different concentration during crystal pulling ranged from 1/3 to 3/1.Compared with the prototype of the proposed solution allows to obtain crystals with controlled periodic structures, the ratio of the layer thicknesses which may vary in the process of growing the crystal.LITERATURE
1. Yu, noses, P. I. Antonov, and S. P. Nikanorov. The method of obtaining single-crystal tubes, and a device for its implementation. USSR author's certificate N 1306173, C 30 15/34,1985.2. Antonov P. I. , noses, Y. G. , Nikanorov S. P. Formation of crystals of form element melt. - Izv. An SSSR, ser. physical , 1985, I. 49, S. 2295-2297.3. C. N. Kurlov, S. C. Belenko. Receive periodic structures in shaped sapphire crystals, activated ions Ti3+, Cr3+. - Neorg. materials, such as 34, 1998, No. 6, S. 697-699.
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.
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
FIELD: technological process.
SUBSTANCE: invention pertains to growth of monocrystalline silicon layers from a molten mass, and can be used in making solar cells (photoconverters). The device consists of a crucible for melting, a heater, consisting of two heating sections: a square one, the inside of which is fitted with a crucible, and a rectangular one, put over a substrate, a substrate, linked to its displacement mechanism, capillary feeder, bundles of carbon fibres, wound on the tail of the feeder, and a vibrating feeder for supplying crushed silicon. The substrate used is a carbon foil, covered by pyrographite layers. The capillary feeder has an opening for putting in the substrate, and the rectangular heating section is symmetrical about the substrate and has vertical incisions for letting in the substrate.
EFFECT: increased output of the device due to growth of thin silicon layers at the same time on both surfaces of the substrate, due to reduction of the specific consumption of initial silicon due to that, the substrate does not get soaked in the molten mass.
1 ex, 2 dwg
FIELD: metallurgy, crystal growth.
SUBSTANCE: invention concerns field of receiving profiled crystals of refrectory compounds, for instance, leucosapphire, ruby, yttrium aluminum garnet and others, growth from melt by method of Stepanov. Facility contains pot with installed in it form-builder with vertical capillary channels, at that it is outfitted by nozzle, fixed on bottom end of form-builder, enveloping it with forming of closed cavity, communicating to pot chamber by means of holes, implemented in nozzle. Nozzle can be fixed on bottom end of form-builder as with firm adherence to its side walls, as with formation of open between side walls of nozzle and form-builder. In nozzle chamber which is lower butt end of form-builder can be located filler with ability of passing of melt to the capillary channels. Filler can be implemented in the form of rods, or plates, or wires and located in chamber of nozzle as several layers.
EFFECT: receiving of crystals of higher quality, increasing of product yield and decreasing of cost price of receiving crystals.
11 cl, 4 dwg