FIELD: chemistry.
SUBSTANCE: invention can be used in growing monocrystals from melt by zone melting by crucible-free method. In the housing of growth chamber 2 with movable lower 8 and upper 12 rods, seed crystal 7 is placed vertically, loading in the form of feed rod 11 or a mixture in the form of granules, a multi-section background heater and AHF heater 9 in a sealed housing having a diameter D, height H, equipped with at least two heating elements in its upper and lower parts. Upper 3 and lower 4 sections of the background heater are located with gap 5 for monitoring the crystallisation process through window 1. Upper 3 section of the background heater is equipped with at least three uniformly arranged current leads fixed in the cover of growth chamber 2, connected to each other outside it by means of an electrically insulating ring. Possibility of movement of current leads in vertical direction is provided by a movement mechanism made in the form of a screw, the lower part of which is inserted into a pocket located in the cover of growth chamber 2. AHF heater 9 is arranged along the axis of growth chamber 2 and can be displaced vertically by means of ceramic support tubes arranged vertically at angle of 120 degrees relative to each other and secured by their lower parts in the bottom part of growth chamber 2 by means of supports. Inside ceramic support tubes, there passed are supply electrodes connected to heating elements of AHF heater 9. Feed rod 11 or charge is heated to melting temperature at contact with upper surface of AHF heater 9, as a result of which a molten zone is formed, which is feed melt 10, and molten zone 6 is formed in the gap between the lower surface of AHF heater 9 and seed crystal 7, from which a monocrystal is growing, held by surface tension forces for a time sufficient for establishing an equilibrium temperature of the melt before its crystallisation, to control the shape of melted zone 6 and to create the required temperature gradient at the phase boundaries together with the multi-section background heater. AHF heater 9 can be equipped with through vertical hole with diameter d or made without it. If AHF heater 9 has a hole, then it is filled with feed melt 10 to produce a drop flowing into the gap between the bottom surface of AHF heater 9 and seed crystal 7. In this case, the diameter D1 of seed crystal 7 and the shape of the meniscus of feed melt 10 in this gap are selected based on the generalized dimensionless parameter 
, where α is the value of its capillary constant. If 1.6 < A < 2.0, then providing the convex shape of the meniscus of feed melt 10 and completely filling the said gap, diameter D1 of seed crystal 7 is selected to be larger than the diameter of the AHF-heater D by 2–14 mm, and drawing of the monocrystal is started after holding melted zone 6. At 1 < A < 1.6, seed crystal 7 is brought to the lower surface of the AHF heater at distance of 2α⋅d1/3, diameter D1 of seed crystal 7 is selected less than diameter of AHF heater 9 in accordance with the ratio D1 = 2.2⋅α, providing a convex shape of the meniscus of feed melt 10, and drawing the monocrystal is started immediately after filling the gap between the lower surface of AHF heater 9 and seed crystal 7 with the feed melt. At A>2, the diameter of seed crystal 7 does not matter, and drawing of the monocrystal is started after holding melted zone 6. If AHF heater 9 is made without a hole, then seed crystal 7 is used, the diameter D1 of which is close to the diameter D of AHF heater 9, in accordance with the relationship D1 = D - 2⋅2.2α. In this case, in the cover and the bottom part of the housing of AHF heater 9, an inflow is made in the form of a circular recess with depth of 1–2 mm and a diameter which is 5–15 mm greater than the diameter of feed rod 11 or seed crystal 7, and additionally milling grooves in radial direction from inflow to edge of housing with width of 0.5–1 mm and depth of 0.2–0.3 mm, performing the function of capillaries for uniform supply of feed melt 10 along the whole circumference of the housing of AHF heater 9, flowing to its bottom and filling the gap between the lower surface of AHF heater 9 and seed crystal 7.
EFFECT: invention makes it possible to increase quality of grown monocrystals and efficiency of their production due to creation of melted zone 6 before crystallisation, having required height uniformly along the whole section of seed crystal 7, and provision of required thermal conditions at phase boundary.
3 cl, 6 dwg, 8 ex
