Patent ID: 7972439

Claim:
A method for producing single crystals by growing from melt, which comprises fusing a starting material and pulling a single crystal by crystallization of a melt on a seed crystal with controlled removal of crystallization heat and with using independent heat sources which constitute thermal zones, wherein the independent heat sources constitute two equal-sized coaxially arranged thermal zones which make up a united thermal area for the melt and the single crystal being grown, said zones being separated by the melt surface, fusing of the starting material being carried out in two stages: first by heating the upper thermal zone with supplying to an upper heater 30-50% of power required for obtaining the melt, until in the upper thermal zone maximum temperature is reached, which secures stable state of the solid phase of the seed crystal; then the remaining power is supplied to the lower thermal zone to a lower heater with maintaining constant temperature of the upper thermal zone till complete melting of a charge; the process of the single crystal enlargement and growing is conducted with controlled lowering of temperature in the upper thermal zone, the amount of power supplied to the lower thermal zone being preserved constant.