METHOD OF CLEANING MELT SURFACE WHEN GROWING GERMANIUM MONOCRYSTALS Russian patent published in 2018 - IPC C30B15/00 C30B29/08 C30B15/22 C30B15/36 B22D43/00 F27D3/15 

FIELD: metallurgy.

SUBSTANCE: essence of the invention consists in extraction of slags (oxide films) from the melt surface, and from crucible walls below the level of germanium melt in the crucible. The method consists in collecting the most part of all available oxide films on the melt surface and below melt level in the zone where it adjoins the crucible by sticking thereof to a preliminarily grown crystal. The result of efficient melt cleaning is achieved by adjusting the rotation speed of the crucible, crystal, the crucible position in a heat unit, as well as consumption of working gas (argon), wherein maximum high concentration of slag on the melt surface of crystal growth zone is achieved, and it facilitates their extraction on the preliminarily grown crystal. The preliminarily grown crystal is subjected to 2-5 cycles of sharp pulling with separation of the preliminary crystal from melt and then its subsequent complete immersion into the melt, which provides separation of slag impurities from the crucible below the melt level with subsequent floating thereof on the melt surface. Subsequent drawing up the preliminary crystal in each cycle provides collection of oxide films from the melt surface onto crystallisable surface of the ingot.

EFFECT: yield of monocrystals with significantly lower dislocation density, reduced risk of twinning and polycrystallisation of the ingot during the growing process and reduced average time of the growth plant working cycle.

2 cl, 2 ex