| 摘要 |
PURPOSE:To form GaAs single crystals free from concn. fluctuation in crystal growing direction by performing the crystal growth from the melt of mixture which is composed of Ga and As at a prescribed proportion and added with oxygen. CONSTITUTION:A raw material mixture in which (C) oxygen of 10<7>-10<-4> molar ratio based on GaAs is added to the mixture of (A) 0.930593pts.wt. Ga and (B) 1.049392pts.wt. As is used and the crystal growth is performed with the horizontal Bridgman technique. Namely, a boat (made of boron nitride) 3 incorporated with seed crystal 2 of GaAs and the above-mentioned raw material mixture 4 is arranged on one side of a reaction tube 1 and on the one side, powdery As 7 is arranged on the other side of the reaction tube 1 separated with a diffusion barrier. Then, after the reaction tube 1 is heated at >=1,250 deg.C tomake the melt of the mixture 4 and the powdery As 7 is heated at 610 deg.C to generate the As vapor 8, the temp. of the melt is lowered to 1,050-1,200 deg.C from the part contacted with the seed crystal 2 to grow the semiinsulating GaAs single crystal slowly (at about 3mm./h).
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