我国首次空间生长GaAs单晶实验的结果分析

在空间微重力环境中,用重熔再结晶法从悬浮熔体生长了掺杂Te-GsAs单晶,晶体从中间断开表明长悬浮熔体的不稳定性,晶体中部未见杂质条纹说明浮力对流已消失,而外层有杂质条纹表明存在Marangoni对流,晶体中杂质含量减少和宏观分布不均匀,是短熔区杂质分凝机制控制和杂质Te从熔体挥发的结果,晶体中的高位错缺陷是快速生长和退火时产生的热应力以及界面籽晶侧的空位团崩塌造成的。 关键词：

ANALYSIS OF RESULTS OF CHINESE FIRST EXPERIMENT ON GaAs SINGLE CRYSTAL GROWTH IN SPACE

By the method of remelting and recrystalization, the GaAs single crystal doped with Te grew from the floating melt in microgravity environment in space. The GaAs single crystal broke in the middle, showing that the long floating melt was not stable. No impurity striations were found in the middle part of the crystal, which indicated that buoyancy-driven convec-ion disappeared, but they were observed on he outer layer of the crystal, showing that there existed Marangoni convection. The control of segregation mechanism of impurities in the short melting zone and the volatilization of Te impurity from the melt resulted in the decrease of impurity contents and nonuniform macroscopic distribution of impurities in the crystal. The dislocation defect in the crystal was due to the thermal stress caused during rapid growth and the collapse of vacancy clusters at the side of interface seed crystal.