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.