PURPOSE: To manufacture the title single crystal free from an oxide layer, twins, subgrain boundaries, etc. by melting mixed salt of NaCl and KCl together with constituents for a III-V group compound semiconductor single crystal and growing a single crystal.
CONSTITUTION: Starting materials for a III-V group compound and NaCl-KCl liq. capsule mixed salt 2 are put into quartz crucible 3 and melted by induction-heating carbon heater 4 with high frequency coil 5. Seed crystal 12 is then contacted to the surface of starting material melt 1 through salt 2, well fitted, and pulled at an appropriate rate with rotating to grow single crystal 13. Crystal of salt 2 attaches to the surface of crystal 13 and forms mixed salt thick film 14. Accordingly, surface oxidation, volatilization and evaporation of crystal 13 are controlled. Since a thermal strain immediately after crystallization is relieved under the mild temp. distribution in salt 2, twins and subgrain boundaries are not formed.