Numerical analysis of InGaAs crystal growth of a uniform composition under microgravity conditions

We developed a calculation method of 1D crystal growth of InAs-GaAs binary semiconductors and investigated the effect of the cooling rate an the temperature gradient on the crystal growth process under zero gravity conditions. We found that crystal of uniform compositions can be grown by the 1D growth method with a nonuniform concentration gradient in the solution if the growth rate is 3-5 mm/h. Furthermore, we investigated the occurrence of constitutional supercooling and found that the degree of supercooling can be reduced if the temperature gradient ins larger than 30 K/cm. We also developed a calculation method of 2D crystal growth of InAs-GaAs binary semiconductors, in which buoyancy convection induced by both temperature and concentration differences is taken into account, and investigated the effect of residual gravity and the inclination of the crucible on the crystal growth process. We found that convection is induced even under 10-6 g conditions and that the crystals-solution interface is deformed by the convection. Convection is reduced and diffusion conditions can almost be realized if the growth direction is opposite to residual gravity. Convection becomes quite strong when the growth direction is perpendicular to gravity. The possibility of growing uniform crystals when the growth direction is inclined against the gravitational direction is discussed.