Numerical modelling and analysis of binary compound semiconductor growth under microgravity conditions

We investigate the possibility of growing a uniform binary compound crystal in space numerically, employing a new crystal growth technique called the Graded Solute Concentration method. We develop a numerical calculation meth od of the growth of binary crystals. The calculation method is applied to t he crystal growth of an InAs-GaAs binary semiconductor by the Bridgman and zone methods and the effect of buoyancy convection induced under microgravi ty conditions on the crystal growth process is investigated. We find that t he concentration field is disturbed and, as a result, the solution-crystal interface is deformed by buoyancy convection in the case of the Bridgman me thod even when the gravitational acceleration is as low as 10(-6)g, which i s supposed to be the gravity level in the International Space Station. We a lso find that buoyancy convection is reduced in the case of the zone method and therefore uniform binary crystals may be grown by the zone method. (C) 2001 Elsevier Science B.V. All rights reserved.