Effects of ampoule rotation on vertical zone-melting crystal growth: steady rotation versus accelerated crucible rotation technique (ACRT)

Computer simulation is performed to illustrate the significance of ampoule rotation on the flows, interface shapes, and the growth rate in vertical zo ne-melting (VZM) crystal growth. For the growth of a 2 cm GaAs crystal in a quartz ampoule, simulation results show that even low-speed ampoule rotati on can significantly affect the flows and further the growth interface. The concave growth front due to buoyancy convection can be inverted easily to a convex one by steady ampoule rotation. The accelerated crucible rotation technique (ACRT) also has a similar effect on the growth interface, but les s effective. In addition, severe periodic growth and remelting is induced b y ACRT, and it is enhanced significantly by natural convection. (C) 1999 El sevier Science B.V. All rights reserved.