Theoretical study of the formation of deformation twins in GaAs crystals grown by the vertical gradient freeze method

Abstract

The objective of this paper is to predict the twin formation in the Gallium Arsenide (GaAs) crystals grown by vertical gradient freeze (VGF) method at different growth parameters. The deformation twins are formed in the GaAs crystal during its growth processes from the melt. The thermal stresses generated by the temperature profile during the crystal growth can be the primary cause of deformation twin formation. Temperature gradients are depend on the geometrical and physical crystal growth parameters, such as crystal diameter and imposed temperature gradients on the surface of the solidifying crystal in VGF. A quantitative thermal stress model is developed here for predicting the twin formation in GaAs grown by VGF at different growth parameters. This investigation is expected to further the understanding of twin formation. This understanding will provide valuable information to crystal growers to study the influence of growth parameters on twin formation for growing low defect GaAs crystal. (C) 2001 Kluwer Academic Publishers.