FOREIGN ATOM THERMODYNAMICS IN LIQUID GALLIUM-ARSENIDE

Thermodynamic equilibrium in gallium arsenide crystal growth systems w ith the components Ga-As-C-B-N-Si-O has been analysed by using a Gibbs energy minimisation computer package. Emphasis is placed on graphical representations to describe the behaviour of C, B, Si and O in the cr ystal growth melt at 1513 K. The various experimentally observed corre lations between solute elements in the liquid and the encapsulant are rationalised. Additionally, guidance is provided for improvements in t he design of crystal growth operations. Instead of relying on the curr ent procedure of maintaining purity control on the input materials and standardised operating conditions, it is suggested that the flow of w et CO or H-2/CO2 input gas flow mixtures be used to fix C and O activi ties and, thereby, reduce the thermodynamic degrees of freedom of the system to zero. (C) 1998 Elsevier Science B.V. All rights reserved.