Thermodynamic considerations in the synthesis and crystal growth of GaSb

Abstract

We use a newly developed optimization algorithm, the “sticky trust region technique”, for Gibbs energy minimization to determine the gaseous species and liquid and solid phases present during the synthesis and crystal growth of GaSb. The growth system involves almost thirty species comprising a gaseous phase and nine condensed species. We model the system as a function of temperature, oxygen and hydrogen pressure in the presence of an SiO 2 crucible. Ga 2O 3 is identified as the most stable contaminant compound and is seen as a phase that floats on the liquid melt during growth. This oxide often prevents the growth of high quality crystals. We show the effects on its thickness of increasing the ambient hydrogen concentration and determine that the SiO 2 crucible is not an important source of the contaminant oxygen except at high temperatures. The Gibbs energy minimization method combined with the newly-developed optimization algorithm is shown to be an efficient tool for evaluating the problems of cystal growth, materials synthesis and purification.