Thermodynamic analysis of Ga xB 1− xN grown by MOVPE

Abstract

A thermodynamic model was applied to predict the GaBN MOVPE growth such as the equilibrium partial pressures, vapor–solid distribution relation, and growth efficiency. The delta-lattice-parameter (DLP) method was employed to determine the activities of the binary compounds. The large structural dissimilarity between BN and GaN results in a high interaction parameter of 70 730 cal/mol, indicating that GaBN deviates greatly from an ideal solid solution. A V/III ratio>100 is required for the growth of GaBN at 1000°C to avoid Ga droplets on the growth front. The growth of GaBN is controlled by the much higher Ga partial pressure than that of B over the alloy. The unstable regions in which inhomogeneous compositions are formed exist in the GaBN alloy based on the vapor–solid distribution relation. The predicted growth behavior of GaBN agrees well with the experimental data.