Vapor Transport Thermodynamics of GaP-Cl2-H2 System in an Open Tube

Abstract
In order to define the most suitable conditions for the transport of gallium-phosphide the composition of the gas phase is calculated for various temperatures and chlorine-to-hydrogen mole ratios in an open tube process. A transport rate equation base on thermodynamic considerations has been developed. It is shown that the principal components are HCl, GaCl3, GaCl, and P4 at low temperature, and HCl, GaCl, and P2 at high temperature, in addition to H2 for a Cl2/H2 mole ratio of 1×10-2. The hypothetical partial pressure of gallium-phosphide, from which the deposition rate of GaP may be conveniently estimated, is calculated.