Calculation of ternary and quaternary III–V phase diagrams

Abstract

The models used to calculate binary and ternary III–V phase diagrams are reviewed. The simple solution model with Ω=a−bT is found to satisfactorily describe the liquid phase and the solid phase is adequately described using the regular solution model. The DLP (delta lattice parameter) model of the solid, based on the concept that the bonding in alloys is determined largely by the energy of the electrons, is found to be capable of predicting accurately the magnitudes of the solid interaction parameters knowing only the lattice parameters of the pure III–V compounds. The simple solution model with Ω=a−bT for the liquid and DLP model for the solid is then used in the calculation of the quaternary III–V phase diagrams. One outcome of the calculation is the establishment of a condition which can be used to check the consistency of the parameters ΔHF, TF and Ω1 of the four solid III–V compounds bounding the solid phase field, against the solution model. The agreement of the calculated quaternary results with experiment in the GaxIn1−xAsyP1−y system is satisfactory. In the AlxGa1−xPyAs1−y system, the consistency condition is not satisfied, and thus the calculation cannot agree with previous ternary calculations for the (Al,Ga)As, (Al,Ga)P and Ga(As,P) systems simultaneously. Parameters were chosen so that good agreement is established with all except the (Al,Ga)P ternary.