Theory of ternary III–V semiconductor phase diagrams

Abstract

Liquidus-solidus phase paradigms of III–V semiconductors are calculated using the Cluster Variation Method and related techniques developed recently. The liquid phase is treated assuming a lattice model. An equilibrium state is derived by minimizing the grand potential ( G ̂ ), keeping the chemical potential fixed. The resulting nonlinear equations are solved using the Natural Iteration Method which has a property that the value of G ̂ always decreases at each iteration cycle. The phase boundary is derived from an intersection of two G ̂ curves; the correct forms of G ̂ values to be used are derived from geometrical considerations. Ternary phase diagrams calculated for InGaAs and InSbAs agree well with previous calculations of Stringfellow and Greene and with experimental data. For ternary cases, a tie line connecting coexisting liquid and solid phases are proved to be orthogonal to the phase boundary curve in the chemical potential diagram.