Structural phase transition and high-pressure elastic behavior of III-V semiconductors.

Abstract

We have expressed the Gibbs free energy for III-V compound semiconductors as a function of pressure and charge transfer through three-body interactions. The lattice energy in it has been represented by a three-body potential consisting of the long-range Coulomb and three-body interactions, and the short-range van der Waals attraction and overlap repulsion, effective up to the second-neighbor ions. We have depicted the phase diagrams and found that the abrupt volume collapses at the phase-transition pressures agree fairly well with the observed data. The phase-transition pressures (17.0, 4.0, 17.1, 18.0, 1.0, and 11.0 GPa) obtained by us are in close agreement with the experimental data (18.5, 6.7, 22.0, 8.4, 2.2, and 10.8 GPa) for almost all the semiconductors (GaAs, GaSb, GaP, InAs, InSb, and InP) under consideration. The elastic stiffness constants (${C}_{11}$) have been found to increase with pressure while the shear moduli (${C}_{11}$-${C}_{12}$)/2 and ${C}_{44}$ decrease with it, and this feature is consistent with the experimental observations.