Calculated optical properties of GaX (X=P, As, Sb) under hydrostatic pressure

Abstract

The hydrostatic pressure dependence of the principal energy gaps and of the optical properties of GaX (X = P, As and Sb) has been calculated using the full potential-linearized augmented plane wave (FP-LAPW) method. The generalized gradient approximation (GGA) for the exchange and correlation potential is applied. Also, we have used the Engel-Vosko GGA formalism, which optimizes the corresponding potential for band-structure and the optical properties calculations. Structural properties such as equilibrium lattice constants, the bulk modulus, and its pressure derivatives were calculated for GaP, GaAs, and GaSb in the zinc-blende structure (ZB). We have found that the results of the structural properties calculations are in agreement with those of ab initio and experimental data. In general, the pressure dependence of the principal energy gaps is compared to other values. The same is for the pressure coefficient. However, for the same structure, the comparison of our results with those of experimental and theoretical calculations shows good agreement. On the other hand, the effect of the applied pressure is clearly seen in the optical properties especially near the energy transition regions.