THE STRUCTURAL AND ELECTRONIC PROPERTIES OF GAN UNDER HIGH PRESSURE

Abstract

The structural phase transformations of GaN under high-pressure are studied using the full-potential linearized augmented plane wave (FP-LAPW) approaches within the density functional formalism (DFT) in the local density approximation (LDA) and the generalized gradient approximation (GGA). We have calculated the ground-state energy, the lattice constant, the bulk modulus, its pressure derivative, and the electronic structure of the wurtzite (WZ), zinc-blende (ZB) and rocksalt (RS) phases of GaN. The GGA results of the critical pressure of the WZ→ZB and WZ→RS transitions present small but non negligible variations with respect to the LDA results. The RS-GaN is predicted to be an indirect band gap semiconductor, with a band gap of 1.68 eV.