Structural, electronic and elastic properties of ZnGeN2 and WZ-GaN under different hydrostatic pressures: A first-principle study

The structural, electronic and elastic properties of orthorhombic ZnGeN2 and wurtzite (WZ)-GaN semiconductors have been studied under different pressures using first-principle density functional theory (DFT) calculations. The lattice constants (a, b and c) and energy bandgaps (E-g) have been calculated under ambient condition. The elastic properties such as elastic stiffness constants (C-ij), shear modulus (G), bulk modulus (B), Young modulus (gamma), B/G ratio and Poisson ratio (v) have been studied at 50, 100, 110, 120, 150, 160, 180 and 190 GPa pressures for the first time as well as at 0 GPa. The calculated values of C-ij show that the ZnGeN2 and GaN are stable up to 180 and 150 GPa, respectively, and afterwards phase changes and become unstable. The band structure of ZnGeN2 reveals direct band gap behavior up to 100 GPa and becomes indirect band gap at 110 GPa. However, GaN is direct band gap up to 150 GPa and becomes indirect at 160 GPa. Comparing the results of both semiconductors, it is observed that ZnGeN2 is similar to WZ-GaN up to 100 GPa in all respect and can be used in many applications in place of WZ-GaN. The calculated values of all parameters are in reasonable agreement with the known values.