Atomistic calculations of defects in ZnGeP2

Abstract

Atomistic calculations are performed to study defect energetics in ZnGeP2 where two- and three-body interatomic potentials are used to simulate the perfect lattice. Formation energies for native ionic defects and binding energies for some of the electronic defect complexes are calculated. The dominance of antisite defect pairs, ZnGe+GeZn, is predicted in the lattice. However, the defects controlling the spectroscopic properties would seem to be associated with vacancies. For the EPR-active acceptor center, the hole is found to be localized near the zinc vacancy rather than near the zinc antisite (ZnGe). The calculated results suggest that the reported Hall effect and the photoluminescence data are compatible with the existence of two acceptors in the lattice (in a three level model) where one is significantly shallower, experimentally by 0.27 eV, in reasonable agreement with the calculated difference of 0.37 eV.