Atomistic calculations were used to study defect energies, with 2-body and 3-body interatomic potentials being used to simulate a perfect lattice. The formation energies for native ionic defects, and the binding energies for some of the electronic defect complexes, were calculated. A predominance of antisite defect pairs, ZnGe+GeZn, was predicted to exist within the lattice. However, the defects which controlled the spectroscopic properties seemed to be associated with vacancies. In the case of the electron paramagnetic resonance-active acceptor center, the hole was found to be localized near to the Zn vacancy rather than near to the Zn antisite (ZnGe). The calculated results suggested that the reported Hall effect and the photoluminescence data were compatible with the existence of 2 acceptors in the lattice (in a 3-level model) where one was significantly shallower (by 0.27eV, according to experiment). This result was in reasonable agreement with the calculated difference of 0.37eV.

P.Zapol, R.Pandey, M.Ohmer, J.Gale: Journal of Applied Physics, 1996, 79[2], 671-5