Density functional theory with the local density approximation including on-site Coulomb interactions was used to calculate the formation energy of the neutral and charged vacancy in Ge as a function of the Fermi level. The calculations suggested that vacancies in Ge were multiple-level acceptors with a first level at 0.02eV and a second level at 0.26eV above the valence band maximum; in agreement with published experimental data. The formation energies of the neutral and charged vacancies agreed well with the experimental values estimated from quenching experiments.

First Principles Calculations of the Formation Energy and Deep Levels Associated with the Neutral and Charged Vacancy in Germanium. P.Śpiewak, J.Vanhellemont, K.Sueoka, K.J.Kurzydłowski, I.Romandic: Journal of Applied Physics, 2008, 103[8], 086103