Density-functional theory study of Au, Ag and Cu defects in germanium

Gold, silver and copper defects in germanium are modeled using density functional theory. The structures and electrical properties of the substitutional metals are calculated in excellent agreement with experiment. Interstitial Au, Ag and Cu are found to be shallow donors, in disagreement with a previous assignment of Cui to a hole trap in the lower half of the gap. Substitutional-interstitial metal (Mi-Ms) pairs and metal-vacancy pairs (Ms-V) are also investigated.