Limits to N-Type Doping in Ge: Formation of Donor-Vacancy Complexes
Vacancies and interstitials in semiconductors play a fundamental role in both high temperature diffusion and low temperature radiation and implantation damage. In Ge, a seri- ous contender material for high-speed electronics applications, vacancies have historically been believed to dominate most diffusion related phenomena such as self-diffusivity or impurity mi- gration. This is to be contrasted with silicon, where self-interstitials also play decisive roles, despite the similarities in the chemical nature of both materials. We report on density func- tional calculations of the formation and properties of vacancy-donor complexes in germanium. We predict that most vacancy-donor aggregates are deep acceptors, and together with their high solubilities, we conclude that they strongly contribute for inhibiting donor activation levels in germanium.
Andreas Öchsner and Graeme E. Murch
J. Coutinho et al., "Limits to N-Type Doping in Ge: Formation of Donor-Vacancy Complexes", Defect and Diffusion Forum, Vols. 273-276, pp. 93-98, 2008