First-principles calculations were used to study the As–vacancy interaction and the ring mechanism of diffusion in the presence of Ge in Si in neutral and positively charged states. It was discovered that the vacancy barrier decreases substantially when the vacancy hops around the ring. It was believed that this indicated that the existence of As atoms could lower the vacancy migration barrier. The vacancy migration barrier was also decreased when Ge atoms were present in the vicinity. Calculations were made of the As–vacancy ring mechanism in crystalline Ge and it was found that the formation energy and migration barriers of the vacancy were smaller than those in crystalline Si. These results supported the conclusion that As diffusion could be enhanced by the presence of Ge, and provided physical insight into As diffusion in Si1-xGex.

First-Principles Study of As–Vacancy Interaction and the Ring Mechanism of Diffusion in the Presence of Ge in Si. J.Zhang, Y.Ashizawa, H.Oka: Journal of Physics - Condensed Matter, 2006, 18, 4879-86