It was shown, using quantum molecular dynamics calculations, that the formation energies of vacancies in semiconductor alloys depended strongly upon the chemical identities of their nearest-neighbor atoms. For example, in AlGaN alloys, the Ga-terminated vacancy was lower in energy than the Al-terminated one, by 2.8eV. This led to unexpectedly strong preferences for vacancy termination in semiconductor alloys. The results also predicted that local segregation would occur at grain boundaries and dislocations.

Segregation Effects at Vacancies in AlxGa1-xN and SixGe1-x Alloys. P.Bogusławski, J.Bernholc: Physical Review B, 1999, 59[3], 1567-70