A re-examination was made of the static properties of vacancies in GaAs by means of first-principles density-functional calculations, using localized basis sets. The calculated formation energies yielded results that were in good agreement with recent experimental and ab initio calculations and provided a complete description of the relaxation geometry and energetics for various charge states of vacancies from both sub-lattices. The Ga vacancies were stable in the 0, –1, –2 and –3 charge states, but VGa3- remained the predominant charge state for intrinsic and n-type GaAs; thus confirming the results of positron annihilation. The As vacancies exhibited 2 successive negative-U transitions making only +1, –1 and –3 charge states stable, while the intermediate defects were metastable. The second transition (–/–3) led to a resonant bond relaxation of VAs3-; similar to the one identified for Si and GaAs divacancies.

Self-Vacancies in Gallium Arsenide - an ab initio Calculation. F.El-Mellouhi, N.Mousseau: Physical Review B, 2005, 71[12], 125207 (12pp)