Thermally-activated charge reversibility of gallium vacancies in GaAs

Abstract

The dominant charge state for the Ga vacancy in GaAs has been the subject of a long debate, with experiments proposing $-$1, $-$2 or $-$3 as the best answer. We revisit this problem using {\it ab initio} calculations to compute the effects of temperature on the Gibbs free energy of formation, and we find that the thermal dependence of the Fermi level and of the ionization levels lead to a reversal of the preferred charge state as the temperature increases. Calculating the concentrations of gallium vacancies based on these results, we reproduce two conflicting experimental measurements, showing that these can be understood from a single set of coherent LDA results when thermal effects are included.

arXiv comment4 pages, 4 figures

References in corpus (4)

• Managing the supercell approximation for charged defects in semiconductors: finite size scaling, charge correction factors, the bandgap problem and the ab initio dielectric constant
• Self-vacancies in Gallium Arsenide: an ab initio calculation
• Structure and vibrational spectra of carbon clusters in SiC
• First-principles study of As interstitials in GaAs: Convergence, relaxation, and formation energy

Cited by in corpus (1)

• Charge-dependent migration pathways for the Ga vacancy in GaAs