Hydrogen defect states in gallium arsenide: ab initio calculations

Abstract

Ab initio calculations have been performed for the various hydrogen (or muonium) charge states in GaAs. The equilibrium geometry of H⁺, H⁰, and H⁻ states and relative energies for trigonally symmetric sites on (111) axis were determined within two configurations of Ga₇As₇ clusters. Effective core potentials were used on the Ga and As host atoms and all exterior bonds were terminated with hydrogens. The present results are compared to available experimental information with emphasis on recent Mu⁻ data, and to previous theoretical treatments. We obtain a highly stable H⁻ confined within a tetrahedral interstitial region with Ga nearest neighbours consistent with experimental findings.