Recent diffusion experiments had shown that the predominant charge states for GaI diffusion in GaAs should be 0 and +1; with surprisingly high enthalpy barriers of 5.45 and 5.80eV, respectively. Using the activation-relaxation technique, coupled with an ab initio code, possible migration pathways and barriers for these 2 charge states were identified. In the +1 charge state, 2 different migration paths were observed between tetrahedral sites surrounded by Ga atoms (tetra[Ga−Ga]); implying either a tetrahedral interstitial surrounded by As atoms (tetra[Ga−As]) or a <111>-oriented split configuration, with total barriers of 1.4 and 1.3eV, respectively. Including the formation energy, the enthalpy barriers that were found were lower than the experimentally derived values. The possible causes and significance of this discrepancy were analyzed, and a partial explanation was offered which was based upon the correction method used for finite-size effects.

Numerical Characterization of the Ga Interstitial Self-Diffusion Mechanisms in GaAs. K.Levasseur-Smith, N.Mousseau: Journal of Applied Physics, 2008, 103[11], 113502