Density functional study of the effects of doping and stoichiometry on gallium diffusion in gallium arsenide

Previous experimental [1-4] and theoretical [5,6] work on the properties of diffusion of gallium within gallium arsenide has produced some results that are apparently at odds with each other. We present results of a wide theoretical survey of the point defects that form in this material with special attention paid to the formation and diffusion of excess-gallium-related point defects. In this study we applied density functional theory in the local density approximation [7]. Diffusion was examined through the use of the nudged elastic band method [8]. After considering the accuracy of the approximations used, the calculations yield information compatible with the experimental situation and capable of shedding light on areas of apparent disagreement.\\[4pt] [1] G B\"{o}sker \emph{et al.}, Phys.\ Rev.\ B {\bf{52}}, 11927 (1995). [2] G B\"{o}sker \emph{et al.}, J. Appl.\ Phys.\ {\bf{86}}, 791 (1999). [3] H Bracht and S Brotzmann, Phys.\ Rev.\ B {\bf{71}}, 115216 (2005). [4] H Bracht \emph{et al.}, Physica B {\bf{308-210}}, 831 (2001). [5] K Levasseur-Smith and N. Mousseau, J. Appl.\ Phys.\ {\bf{103}}, 113502 (2008). [6] PA Schultz \emph{et al.}, Mod.\ and Sim.\ in Mat.\ Sci.\ and Engr.\ {\bf{17}}, 084007 (2009). [7] G. Kresse and J. Hafner, Phys. Rev. B {\bf{47}}, 558 (1993); \emph{ibid.} {\bf{49}}, 14251 (1994). [8] H. J\'{o}nsson \emph{et al.}, ``Classical and quantum dynamics in condensed phase systems,'' (World Scientific, 1998) Chap.\ 16, pp. 385-404.