Diffusion of Nitrogen from a Buried Doping Layer in Gallium Arsenide Revealing the Prominent Role of As Interstitials

We report the first measurements of N diffusion in GaAs. GaAs films with a buried N doping layer were grown by molecular beam epitaxy and diffusion annealed between 808 and $880°\mathrm{C}$ in As-rich ambient. Nitrogen distributions determined by secondary ion mass spectroscopy reveal a marked non-Gaussian broadening of the as-grown peak. Computer modeling yields strong evidence for the kick-out diffusion mechanism involving interstitial ( ${\mathrm{N}}_i$) substitutional ( ${\mathrm{N}}_s$) exchange assisted by As interstitials ( $I_{\mathrm{As}}$). This allows us to deduce the $I_{\mathrm{As}}$-related diffusion coefficient of As in GaAs. Comparison with existing As tracer diffusivities points to a substantial contribution of $I_{\mathrm{As}}$ to As diffusion in GaAs.