The fast diffusion of Zn into GaAs has recently been attributed to a minor fraction of Zn interstitials changing over to Ga sites thereby producing interstitial Ga (${\mathit{I}}_{\mathrm{Ga}}$). This kick-out reaction provides the possibility to determine ${\mathit{I}}_{\mathrm{Ga}}$ transport properties from Zn diffusion experiments in virtually perfect GaAs but previous attempts were frustrated by diffusion-induced generation of microstructural defects acting as ${\mathit{I}}_{\mathrm{Ga}}$ sinks. The present study prevents such defect formation by utilizing Zn-doped GaAs powder as the diffusion source. Measured two-stage profiles show that under these conditions Zn diffusion at 906 °C is controlled by ${\mathit{I}}_{\mathrm{Ga}}^{3+}$ in addition to ${\mathit{I}}_{\mathrm{Ga}}^{2+}$. Analysis of the profiles yield quantitative data on Ga- and Zn-related diffusivities, concentrations of ${\mathit{I}}_{\mathrm{Ga}}$ as well as the corresponding electronic transition energy.

• Received 15 May 1995

DOI:https://doi.org/10.1103/PhysRevB.52.11927