Use of zinc diffusion into GaAs for determining properties of gallium interstitials

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 (IGa). This kick-out reaction provides the possibility to determine IGa transport properties from Zn diffusion experiments in virtually perfect GaAs but previous attempts were frustrated by diffusion-induced generation of microstructural defects acting as IGa 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 IGa³⁺ in addition to IGa²⁺. Analysis of the profiles yield quantitative data on Ga- and Zn-related diffusivities, concentrations of IGa as well as the corresponding electronic transition energy.