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 (I-Ga). This kick-out reaction provides the possibility to determine I-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 I-Ga sinks. The present study prevents such defect formation by utilizing Zn-doped GaAs powder as diffusion source. Measured two-stage profiles show that under these conditions Zn diffusion at 906 degrees C is controlled by I-Ga(3+) in addition to I-Ga(2+). Analysis of the profiles yield quantitative data on Ga- and Zn-related diffusivities, concentrations of I-Ga as well as the corresponding electronic transition energy.