The site distribution of amphoteric dopants in multiply-doped GaAs

A chemical thermodynamic approach is used to predict the site distribution and solubility of amphoteric dopants in multiply doped crystals of GaAs. The analysis is applied to experimental results of Greene and of Brozel et al. on GaAs crystals doped with Si and either Sn, Ge or Se. Excellent agreement with the electrically measured carrier concentrations is obtained. It is shown that, whilst Ge commonly behaves as a donor in singly doped GaAs, in the presence of a high silicon concentration it can contribute more acceptors than donors to the crystal. (orig./GMV)