Point defects, diffusion mechanisms, and superlattice disordering in gallium arsenide-based materials
This article reviews recent progresses in our understanding of the mechanisms of Ga self-diffusion and impurity diffusion in GaAs, and of the disordering of GaAs/AlGaAs superlattices. Gallium self-diffusion and Al-Ga interdiffusion under intrinsic and n-doping conditions are governed by the triply negatively charged group HI sublattice vacancies V3-Ga, while under heavy p-doping conditions most likely by the doubly positively charged self-interstitial I2+Ga. The GaAs/AlGaAs superlattice disordering enhancement observed under n-doping by Si or by Te is due to the Fermi-level effect that increases the V3-Ga concentration, while the observable or not observable disordering enhancement under p-doping by Zn or by Be is due to the combined effects of the Fermi-level, which increases the I2+Gaconcentration, and the dopant in-diffusion or out-diffusion induced supersa-I2+Ga turation or undersaturation, respectively. In consistency with the Ga self-diffusion mechanism in GaAs, diffusion of the Si donor atoms occupying Ga sitesis primarily also governed by V3-Ga, while Si acceptor atoms occupying As sites, which is a minority fraction of the total, diffuses via a negatively charged As sublattice point defect species. The interstitial-substitutional p-type dopants Zn and Be diffuse via the kick-out mechanism. Their diffusion induces an I2+Gasupersaturation and undersaturation, respectively, under the in-diffusion and out-diffusion conditions. © 1991 by CRC Press, Inc.
Tan, TY; GÖsele, U; Yu, S
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