A proposed model to explain impurity-induced layer disordering in AlAs-GaAs heterostructures

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Abstract
Impurity-induced disordering of III-V compound semiconductor quantum well heterostructures and superlattices has been extensively studied. However, the theories proposed to explain this phenomenon have dealt primarily with vacancy diffusion mechanisms and have not succeeded in explaining all the experimental observations satisfactorily. In this communication, we propose a two-atom ring mechanism of diffusion based on a simplified model of covalent bonding in III-V compound semiconductors and suggest that the phenomenon of intermixing is a consequence of a lowering in the activation energy due to coulombic interactions between the substitutional impurity atoms and the host atoms. This mechanism is consistent with experimental observations and is able to predict the behavior of other dopants. The additive effect of the simultaneous presence of different dopants can also be explained by this theory which could possibly be used to achieve controlled layer disordering for use in device technology.