Comparative studies of ion-induced mixing of GaAs-AlAs superlattices

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Abstract
The species dependence of ion-induced superlattice mixing has been examined in AlAs-GaAs superlattice samples grown by molecular beam epitaxy. The interdiffusion of the superlattices induced by ion implantation with comparable ranges, doses, and subsequent thermal anneals were measured with secondary ion mass spectrometry. The effects of elements of comparable mass (Ga, As, and Ge) and comparable valence (Si and Ge) were studied. The experimental results show that Ga and As implantation cause primarily collision-induced mixing, while Ge implantation results in collision-induced mixing with additional impurity-induced mixing beyond the implant range. In comparison with Ge, Si-induced mixing is similar in nature though there is significant difference in the depth and extent of the mixing. The extent of mixing is found to depend on the local Ge or Si concentration.