Structural properties of BeTe/ZnSe superlattices

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Abstract
The structural properties of BeTe/ZnSe short-period superlattices grown by molecular-beam epitaxy on (001)-oriented GaAs substrates were investigated. Different growth modes were used which influence the morphology and chemical transition at the interfaces. The BeTe/ZnSe superlattices were examined by optical microscopy, conventional and high-resolution transmission electron microscopy, x-ray diffractometry, and atomic force microscopy, with a particular emphasis on the defect generation mechanisms and the effects of different bond configurations at the interfaces. The critical thicknesses largely exceed the theoretical values for the plastic relaxation by misfit dislocations. The mismatch is relaxed by cracks preferentially oriented along one particular 〈110〉 direction under tensile stress conditions. In order to quantify the abruptness of the chemical transition at the interfaces and to determine the layer thicknesses accurately, high-resolution transmission electron micrographs were evaluated by correspondence analysis.