Analysis of GaSb/AlSb strained layers superlattices using small angle X-ray diffraction

Strained layer superlattices of GaAs and AlSb are analysed by augmenting (004) double crystal X-ray diffraction with small angle diffraction. The measurement of layer widths by the latter method will be shown to be more accurate since it does not involve any assumption on the state of strain. The results are confirmed by photoluminescence at 77 K. Actual strain is calculated from the average lattice parameter and the AlSb mole fraction obtained by (004) and small angle diffraction, respectively. The shift in the heavy hole band gaps of the layers due to the in-plane bi-axial stress is then discussed.