Two-dimensional distribution of the residual stress in MBE-grown InGaAs-GaAs strained-layer superlattices

摘要

Distribution of the residual stress in InGaAs/GaAs strained layer superlattices (SLSs) has been investigated by the micro-focus photoluminescence (PL) method and PL topography. Dark lines parallel or perpendicular to [011] direction were observed in the samples by PL topography. The density of dark lines was decreased as the thickness of In_(0.1)Ga_(0.9)As layers increased. Such dark lines were observed even in a sample whose thickness was thinner than critical value. These dark areas corresponded to the regions where the peak wavelength of PL spectrum was shifted to longer side because of tensile stress. These results were explained well by our proposed model. That is, tensile stress acts the top of mountainous regions of wrinkles which were formed by compressive stress caused by the difference of the lattice constant between InGaAs and GaAs.