Investigation of defect structure of InGaNAsSb/GaAs quantum wells

The results of the photoluminescence (PL) and the high-resolution X-ray diffraction (HRXRD) investigations of point and extended defects in strained InGaAs(N)Sb/GaAs quantum well (QW) structures grown at 478-505 °C are presented. HRXRD studies prove a good quality of heterointerfaces in all samples that is attributed to Sb-surfactant effect. The PL investigations show that the increase of the growth temperature of N-containing QWs leads to the increase of potential fluctuations in QW due to the increase of composition disorder. In the PL spectra an intense band caused by excitonic transitions related with N-related clusters in GaAs barriers is found. HRXRD mapping in symmetrical 004 reflections reveals the oscillation of interference picture in [110] direction around the normal to (100) surface known as a “wiggle”. The mapping indicates the formation of elastically coupled domains which are elongated in [¯110] direction and are supposed to be cased by lateral composition modulations in the QW. It is proposed that a “wiggle” explained by the change of slopes of crystallographic planes with the depth is the result of competition of two factors - a symmetry of the surface stress tensor and a symmetry of bulk elastic moduli of a substrate material.