Optical and structural properties of InGaSb/GaAs quantum dots grown by molecular beam epitaxy

We present the results of an investigation into the growth of InGaSb/GaAs quantum dots (QDs) by molecular beam epitaxy using migration-enhanced epitaxy. Surface atomic force microscopy and cross-sectional transmission electron microscopy show that the QDs undergo a significant change in morphology upon capping with GaAs. A GaAs ‘cold capping’ technique was partly successful in preserving QD morphology during this process, but strong group V intermixing was still observed. Energy-dispersive x-ray spectroscopy reveals that the resulting nanostructures are small ‘core’ QDs surrounded by a highly intermixed disc. Temperature varying photoluminescence measurements indicate strong light emission from the QDs, with an emission wavelength of 1230 nm at room temperature. Nextnano 8x8 k.p calculations show good agreement with the PL results and indicate a low level of group-V intermixing in the core QD.