Analysis of defect-free GaSb/GaAs(001) quantum dots grown on the Sb-terminated (2 × 8) surface

Abstract

Multilayer and single layer GaSb/GaAs(001) quantum dot structures were grown on an Sb-terminated (2 × 8) surface reconstruction and compared to those grown on an As-terminated (2 × 4) surface reconstruction. Uncapped quantum dots grown on the (2 × 8) surface were approximately 25% smaller in diameter and had a larger width/height aspect ratio. Quantum dots grown on both surfaces were defect free at the quantum dot/spacer layer interface. The dots did not appear to be fully compact when imaged by transmission electron microscopy, which may be due to dissolution and/or quantum ring formation. The quantum dot photoluminescence peak for dots grown on the (2 × 8) surface was brighter but at the same energy as that of dots grown on the (2 × 4) surface. This was likely the result of a higher areal density of dots on the (2 × 8) surface and a lower tendency for them to intermix during capping, resulting in dots of similar size for both samples after capping. Quantum dots grown on the (2 × 8) surface also displayed greater morphological stability when quenched in the absence of Sb.