Epitaxy of multimodal InAs/GaAs quantum dot ensembles

Abstract

Formation of a multimodal quantum dot (QD) ensemble by strained-layer epitaxy of InAs on GaAs with a thickness slightly exceeding the critical value for the onset of the 2D–3D transition is studied. Various growth parameters such as growth rate, growth temperature and duration of growth interruption after InAs deposition and prior to GaAs cap layer growth were varied systematically to investigate the effect on the multimodal QD ensemble. Multimodal features of the QD ensemble are not affected by a change of the InAs growth rate as long as QD formation starts after deposition. Increase of growth temperature well above 500 °C leads to a disappearance of multimodal features of the QD ensemble. Tuning of the emission energy of QD subensembles for fixed QD height is demonstrated by proper adjustment of growth conditions. Addition of small amounts of antimony supplied during QD growth leads to a more explicit multimodal structure of the QD ensemble.