Photoluminescence characteristics of quantum dots with electronic states interconnected along growth direction

Abstract

We report the excitonic photoluminescence (PL) characteristics in multiple stacked quantum dots (QDs) fabricated by using a strain compensating technique. The PL characteristics of QD excitons vary according to the spacer layer thickness; with decreasing spacer layer thickness, the PL intensity decreases and the PL decay time becomes longer. Furthermore, the intensity ratio of the transverse-magnetic to transverse-electric modes in the PL emission from the cleaved edge surface increases. As the spacer layer thickness decreases, the degree of overlap of the electron envelope functions owing to tunneling becomes larger, which consequently interconnects the QDs along the growth direction. This interconnection induces a large change in the oscillator strength of the QD excitons and the PL characteristics. Therefore, we concluded that the optical characteristics can be controlled drastically by changing the spacer layer thickness.