Photoluminescence study on the growth of self-assembled InAs quantum dots: Formation characteristics of bimodal-sized quantum dots

We report a photoluminescence (PL) study on the growth process of self-assembled InAs quantum dots (QDs) under various growth conditions. Distinctive double-peak feature was observed in the PL spectra of the QD samples grown at the relatively high substrate temperature. From the excitation power-dependent PL and the temperature-dependent PL measurements, the double-peak feature is associated with the ground-state transitions from InAs QDs with two different size branches. In addition, the variation in the bimodal size distribution of the QD ensembles with different InAs coverage is demonstrated.