Size distribution effects on self-assembled InAs quantum dots

We report on the unusual behaviors of the optical properties for self-assembled InAs/GaAs quantum dots (QDs) by using photoluminescence (PL) spectroscopy. Distinctive double-emission QD peaks are observed in the PL spectra of the samples grown on high growth-temperature condition. From the excitation power-dependent and temperature-dependent PL measurements, these double-emission peaks are 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.