Photoluminescence study of InAs quantum dots with bimodal size distribution

다국어 초록 (Multilingual Abstract)

We have investigated photoluminescence (PL) spectra taken from a series of self-assembled
InAs/GaAs quantum-dot (QD) heterostructures with different InAs coverages by performing
excitation-power and temperature dependence measurements. The PL spectra exhibit a well-defined
doublet-like QD peak with invariable energy positions regardless of the coverage attributed to a bimodal
size distribution of small and large QDs. The power-dependent PL spectra show that the
high-energy peak is composed of two contributions, one from the excited state of large QDs and the
other from the ground state of small QDs, and the power dependence of high-energy peak becomes
stronger with increasing the amount of InAs. This indicates that, in as-grown InAs QD ensembles
grown under optimum growth conditions with appropriate InAs coverages, there can exist a specic
bimodal size distribution consisting of large and small QD groups whose sizes are fixed, but whose
numbers vary with the amount of InAs.