Naoya MIYASHITA (宮下 直也)

Abstract

A simulation model of in-plane strong electronic coupling between adjacent quantum dots (QDs) was presented to verify the peculiar temperature dependence of photoluminescence (PL) energy in InAs ultrahigh-density (UHD) QDs. In this model, we focused temperature dependence of homogeneous broadening of QD energy levels and calculated the transition to in-plane QD strong coupling by using square mesh patterns of (100 × 100) QDs and experimental data on PL spectra and inter-QD nearest neighbor distance distribution. InAs UHD QDs were grown on GaAs substrates by molecular beam epitaxy. The temperature dependence of the PL energy of UHD QDs could be explained by the in-plane strong coupling model on the low-energy side of the QD energy spectrum, but it was found that the carrier redistribution effect also needs to be taken into account on the high-energy side of the spectrum. The presented simulation model is useful for predicting the in-plane strong coupling of QDs.

Abstract

InAs/InAsSb ultrahigh-density quantum dots (UHD QDs) with a density of were fabricated using MBE, and their photoluminescence (PL) properties were characterized. Through temperature dependences of PL energy, intensity and decay time of UHD QDs, it was found that in-plane strong coupling between adjacent QDs of excited and ground states due to homogeneous broadening of QD levels progressed above 60 K and above 100 K, respectively. The findings regarding the strong coupling at ground states were consistent with the temperature dependence of PL minimum energy outlined in appendix. In addition, abnormal phenomenon in PL full width at half maximum was attributed to the in-plane miniband formation resulting from strong coupling.