講演情報
[25a-12K-5]Anomalous Photoluminescence Properties due to Strong Coupling of InAs/InAsSb In-Plane Ultrahigh-Density Quantum Dots
〇(DC)SIMJUI OON1, Naoya Miyashita1, Koichi Yamaguchi1 (1.UEC Tokyo)
キーワード：
quantum dots、photoluminescence、strong coupling
InAs ultrahigh-density (UHD) quantum dots (QDs) were grown on InAs(Sb) wetting layer (WL) on a GaAs (001) substrate using MBE. Closely-stacked QDs exhibited strong electron wavefunction coupling at interdot distances < 10 nm, leading to overlapping energy states at high temperatures. This caused coherent tunnelling and strong coupling between neighboring QDs, forming a continuous miniband across in-plane QDs. The InAs/InAsSb UHD QD sample had a QD density of 1×1012 cm-2, with adjacent QDs spaced < 4 nm apart, capped with a 60-nm non-doped GaAs layer. Temperature-dependent photoluminescence measurements of UHD QDs revealed deviations from the Varshni curve, indicating a dynamic process of strong coupling from higher to lower energy QD states as temperature increased. PL spectra shifts and decay times supported this evidence, showing a decline in lifetime for higher energy states (50-80 K) due to strong coupling initiation, and an increase for peak and lower energy states before 100 K, attributed to thermal delocalization. Above 100 K, a significant drop in decay time indicated non-radiative recombination and strong coupling in QD ground states.