Carrier Dynamics of a Type-II Vertically Aligned InAs Quantum Dot Structure with a GaAsSb Strain-Reducing Layer

The carrier dynamics of vertically aligned InAs/GaAsSb type-II quantum dot (QD) structure are comprehensively analyzed by time-resolved photoluminescence (TRPL) in this study. A columnar InAs QD structure with an overgrown layer of GaAsSb is proposed to enhance the thermal stability and carrier lifetime through the type-II energy band alignment and carrier tunneling effect. The carrier lifetimes of columnar QD structures were in accordance with the PL spectra in wavelength-dependent TRPL measurements because of the electronic coupling effect and the dot-size-dependent oscillator strength. The improved results in this work make columnar type-II QDs promising candidates for novel optoelectronic device application.