Optical transition and carrier relaxation in a type-II InAs/GaAsSb quantum dot layer

In-plane ultrahigh-density InAs quantum dots (QDs) were grown on the GaAsSb buffer layer by molecular beam epitaxy. Photoluminescence (PL) properties of the InAs QDs/GaAsSb layer were measured under 1.58 eV and 1.44 eV light excitations, which were GaAs and InAs QD/wetting layer (WL)/GaAsSb excitations. For the GaAs excitation, PL spectra were due to a type-II transition from the ground state (GS) of the QD conduction band to the GaAsSb valence band. This PL spectrum did not depend on the measurement position because of the electron filling into lower GS levels. For the InAs QD/WL excitation, PL spectra originated from the crossed transitions of localized bound excitons between QD excited states (ES) and the WL valence band, and depended on the measurement position. Furthermore, excitation power and temperature dependences of the PL spectra were measured to discuss carrier dynamics. (C) 2018 The Japan Society of Applied Physics