Time-resolved photoluminescence study of InGaAs/GaAs quantum well-dots with upconversion method

For the first time we show time-resolved photoluminescence dependencies with 0.2 ps resolution for the novel type of InGaAs/GaAs quantum-sized heterostructures, referred to as quantum well-dots (QWDs). Photoluminescence upconversion method, that allows achieving time resolution up to 0.2 ps, was used to obtain time-resolved spectra for light (lh) and heavy hole (hh) optical transitions of QWDs. We concluded that the capture of charge carriers to the lh and hh states of QWDs occurs simultaneously in the time range of ~ 10 ps and is probably limited by carrier diffusion in the matrix. The characteristic time of photoluminescence decay for the hh state (3 ns) was found to be greater than that of lh one (2 ns).