Transition-selective photoluminescence of InSb quantum dots on GaSb substrate

Transition-selective photoluminescence (TSPL) spectroscopy was applied to InSb quantum dots (QDs) grown on GaSb substrates to resolve the overlapping photoluminescence (PL) transitions that were indistinguishable in conventional measurements. TSPL is a frequency-domain measurement technique in which the excitation laser intensity is modulated. Based on the modulation frequency dependence of the PL intensity and phase, the measured PL lifetimes of the InSb QDs and GaSb were approximately 3 and 5 ns, respectively. The PL originating from the impurity bands in GaSb was successfully isolated from those emitted by band-to-band transitions and InSb QDs; these PL features were otherwise obscured by adjacent transitions. The selection of these transitions was attributed to detection-phase control that enabled selective suppression of unwanted transitions. These results demonstrate that TSPL is a powerful technique for extracting transition-specific information from semiconductor heterostructures.