Free versus localized exciton in GaAs V-shaped quantum wires

We present a systematic investigation of continuous wave and transient photoluminescence in GaAs V-shaped quantum wires as a function of temperature, aimed to the understanding of the radiative recombination mechanism of the ground level (localized versus free-exciton recombination). Exciton localization is observed at low temperatures. Free-exciton polariton transitions are monitored at intermediate temperatures through the square root temperature dependence of the decay time. Exciton localization energy, density of localization centers and exciton intrinsic lifetime have been determined from the theoretical analysis of the transient photoluminescence, thus providing a simple quantitative method for the assessment of sample quality.