Optical study of GaAs quantum dots embedded into AlGaAs nanowires

We report the photoluminescence characterization of GaAs quantum dots embedded in AlGaAs nanowires. Time-integrated and time-resolved photoluminescence was measured for both arrays and single quantum dot/nanowires. The optical spectroscopy data show the influence of growth temperature on the distribution of diameters and the presence of different crystalline phases in the AlGaAs nanowires. By means of scanning and transmission electron microscopy and photoluminescence we observed that the growth temperature has a strong influence on the homogeneity of the nanowires, in size and density. In photoluminescence spectra of a single quantum dot, spectral diffusion was observed in the exciton line. Formation of various crystalline phases in the AlGaAs nanowires leads to very long decay times for the nanowire luminescence, around 20 ns.