Stimulated emission of CdS nanowires grown by thermal evaporation

摘要

High-quality CdS nanowires with wurtzite structure were produced by thermal evaporation of CdS powder. The nanowires were core-shell structures, consisting of crystalline core and amorphous/ polycrystal shell. The intensity of the second-order longitudinal phonon mode in the Raman spectrum of the CdS nanowires is higher than that of the first-order mode due to exciton-phonon coupling. The photoluminescence of the CdS nanowires is power dependent, and the photoluminescence peak at 516.5 nm becomes narrower with increase in excitation power, indicating the stimulated emission characteristics of CdS nanowires. The population inversion generated by two-photon absorption is mainly attributed to the occurrence of stimulated emission.