Exciton-Related Photoluminescence and Lasing in CdS Nanobelts

Abstract

We present exciton-related optical studies of cadmium sulfide (CdS) nanobelts. Photoluminescence (PL) properties of CdS nanobelts are analyzed by using high spectral resolution spectroscopy from 10 to 300 K. The PL spectrum at 10 K shows rich spectral features which are identified, by means of temperature-dependent spectral evolution, to be the recombinations of free excitons, excitons bound to neutral impurities, and donor–acceptor pairs. The strong excitonic emission in our samples enables the observation of random lasing action at room temperature with a lasing threshold pump density of ∼0.1402 ± 0.0060 MWcm –2 . Notably, temperature-dependent pump thresholds exhibit a characteristic temperature as high as 195.3 ± 12.7 K, implying a good thermal stability of the lasing behavior and potential high temperature operation. Our studies not only elucidate the intrinsic physical properties of our high quality nanomaterial but also reveal the promising applications in photonics.