New route for cadmium sulfide nanowires synthesis via pulsed laser ablation of cadmium in thiourea solution

Abstract

The synthesis of cadmium sulfide CdS nanowires NWs by laser ablation of cadmium target in thiourea solution is demonstrated for the first time. The effect of laser fluence on the structural, morphological and optical properties of CdS nanoparticles was investigated. The synthesized CdS nanowires were polycrystalline with pure hexagonal wurtzite phase; as confirmed by x-ray powder diffraction results. The 3.18–3.26 eV direct optical energy gap of CdS and the increase of CdS optical absorption were noticed to be function of laser fluence. The results revealed a blue shift of 0.86 eV in the absorption edge of CdS nanowires when prepared at 2.65 J cm−2. The infrared absorption spectra revealed the presence of Cd-S stretching vibration peak located at (525–700) cm−1. Raman spectra confirmed the presence of a sharp peak at 304 cm−1 with intensity increased at higher values of laser fluence. Photoluminescence at room temperature indicated an emission peak of CdS at 471 nm. The scanning electron microscopy SEM investigation of the synthesized CdS showed a mixture of hexagonal nanoparticles and nanowires arrays. Transmission electron microscopy TEM investigation revealed the formation of well-dispersed single CdS nanowires with diameter in the range (18–27) and tens of micrometers long. The effect of laser fluence on the performance of n-CdS NWs/p-Si heterojunction was investigated.