The influence of the silicon substrate temperature on structural and optical properties of thin-film cadmium sulfide formed with femtosecond laser deposition

CdS thin films have been grown on Si(1 1 1) substrates using femtosecond pulsed laser deposition (PLD). The crystalline quality and the surface morphology of the deposited CdS thin films have been characterized using X-ray diffraction (XRD) and atomic force microscopy (AFM). The photoluminescence (PL) of the CdS thin films was investigated by fluorescence spectra analysis. The influence of the substrates temperature in the range 100–600 °C on the structural and optical characterizations of CdS thin films have been systematically studied. The XRD and PL analysis show that the crystalline quality of the CdS thin films can be improved with increasing the substrates temperature to 450 °C, but further increase of the substrates temperature to 600 °C leads to the degradation of the crystalline quality. AFM results show that the surface roughness of CdS thin films can be increased with the substrates temperature increasing. In the corresponding fluorescence spectra, a blue shift of the CdS emission band is found, which may be a result of the quantum size effect.