Effect of deposition time on the optical properties of CdSe nanostructured films

Cadmium selenide nanostructured films were prepared using high-frequency magnetron sputtering method. All samples were deposited on quartz substrates in disk form with a radius of 16 mm. The temperature of the substrate was similar for all samples and kept at 180 °C. The deposition times were 3, 6, 9, 12 and 20 min. The effect of deposition time on the optical properties of CdSe nanostructured films were investigated by X-ray diffraction (XRD), optical absorption spectra (OAS), scanning electron microscope (SEM) and energy-dispersive X-ray analyzer (EDX). XRD analysis of the obtained samples exhibited a cubic structure with a preferred (200) orientation. The average crystallite size of the CdSe nanostructured films was determined using the Scherrer equation. The EDX shows that the CdSe nanostructured films are formed from the desired elements, and their distribution is uniform. SEM analysis shows that the surface morphologies of the CdSe nanostructured films were dependent on the deposition time. OAS was analyzed by the Tauc model. The absorption spectrum fitting (ASF) method was applied to estimate the optical band gap and Urbach energy of the CdSe nanostructured films. The optical band gap and Urbach energy was found to decrease with increasing deposition time.