The effect of selenium ion concentration on zinc selenide thin films prepared by a photo-assisted chemical bath deposition method

Zinc selenide (ZnSe) thin films were deposited on non-conducting glass substrates at different selenium concentrations using a photo-assisted chemical bath deposition method. The films were deposited for 2.0 h at 80^◦C and annealed for 2.0 h at 250^◦C. X-ray diffraction (XRD) revealed a hexagonal structure with preferential orientation along the (002) plane, and the crystallite sizes were about 9–11 nm. Raman scattering showed longitudinal optical phonon modes due to the ZnSe, and the effect of the selenium concentration was noticed on the peak intensities of the XRD and Raman scattering studies. Optical analysis showed higher absorbance in the visible region than near the infrared spectrum, making the thin films good materials for selective absorber surfaces. The estimated bandgap ranged between 2.37 and 2.70 eV. X-ray spectroscopy confirmed the presence of the desired elements and revealed that the ratio of selenium to zinc declined after the sample was prepared with 0.6 M selenium ions. Photoluminescence studies revealed three emission peaks, which were due to defect state levels in the ZnSe. By varying the selenium concentration, the ZnSe was tuned to a reddish color emission, as confirmed by Commission Internationale de L’Eclairage (CIE) color chromaticity analysis. The selective absorption, wide bandgap, and emission properties suggest that the material is promising for light-emitting device applications.