Effect of Tb Doping on Structural and Optical Properties of (Cd0.8-Zn0.2)S Films Deposited Through a Chemical Route
Tb-doped (Cd0.8-Zn0.2)S films have been prepared on glass substrates at 60°C by a chemical bath deposition technique. The effect of variation in the molar concentration of terbium (Tb) on the optical properties of the deposited films has been investigated and is discussed. The films have been characterized through x-ray diffraction (XRD), scanning electron microscopy (SEM), UV–Vis absorption and photoluminescence (PL) emission spectral studies. Prominent diffraction lines of CdS and ZnS with maximum orientation towards (111)c plane of CdS are observed in XRD patterns. Particle sizes calculated from XRD studies using Scherrer’s formula are found to be in the nano-range. The SEM micrographs of bulk film showed a layered structure, while a honey-comb structure with thickness of layers in the nano-range is seen for the deposited films. From the optical absorption spectra, a blue shift in the absorption edge is distinctly observed in the nanocrystalline films as compared to bulk film, suggesting the involvement of a quantum confinement effect. PL emission spectra showed distinct emission peaks for bulk and nanocrystalline films. PL emissions due to transitions within Tb3+ levels are also observed. The characteristic green emission peak due to 5D4-7F2 transition in Tb at 620 nm is observed in all three cases. Various studies suggest that the deposited films have potential applications in photo-electronic devices.