Effect of Cu incorporation on structural and optical properties of nanocrystalline CdSe (nc-CdSe:Cu) thin films

► nc-CdSe:Cu 1% and nc-CdSe:Cu 5% thin films are prepared by thermal evaporation technique. ► The composition of the thin films is determined by EDX. ► Optical band gap (Eg) decreases with increase in the Cu concentration. ► PL intensity enhances as the Cu concentration is increased to 5%. nc-CdSe:Cu 1% and nc-CdSe:Cu 5% thin films have been deposited on glass substrates by thermal vacuum evaporation using the Inert Gas Condensation (IGC) method. Transmission Electron Microscopy (TEM) analysis reveals that the particles are spherical in shape and average particle size increases as the Cu concentration increases. The atomic weight percentage of Cu is determined by the Energy Dispersive X-ray analysis (EDX). X-ray Diffraction (XRD) measurements indicate that the films exhibit hexagonal structure. The grain size calculated from XRD increases as the Cu concentration is increased to 5%. The optical band gap Egopt has been determined from the absorption coefficient values using the Tauc’s procedure. A decrease in the band gap is observed with increase of the Cu concentration. The refractive index (n) is determined from transmittance using the Swanepoel’s method. The refractive index is found to depend on Cu concentration. The Photoluminescence (PL) spectral variation at different concentrations of Cu is studied.