Structural and optical investigation of Cd4Se96−xSx (x = 4, 8, 12) chalcogenide thin films

Cd4Se96−xSx with x = 4, 8, 12 chalcogenide semiconductor has been prepared by melt-quenching technique. Thin films were deposited by thermal evaporation technique on ultra clean glass substrates under a high vacuum of 10−6 Torr and were characterized by XRD, SEM, FTIR and Raman spectroscopy. XRD confirms the prepared films are in nanoscale region having polycrystalline nature with preferred orientation along (002) plan. Optical properties (optical band gap, absorption coefficient, extinction coefficient, refractive index) were investigated in the frequency range of 190–1100 nm. Analysis of the optical measurement shows that the non-direct transition is dominant. It is observed that the optical band gap increase with sulfur (S) concentration. The Dark conductivity as a function of temperature in the temperature range 300–390 K was investigated, which shows that it is thermally activated process. The conductivity increases on the incorporation of Sulfur content, which may be due to shift in Fermi level.