Structural and optical investigation of Cd_4Se_(96-x)S_x (x = 4, 8, 12) chalcogenide thin films

摘要

Cd_4Se_(96-x)S_x 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 polycrys-talline 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.