Optical properties of vacuum evaporated CdxSn1−xSe polycrystalline thin films: influence of composition and thickness

Polycrystalline CdxSn1−xSe material is synthesized by melt growth technique for various x values and thin films are prepared by vacuum evaporation technique. Optical transmittance measurements have been made on thin films of CdxSn1−xSe, with x=0,0.3,0.75 and 1 for various thicknesses. The studies reveal that these thin films have a direct allowed band gap energy and the indirect band gap energy is improbable. The band gap energy increases with decrease in thickness in all the compositions and it is attributed to the quantum size effect.