Determination of the basic optical parameters of CdX (X=Se, S) thin films prepared with low concentration precursor solutions

Abstract

CdSe and CdS thin films, one of the II-VI group semiconductor compounds, were successfully grown by electrochemical deposition method using low concentrations of precursor solutions. Optical properties of the fabricated thin films were investigated in the 300 -850 nm wavelength range. The absorption coefficients of CdSe and CdS thin films were found to be as 5.8 x 10 5 m -1 and 8.9 x 10 6 m -1 , respectively, and direct energy band gaps these thin films were determined 2.72 eV and 2.75 eV. While the average transmission value of the CdSe was 85%, that of the CdS was 8%. Additionally, extinction coefficient values of the CdSe and CdS thin films were defined as 0.033 and 0.51, respectively and refractive index values of these were determined as 1.14 and 1.35. Besides, optical dielectric constants of thin films were examined. While the real dielectric constant, imaginary dielectric constant, dielectric loss and optical conductivity values of the CdSe were 1.24, 0.05, 0.004 and 1.38x10 14 , those of CdS thin film were 1.51, 0.94, 0.64 and 2.49x10 15 .