Optical Properties of CdTe Thin Films

The optical constants (the refractive index n and the absorption constant K) and absorption coefficients x are measured on CdTe thin films in the wavelength range 500 to 2000 nm. Some parameters which affect these optical properties of thin films, such as the film thickness, substrate temperature, doping with impurities like In, BaF2, PbCI2 are also investigated. Effective crystallite size and strain are determined by the method of variance analysis of the X-ray diffraction line profiles on the same films. It is observed that there is an increase in optical band gap with decrease in crystallite size and increase in strain.