Investigation the optical properties of thin films of the chalcogenide compound GeSe2-xCdx

Abstract

In this study, thin films of the chalcogenide compound with different rates  (x =0.3, 0.5, 0.7, 0.9, 1.0) had been prepared using the thermal evaporation method. The samples had been checked using the X-ray diffraction technique (XRD), which showed that the samples were of a polycrystalline nature, with an amorphous phase for the sample x = 0.3. The optical transmission  spectra had been recorded, in the spectral range of [300-2500 nm] to determine some of the optical parameters like:  dispersion of the two components of both complex refractive index (n̂=n-ik), complex dielectric constant (ε₁ and ε₂), energy band gap (E_g), and Urbach energy (E_u).

 It was observed that the band gap decreases with the increase of cadmium concentration in the studied compound, and this decrease was explained by the average mean energy.