Linear and nonlinear optical properties of amorphous Se–Te–Sn–Cd films

This research work reports the rigorous studies of the various optical properties of Cadmium containing amorphous thin films (TFs) of multicomponent Se–Te–Sn system. The optical characteristics of prepared TFs are analyzed by using the experimental spectral data of reflection/transmission in the range 4000 Å to 25000 Å. Knowing the spectral variation of the dispersion parameters, we have determined the optical band gap Egopt and Urbach tail Ee. After the addition of Cd, The Urbach energy Ee value decreases for the parent Se–Te–Sn sample. The values of the optical bandgap for the present samples are found in the range from 1.24 eV to 1.43 eV with a reversal in trend at x = 4.