Optical characteristics and dispersion parameters of thermally evaporated Ge50In4Ga13Se33 chalcogenide thin films

Ge50In4Ga13Se33 glassy composition was fabricated using the chemical composition and the melt quenching technique. Using X-ray diffraction (XRD) and energy dispersive X-ray (EDX) analysis, the structural characterization of the thermally evaporated films with different thicknesses (126-745 nm) used in this study was determined. Transmittance T(lambda) spectrum was obtained in the range of wavelength from 400 nm to 2500 nm at room temperature. Swanepoel's method was employed to evaluate the optical constants, refractive index n and extinction coefficient k. From the obtained data of n, transmission coefficient T-C and reflection loss factor R-L were determined. Optical band gap E-g(opt) and Urbach tail E-u were determined using Tauc's extrapolation method. The calculated value of the transition power factor p revealed the indirect optical transition indicated in this study. The Wemple-DiDomenico parameters are also reported for the composition under study. The dependency of real epsilon(1) and imaginary epsilon(2) components of dielectric constant, dissipation factor tan delta, relaxation time tau volume and surface energy loss functions and the optical conductivity sigma(op)(t), on photon energy hv were studied also for Ge50In4Ga13Se33 films. In addition, the 3rd order non-linear optical susceptibility chi((3)) and non-linear refractive index n(2) were determined.