Extraction of thickness, linear and nonlinear optical parameters of Ge20+Se80- thin films at normal and slightly inclined light for optoelectronic devices

Abstract

In this framework, a novel Ge20+xSe80-x thin films ~890 nm, with (x = 5, 10, 15, 20, 25, and 30 at. %) were synthesized via thermally evaporation method at 298 K. The elemental ratios of Ge–Se thin films have been checked by EDX analysis and also the amorphous natural was confirmed through X-Ray Diffractometer, XRD. In thin films belonging to the glass chalcogenide, in the case of existence of interference in the optical measurements-namely, transmittance, T and reflectance, R spectra-often the dispersion refractive index, n(λ) and the thickness of the thin film, d were computed based on the spectrum of transmittance or reflectance and also the wavelength along with the optical measurements. In this work, the real optical constant n(λ) and film's thickness of Ge–Se thin films have been computed utilizing the wavelength measurements of the normal and slightly inclined incidence light solely. Then, the linear optical parameters such as Tauc's energy Eg and Urbach's energy Ee, the linear imaginary optical constant, namely, absorption index or extinction coefficient kex, the linear dispersion parameters, namely, the single oscillator energy Eo and the dispersion energy Ed and the non-linear optical constant or so called the second-order of refractive index n2 have been determined. The optical dispersion dndλ, phase velocity vp, group velocity Ug, Magneto-Optical Constant or Verdet coefficient V(λ) and the positions of the energy levels have been discussed in detail.