Synthesis, analysis, and characterization of structural and optical properties of thermally evaporated chalcogenide a-Cu-Zn-Ge-Se thin films

Thin novel amorphous thin Cu25-x(ZnGe)(25-x)Se50+2x (CZGSe) films (0.0 <= x <= 10.0 at.%) are synthesized by thermal evaporation deposition technique under the vacuum of approximate to 10(-4) Pa with almost 500 nm thickness. Film samples are characterized by X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS) and spectrophotometric transmission measurements. XRD confirms the amorphous nature of films and EDS proves a fair compatibility between the detected and chosen compositional elements' percentages. The absorption coefficient values are found to be in the range of 10(4) cm(-1). Tauc's bandgap energy, E-g increases from 1.456 eV to 1.722 eV, while Urbach's energy, E-e shows a decrease from 0.032 eV to 0.015 eV. The refractive index of CZGSe films also decreases along all the studied spectral range. Wemple-DiDomenico and Sellmeier models are applied to study dispersion energies and related parameters. The oscillator resonance energy (E-o) and oscillator dispersion energy (E-d) shows inverse behaviour. The E-o values increase (2.939 eV-3.422 eV), but E-d values show a decrease (30.831 eV-24.342 eV). Many dispersion and nonlinear parameters are also calculated and discussed. The correlation between optical parameters of CZGSe films has been analyzed using Python programming. The obtained findings show the possibility of using these films in many optical applications.

Automated summary

This study investigates the optical properties of a thin film material and characterizes it using various techniques. The results show that the film possesses good amorphous nature and low refractive index, making it suitable for a variety of optical applications.