Studying the Optical and Electrical Properties of CuGa_0.5In_0.5Se₂ Chalcopyrite Due to Substrate Temperature and Gamma Irradiation

Abstract

Thin films of chalcopyrite CuGa0.5In0.5Se2 (CGIS) with thickness ≈2000 Å are prepared by thermal evaporation method at different values of substrate temperature (Ts) 373, 473, and 573 K. Crystal structure and elemental chemical composition are examined by X‐ray diffraction and energy dispersive X‐ray analysis, respectively. The optical constants of the films in the spectral range 200 nm ≤ λ ≤ 2500 nm are calculated. It is found that the transmittance and band gap (Eg) decrease with increasing the substrate temperature (Ts) while Urbach energy increases with the increase of Ts. The Wemple–DiDomenico (WDD) model is used to calculate the oscillator parameters. Furthermore, the prepared films are irradiated with γ‐ray at different doses 2, 4, and 8 kGy. The results reveal that the optical band gap increases and Urbach energy decreases as γ‐doses increase. Finally, the substrate temperature and γ irradiation upon the electrical resistivity are studied. Consequently, it is found that the electrical resistivity decreases with the increase of both the substrate temperature and γ‐irradiation. In conclusion, the γ‐irradiation stimulates a change in optical parameters and electrical resistivity which can be utilized for industrial dosimetric purposes.