Changes in gamma attenuation behaviour of sol-gel derived CIGS thin film irradiated using Co-60 radioisotope

Abstract

Copper indium gallium (di) selenide-Cu(In, Ga)Se2 (CIGS) thin films were fabricated on soda-lime silicate glass substrates using a layer-by-layer sol-gel dip-coating method. The irradiation procedure was handled using a certified Co-60 radioisotope at two different absorbed dose levels (at 0,03 and 0,05 Gray (Gy)) to examine the enhancements of optical and electrical properties of the CIGS thin films. Cs-137 (with 0,662 MeV) and Co-60 (with ∼1,25 MeV) radioisotopes were used to evaluate the effect of the absorbed dose on CIGS thin films with different thicknesses by the gamma transmission technique. The irradiated CIGS thin films exhibited an improved optical band gap and electrical resistivity at the optimal layer thickness. This improvement occurs due to the enhancement of crystalline properties in comparison with those of non-irradiated CIGS thin films. The CIGS thin film of ∼300 nm (11 layers) thickness was suitable for comparing changes in the linear attenuation coefficient after the irradiation process at two different absorbed dose levels. In the experiments, the gamma transmission technique was utilized to investigate the gamma attenuation properties of non-irradiated and irradiated CIGS thin films at different thicknesses against Cs-137 (with 0,662 MeV) and Co-60 (with ∼1,25 MeV) gamma radioisotope sources. The irradiation process and the increase of thickness of CIGS thin films caused a higher linear attenuation coefficient, higher absorption and improvement in electrical conductivity. These results demonstrate the suitability of these materials for solar cell applications in aerospace technology, especially for high-altitude flight operations.