Effect of gamma irradiation on the structural and optical properties of thin films of a-CdSe

Thermal quenching technique was used for the preparation of bulk sample of amorphous CdSe (50:50 composition) (a-CdSe) and the thin films were fabricated by thermal evaporation technique on glass substrates. The thin films of a-CdSe were irradiated by 60Co gamma-rays of different doses. XRD patterns of as-deposited and gamma irradiated thin films show phase transformation from amorphous to crystalline state after gamma irradiation. FT-IR spectrum shows strong asymmetric stretch and indicates that the bond strength increases after gamma irradiation. PL study confirms the defect concentration decreases and also supports the change in optical properties occurs due to gamma irradiation. The optical characterization of as deposited and gamma-ray irradiated thin films of CdSe were carried out by using UV-vis-spectrophotometer. It was found that the value of optical band gap increases and other optical parameters like extinction co-efficient (K), refractive index (n), Urbach's energy (Eu) and absorption co-efficient (α) changes accordingly.