Effect of 50MeV Li³⁺ ion irradiation on structural, optical and electrical properties of amorphous Se₉₅Zn₅ thin films

Present work focuses on the effect of swift heavy ion (SHI) irradiation of 50MeV Li³⁺ ions by varying the fluencies in the range of 1×10¹² to 5×10¹³ ions/cm² on the morphological, structural, optical and electrical properties of amorphous Se₉₅Zn₅ thin films. Thin films of ~250nm thickness were deposited on cleaned glass substrates by thermal evaporation technique. X-ray diffraction (XRD) analysis shows the pristine thin film of Se₉₅Zn₅ growsin hexagonal phase structure. Also it was found that the small peak observed in XRD spectra vanishes after SHI irradiation indicates the defects of the material increases. The optical parameters: absorption coefficient (α), extinction coefficient (K), refractive index (n) optical band gap (E_g) and Urbach's energy (E_U) are determined from optical absorption spectra data measured from spectrophotometry in the wavelength range 200-1000nm. It was found that the values of absorption coefficient, refractive index and extinction coefficient increases while the value optical band gap decreases with the increase of ion fluence. This post irradiation change in the optical parameters was interpreted in terms of bond distribution model. Electrical properties such as dc conductivity and temperature dependent photoconductivity of investigated thin films were carried out in the temperature range 309-370 K. Analysis of data shows activation energy of dark current is greater as compared to activation energy photocurrent. The value of activation energy decreases with the increase of ion fluence indicates that the defect density of states increases.Also it was found that the value of dc conductivity and photoconductivity increases with the increase of ion fluence