Electron beam induced modifications of bismuth sulphide (Bi2S3) thin films: Structural and optical properties

Thin films of Bi2S3 prepared by electrodeposition method are subjected to electron beam irradiation for different doses from 0 to 100 kGy in steps of 20 kGy in air at room temperature. The changes in structural, surface morphological and optical properties that occurred before and after irradiation in Bi2S3 thin films are studied using X-ray diffraction, scanning electron microscopy and UV–vis spectroscopy. It is shown that electron irradiation can be used as a tool to decrease the crystallite size of the irradiated films from 418 to 285 Å as the dose varies from 20 to 100 kGy. The decrease in crystallinity of the films leading to the band gap energy of the films get blue shifted from unirradiated films. These results are explained in the light of thermal spike model.