Effects of gamma radiation on structural, optical, and electrical properties of SnO2 thin films

Abstract

Gamma irradiation at specific doses controls the material properties of thin films because of its high-ionization energy and high penetrating power. In the present work, the effects of gamma irradiation (γ-rays) on the structural, morphological, electrical, and optical properties of pulsed laser-deposited SnO2 thin films were examined. These films were exposed to γ-rays for doses of 0, 75, 100, 125, and 200 kGy. X-ray diffraction analysis reveals that the films are polycrystalline with a crystallite size of 49.27 nm and it increases with the gamma doses. While the dislocation density and the microstrain decrease, the band gap reduces from 3.8 eV to 3.4 eV with the increase in doses. Raman spectra show the presence of defects caused by gamma irradiation and the photo luminance spectra demonstrate a decrease in the peak intensities for thin films. The blue emission at 437 nm, is associated with oxygen-related defects produced during the phase formation. The Hall measurements confirm that these films are of n-type semiconductors. The I–V characteristics show a rise in conductivity linearly up to 125 kGy and a reduction at 200 kGy due to oxygen vacancies created at the higher gamma doses. The electrical conductivity of all the films increases as a function of temperature, and gamma doses as evident from the rectification behavior. This study infers that gamma rays can modify the material properties hence these films are useful as an electrode for sensing and radiation detection.