Ion-Type Irradiation Effect on Optical, Structural, and Morphological Properties of ZnO Thin Films

ZnO thin films were deposited on soda-lime glass substrates using the chemical spray pyrolysis method at a temperature of 500 ºC. After deposition, the substrate was irradiated with H+ and Ar+ ions using a 10 keV energy with a Colutron ion gun. We investigated the optical, structural, and morphological properties resulting from ion irradiation through Rutherford Backscattering Spectrometry, Ultraviolet and Visible Spectroscopy, X-ray diffraction, and Scanning Electron Microscopy. We observed a decrease in the optical band gap in the irradiated samples, attributed to the quantum confinement effect resulting from changes in the crystallite size. The diffractograms revealed diffraction peaks corresponding to the planes characteristic of the hexagonal wurtzite phase of ZnO, which indicate that the films are polycrystalline with a preferential orientation along the c-axis. We observed a decrease in the average crystallite size in the samples after ion irradiation. The morphological study reveals an increase in the average particle size after irradiation, and a change in their shape, from spherical in the pristine sample to flake-like in the irradiated samples. The sample irradiated with Ar+ ions also exhibited a bimodal distribution in particle size, which is attributed to the defects and nucleation centers created during the irradiation process.