Neutron irradiation induced transmuted Ga-doping of ZnO thin films: Structural and opto-electronic investigations

Metal oxide nanoparticles, particularly zinc oxide (ZnO) thin films, have significant applications in photocatalysis, non-volatile memories, resistive switching, energy conversion, and many more. This study examines the effects of neutron irradiation on ZnO thin films synthesized via a sol-gel and spin coating technique, subsequently annealed at 450 °C. The films are exposed to neutron radiation of various fluence rates. One of the major effects of neutron irradiation is the transmutation of zinc (Zn) into gallium (Ga), resulting in a Ga-doped ZnO thin film. Scanning electron microscopy (SEM) reveals morphological changes, including forming nano-scale structures on the surface, post-irradiation. Energy dispersive X-ray analysis (EDAX) identifies the transmutation of Zn to Ga. X-ray diffraction indicates a shift in the peaks due to radiation-induced defects. Optical studies show a blue shift in absorption spectra and an increase in bandgap from 3.1 eV to 3.2 eV after irradiation. Photoluminescence spectra exhibit intensified defect-related emissions. Electrical measurements via I-V and Hall techniques reveal reduced current and carrier concentrations with transmuted Ga-doped ZnO thin film. These findings highlight the significant impact of neutron irradiation on the structural, optical, and electrical properties of ZnO thin films, providing insights into their behaviour under space-like conditions.