Gamma-irradiation-induced surface defect engineering in In2O3 thin films: correlating structure, optics, and electrical transport
摘要
Indium oxide (In2O3) is a technologically important transparent conducting oxide that is widely employed in optoelectronic devices, gas sensors, and energy-related applications. In this study, we systematically investigated the impact of gamma (γ) irradiation on the structural, optical, and electrical integrity of In2O3 thin films. The films were fabricated on SiO2/Si substrates using the RF sputtering technique. The films were exposed to controlled gamma doses (0, 50, 100, and 150 kGy) to induce irradiation-driven defect modulation without altering their chemical composition. X-ray diffraction analysis revealed dose-dependent changes in crystallinity, crystallite size (19.28–15.74 nm), and lattice strain, indicating a radiation-induced rearrangement of the In–O framework. The electrical properties, studied via Hall effect measurements, revealed that the formation of oxygen vacancies acting as shallow donors led to lower resistivity (0.000238–0.000202 Ω cm) and decreased carrier concentration (2 × 1021−1.51 × 1021 cm−3) and mobility (14.39–19.05 cm2 V−1 s−1) based on electrical measurement results. Optical properties measured by UV–Visible spectroscopy showed that light transmission increased, while a slight direct bandgap energy shifted from 3.92 eV in pristine In2O3 to 3.51 eV after a 150 kGy radiation dose. The pristine and gamma-irradiated films exhibit an emission peak with an average luminance at 440 nm, 424 nm, 429 nm, and 433 nm, attributed to oxygen vacancy states, respectively. This study provides valuable insights into radiation-matter interactions in oxide semiconductors and highlights the potential of gamma-irradiated In2O3 for advanced applications in transparent electronics, radiation-hard devices, and sensing technologies.