Identification of swift heavy ion induced defects in Pt/n-GaN Schottky diodes by in-situ deep level transient spectroscopy

Abstract

In-situ measurements such as deep level transient spectroscopy (DLTS) provide reliable information for the identification of defects in electronic devices. For GaN-based devices exposed to swift heavy ion (SHI) irradiation, in situ DLTS investigations are not reported. The defect characterization of irradiated devices has significant relevance in the reliability testing of devices for space applications, detectors for high energy physics experiments, nuclear radiation environments near reactors and for device engineers to design better and high-performance electronic components. The present work reports on the identification of defects by employing in situ DLTS in Pt/n-GaN Schottky devices before and after SHI irradiation by 200 MeV 107Ag14+ ions at various fluences in the range of 1 × 1010 to 1 × 1011 ions cm−2. For pristine or un-irradiated diodes, trap levels at 0.173, 0.504, 0.283 and 1.012 eV below the conduction edge are observed which are reported as growth-related defects in GaN. The ion beam introduces more electron and hole traps in the bandgap. A significant increase in interface state density was instigated by irradiation which practically pinned the Schottky barrier height at 0.73 eV at an experimental time scale. The origin of these defects was compared and discussed based on literature.