Development And Application Of Deep-Level Spectroscopy Systems For Characterizing Irradiation-Induced Traps In Gallium Nitride Schottky Diodes

Crystal defects are a natural consequence of the gallium nitride (GaN) crystal growth process and may also be introduced by exposure to radiation environments, leading to degradation of device performance. Detection of these defects are completed through various methods of characterization including Deep-Level Transient Spectroscopy (DLTS) and Deep-Level Optical Spectroscopy (DLOS). In this work, a custom DLOS measurement system was developed and validated to investigate deep-level defects in GaN Schottky diodes before and after irradiation. GaN Schottky diode structures and wafer layouts were designed based on baseline technology provided by the University of New Mexico (UNM) and modified to meet both DLOS measurement requirements and anticipated radiation conditions. The new custom DLOS system was validated using a reference GaN device. Silicon ions and electrons were used to irradiate the diodes. The extreme environment resulted in changes to electrical parameters found through IV and CV measurements indicating the diodes experienced irradiation-induced changes. DLTS revealed one known defect at 0.22 ± 0.011 eV most likely due to the crystal growth process. Results demonstrate the successful development of a DLOS system and irradiation of GaN Schottky diodes. Ultimately, future work is needed to induce more defects through different radiation conditions.