Reliability Enhancement of a 2.2 kV β -Ga 2 O 3 Schottky Barrier Diode With Junction Termination Extension Under High-Temperature Storage Stress

Beta-gallium oxide ($\beta $-Ga2O3) power diodes have the potential in applications at high-temperature and high-voltage environments. The Nickel oxide (NiO)-based junction termination extension (JTE) can prevent the diodes’ premature breakdown, fully leveraging the high${E} _{\text {C}}$of$\beta $-Ga2O3. However, the reliability of$\beta $-Ga2O3Schottky barrier diode (SBD) featuring JTE under high-temperature storage stress (HTSS) warrants attention. In this study, a HTSS test at$250~^{\circ }$C was conducted on JTE-SBD and the changes in device performance over the storage time were investigated. During the test, the turn-on voltage (${V} _{\text {on}}$) of diodes increased from 0.90 to 1.10 V, while the breakdown voltage (BV) showed a phenomenon of first increasing and then decreasing. The$C$–$V$measurements shows that the carrier concentration (${N} _{\text {A}}$) of NiO initially decreases and subsequently increases, leading to the variations of the peak electric field. To enhance the device reliability, an oxygen annealing process has been proposed. By this approach, the${V} _{\text {on}}$of JTE-SBD only increased 0.10 V during the test. Due to the lower and more stable${N} _{\text {A}}$of NiO, the average BV of the annealed JTE-SBD maintained 2231 V even after 124h HTSS. Finally, X-ray photoelectron spectroscopy (XPS) spectra illustrate the reasons for the changes of${N} _{\text {A}}$of NiO. This study enhances the understanding of the reliability of$\beta $-Ga2O3and NiO, providing effective strategy for improving the stability of NiO/$\beta $-Ga2O3JTE-SBD.