%AXia, Xinyi%ALi, Jian-Sian%AChiang, Chao-Ching%AYoo, Timothy%ARen, Fan%AKim, Honggyu%APearton, S.%BJournal Name: Journal of Vacuum Science & Technology A; Journal Volume: 40; Journal Issue: 5 %D2022%I %JJournal Name: Journal of Vacuum Science & Technology A; Journal Volume: 40; Journal Issue: 5 %K %MOSTI ID: 10344198 %PMedium: X %TThermal stability of band offsets of NiO/β-GaN %XNiO is a promising alternative to p-GaN as a hole injection layer for normally-off lateral transistors or low on-resistance vertical heterojunction rectifiers. The valence band offsets of sputtered NiO on c-plane, vertical geometry homoepitaxial GaN structures were measured by x-ray photoelectron spectroscopy as a function of annealing temperatures to 600 °C. This allowed determination of the band alignment from the measured bandgap of NiO. This alignment was type II, staggered gap for both as-deposited and annealed samples. For as-deposited heterojunction, ΔE V  = 2.89 eV and ΔE C  = −2.39 eV, while for all the annealed samples, ΔE V values were in the range of 3.2–3.4 eV and ΔE C values were in the range of −(2.87–3.05) eV. The bandgap of NiO was reduced from 3.90 eV as-deposited to 3.72 eV after 600 °C annealing, which accounts for much of the absolute change in ΔE V  − ΔE C . At least some of the spread in reported band offsets for the NiO/GaN system may arise from differences in their thermal history. %0Journal Article