Engineering oxide interfaces with defined electronic band structures is of vital importance for designing all-oxide devices with controllable multifunctionality and improved performance. Here, we report the band alignment, band bending, and transport mechanism in the NiO/ $\beta $ -Ga₂O₃ p-n heterojunction (HJ) which exhibits high performances with a rectification ratio over 10¹¹, a turn-on voltage of 1.87 V and specific ON-resistance of 10.2 $\text{m}\Omega \cdot $ cm². A type-II band alignment is identified at NiO/ $\beta $ -Ga₂O₃ HJs with a valence band offset of 3.60 eV and a conduction band offset of 2.68 eV, respectively, determined from the depth-profiled X-ray photoelectron spectroscopic analysis. Besides band edge discontinuity, an additional built-in potential of 0.78 V is observed at the interface due to the charge transfer across the p-n-junction. In comparison, the NiO/ $\beta $ -Ga₂O₃ p-n HJ has lower leakage current and higher breakdown voltage than that of the Ni/Ga₂O₃ Schottky barrier diode. Capacitance–frequency analysis indicates the presence of interfacial states, and interface recombination is the dominant transport mechanism. The type-II NiO/Ga₂O₃ HJ provides favorable energetics for facile separation and transportation of photogenerated electrons and holes, which is important for all-oxide devices that require bipolar operation and power devices with higher conversion efficiencies.

中文翻译：

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NiO/β-Ga₂O₃ II 型 pn 异质结中的能带对准和界面复合

具有定义电子能带结构的工程氧化物界面对于设计具有可控多功能性和改进性能的全氧化物器件至关重要。在这里，我们报告了 NiO/ $\beta $ -Ga ₂ O ₃ pn 异质结 (HJ)，具有超过 10 ¹¹的整流比、1.87 V 的导通电压和 10.2 的比导通电阻的高性能 $\text{m}\Omega \cdot $ 厘米²。在 NiO/ $\beta $ -Ga ₂ O ₃ HJs 分别具有 3.60 eV 的价带偏移和 2.68 eV 的导带偏移，由深度剖面 X 射线光电子光谱分析确定。除了带边不连续性之外，由于跨 pn 结的电荷转移，在界面处观察到额外的 0.78 V 内置电位。相比之下，NiO/ $\beta $ -Ga ₂ O ₃ pn HJ 比Ni/Ga ₂ O ₃肖特基势垒二极管具有更低的漏电流和更高的击穿电压。电容-频率分析表明存在界面态，界面复合是主要的传输机制。II型NiO/Ga ₂ O ₃ HJ为光生电子和空穴的轻松分离和传输提供了有利的能量，这对于需要双极操作的全氧化物器件和具有更高转换效率的功率器件很重要。