Demonstration of enhanced electrical and thermal stability in NiO/Ga2O3 heterojunction diode adopting Li-doped p -type NiO

Constructing p-type nickel oxide (NiO)/n-type gallium oxide (Ga2O3) heterojunction diodes (HJDs) represents a promising strategy to enhance the performance of beta-phase Ga2O3 power diodes, yet their poor electrical and thermal stability remains a critical bottleneck that limits practical applications. This work demonstrates a NiO/Ga2O3 HJD with enhanced electrical and thermal stability enabled by lithium (Li)-doped p-type NiO. In Li-doped NiO films, Ni3+, as the dominant hole source, originates from the stable substitutional impurities (LiNi) rather than the metastable nickel vacancies (VNi) present in undoped NiO. This mechanism stabilizes hole concentration in Li-doped NiO, thus endowing the HJD with excellent electrical and thermal stability. The experimental results show that the grown Li-doped NiO film exhibits excellent crystalline quality, uniform Li doping distribution, and negligible resistivity variations after 700 °C thermal stress up to 60 min. Moreover, for the Li-doped NiO/Ga2O3 HJD, its forward and reverse J–V characteristics exhibit negligible degradation after 10 ks of forward electrical stress and 175 °C ambient thermal stress, demonstrating outstanding electrical and thermal stability of the device.