High Temperature Charge Transport Mechanisms in p-NiO/β-Ga 2 O 3 Heterojunction Diodes

Abstract In this work, we comprehensively study the charge transport mechanisms at high temperatures in p-NiO/β-Ga 2 O 3 heterojunction diodes by combining the capacitance-voltage and current-voltage sweepings, and the low-frequency noise analysis. The capacitance exhibits a significant frequency dispersion, suggesting the presence of deep-level defect states, which compensate donor impurities and reduce effective doping density. The saturation current has an activation energy of ~223 meV, implying an incomplete ionization of the defect states at room temperature. The forward current features two distinct power-law dependences, indicating a dual-defect space-charge-limited current. The reverse leakage current cannot be described by the defect-related Frekel-Poole emission or Fowler-Nordheim tunneling mechanisms. The noise spectra at reverse biases maintain a stable exponent of γ ~2, demonstrating that the generation current should be dominant.