Near-ideal reverse leakage current and practical maximum electric field in β-Ga₂O₃ Schottky barrier diodes

We investigate the intrinsic reverse leakage mechanisms in Ni-based Schottky barrier diodes (SBDs) fabricated on a (⁠$2¯$01) single crystal β-Ga₂O₃ substrate, where a uniform bulk reverse leakage current has been designed and confirmed. The temperature-dependent reverse leakage characteristics are analyzed by a numerical reverse leakage model, which includes both the image-force lowering and doping effects. We found that the reverse leakage current is near-ideal and dominated by Schottky barrier tunneling throughout the entire range of the surface electric field from 0.8 MV/cm to 3.4 MV/cm. The extracted barrier height from the reverse leakage model is consistent with the values extracted from the forward current–voltage and capacitance–voltage measurements. The practical maximum electric field, defined by the maximum allowable reverse leakage current levels, is calculated as a function of the barrier height. These results suggest that it is possible to approach the intrinsic breakdown electric field in β-Ga₂O₃ SBDs, as long as a sufficiently high barrier height (∼2.2 to 3 eV) is employed.