Surface related tunneling leakage in β-Ga2O3 (001) vertical Schottky barrier diodes

β-Ga2O3 (001) Schottky barrier diodes (SBDs) fabricated on a halide vapor phase epitaxy-grown epilayer showed anomalous reverse leakage characteristics, which could not be explained through thermionic field emission theory. A systematic investigation through the measurements and simulations of capacitance-voltage and current density-voltage characteristics suggested the presence of a thin surface layer on the epilayer with high density of oxygen vacancy states. This thin surface layer allowed the tunneling of electrons and caused anomalous reverse leakage properties (Thin surface barrier model). Annealing of the epilayer in an oxidative environment passivated the surface oxygen vacancy states and reduced the reverse leakage current enormously.