Combined thermionic emission and tunneling mechanisms for the analysis of the leakage current for Ga2O3 Schottky barrier diodes

A new analysis method of reverse leakage current for β-Ga2O3 Schottky barrier diodes is performed by using two models: bias dependence and no bias dependence of barrier height. The method incorporates both the current induced by the tunneling of carriers through the Schottky barrier and the current induced by the thermionic emission of carriers across the metal–semiconductor interface. The experimental reverse transition voltage between thermionic emission and tunneling process can be determined from the intersection of the two components that were separated from the total current. Below the reverse transition voltage, the thermionic emission current dominates, and above it, the tunneling current dominates, while near the reverse transition voltage, neither tunneling nor thermionic emission accurately describes the conduction process because the both currents have the same order of magnitude; therefore, the both mechanisms must be combined together. The experimental reverse transition voltage (bias-dependent model) increases for low and high temperatures and decreases at intermediate temperatures for β-Ga2O3 Schottky barrier diodes. The bias dependence of the barrier height model shows that the barrier height is strongly dependent (increases) on the reverse bias, in particular at low temperatures and low reverse bias. This model can explain the discrepancy between the experimental characteristics and those calculated by no bias dependence of barrier height model.