Barrier Height Stability and Reverse Leakage Mechanisms in Ni/Ga2O3 (001) Schottky Barrier Diodes

Ga
₂
O
₃
Schottky barrier diodes (SBDs) have shown promising performance as power rectifiers recently [1]-[3], showcasing the fast-improving material quality as well as the touted high electric field strength (6-8 MV/cm). In an SBD, the barrier height (qφB) largely determines the turn-on voltage and the reverse leakage current. Previous studies on the barrier height of different metal contacts on Ga
₂
O
₃
indicate a certain level of Fermi-level pinning [4], [5], likely due to interface-trap states. Under different temperature (T) or biasing conditions, the filling of those trap states could be altered and thus the barrier height could be unstable, as evidenced in previous studies [6]. For Ga
₂
O
₃
grown by halide vapor phase deposition (HVPE), a chemical-mechanical polishing (CMP) process is used to flatten the surface. In this work, we examine the barrier height stability of Ni/Ga
₂
O
₃
SBDs fabricated on the CMP-ed surface via repeated and temperature-dependent I-V measurements. We found that post metallization annealing (PMA) improves the barrier height stability. In addition, the reverse leakage mechanisms of the non-field-plated SBDs have been identified.