Comparison of Dual-Stack Dielectric Field Plates on β-Ga2O3 Schottky Rectifiers

Abstract

The effects of bilayer field plates with various dielectric (SiO2/SiNx, Al2O3/ SiNx, HfO2/ SiNx) on Ga2O3 Schottky rectifier performance were investigated. The rectifiers were fabricated on 10 μm thick, Si doped (n = 2.8 × 1016 cm−3) β-Ga2O3 epitaxial layers grown by hydride vapor phase epitaxy on Ga2O3 Sn-doped substrates (n = 4.8 × 1018 cm−3) grown by edge-defined, film-fed growth. Temperature-dependent forward current-voltage characteristics were used to extract the average Schottky barrier height of 1.14 eV ± 0.03 eV for Ni, average ideality factor of 1.02 ± 0.02, and the Richardson's constant of 48.1 A/cm2K2. The reverse breakdown and leakage current were the two characteristics predominantly affected by the field plate dielectrics. The highest reverse breakdown reached was 730 V for rectifiers with Al2O3/ SiNx, which was significantly higher than 562 V and 401 V for rectifiers with SiO2/ SiNx and HfO2/ SiNx, respectively. The on-resistance ranged from 3.8-5.0 × 10−3 Ω-cm2, which was dependent on diode size, with diameters from 50 to 200 μm. This led to a power figure-of-merit (VB2/RON) of 140 MW-cm2. Design of the field plate is crucial in determining where reverse breakdown occurs.