In this paper, we discussed the effect of field plate dielectric materials such as silicon dioxide (SiO2), aluminum oxide (Al2O3), and hafnium oxide (HfO2) on the breakdown characteristics of β-Ga2O3 Schottky barrier diodes (SBDs). The breakdown voltage (BV) of the SBDs with a field plate was higher than that of SBDs without a field plate. The higher dielectric constant of HfO2 contributed to the superior reduction in electric field concentration at the Schottky junction edge from 5.4 to 2.4 MV/cm. The SBDs with HfO2 field plate showed the highest BV of 720 V, and constant specific on-resistance (Ron,sp) of 5.6 mΩ·㎠, resulting in the highest Baliga’s figure-of-merit (BFOM) of 92.0 MW/㎠. We also investigated the effect of dielectric thickness and field plate length on BV.
