Diodes 1: Vertical geometry Ga2O3 rectifiers

Abstract

There is increasing interest in Schottky rectifiers made on wide bandgap semiconductors because of their fast switching speed, which is important for improving the efficiency of inductive motor controllers and power supplies, as well as their low forward voltage drop and high-temperature operability. The advantage of simple Schottky rectifiers over p-n diodes is the shorter switching times due to the absence of minority carriers. This, however, leads to higher on-state resistance (RON) values than in p-i-n rectifiers. The availability of a wider bandgap than Si improves the rectifier performance, with lower on-state resistance at a given reverse voltage. Both GaN and SiC power Schottky diodes have demonstrated shorter turn-on delays than comparable Si devices. Recently, vertical geometry rectifiers fabricated on thick epitaxial layers of β-Ga2O3 on conducting substrates grown by edge-defined film-fed growth (EFG) have shown promising performance in terms of high reverse breakdown voltage (VB > 1 kV) and low RON, leading to good power figure-of-merits (VB2/RON) Electrical breakdown caused by impact ionization process will preferentially occur at the contact periphery if the maximum electric field in these areas is not reduced by proper edge termination design. This chapter summarizes recent advances in the design and implementation of Ga2O3 vertical geometry rectifiers.