Guiding Principles for Trench Schottky Barrier Diodes Based on Ultrawide Bandgap Semiconductors: A Case Study in Ga2O3

Ultrawide bandgap (UWBG) semiconductors such as beta-Ga2O3 can support a much higher electric field than traditional wide bandgap semiconductors, thus promising an unprecedentedly low conduction loss. However, the maximum electric field in regular Schottky barrier diodes (SBDs) is limited due to the constraint set by the reverse leakage current. On the other hand, a trench SBD structure allows for a much higher electric field to be sustained thanks to the reduced surface field (RESURF) effect. In this article, the guiding principles for trench SBDs are investigated through a case study in Ga2O3. The advantages of trench SBDs are discussed both by quantitative analysis of the ON-state voltage drop (V-ON), as well as by a review of the state-of-the-art Ga2O3 device performance. It is found that for kilovolt-class operation, the trench SBD structure is not only preferred but arguably necessary for high-efficiency Ga2O3 rectifiers. In addition, the effects of fin/trench geometry on the specific ON-resistance and the electric-field profile are investigated. A design flow oriented toward device performance targets is presented, together with an example design of a 1375-V Ga2O3 trench SBD, showing that a V-ON (defined at 100 A/cm(2)) of below 1 V can be obtained. These results highlight the importance in harnessing the high breakdown field of UWBG semiconductors through trench SBDs for efficient power rectifiers, and provide valuable insights into the device design and optimization.