Double drift layers to minimize on-resistance in 2.7-kV β-Ga₂O₃ (001) vertical trench Schottky barrier diodes

Improved specific on-resistance (Ron,sp) in beta-gallium oxide (β-Ga₂O₃) trench Schottky barrier diodes (TSBDs) is achieved without the usual trade-off of reduced breakdown voltage, enabled through the use of a double drift layer (DDL) TSBD architecture; this incorporates a Si-doped drift layer atop an unintentionally doped (UID) drift region. DDL TSBDs show a 46% reduction in R_on,sp compared to single-UID drift layer TSBDs, while maintaining a similar V_br of 2.6–2.7 kV. As a result, the DDL TSBD design enhances Baliga's figure-of-merit from 481 MW/cm² for conventional TSBDs to 959 MW/cm², marking a twofold improvement. Silvaco TCAD simulations further confirm that both structures exhibit similar dominant peak electric fields at the trench corners, consistent with their comparable breakdown voltages. While reducing fin width in TSBDs enhances V_br because of an improved reduced surface field effect, we demonstrate that this effect is significantly amplified in DDL TSBDs, enabling a substantial shift in the conventional R_on,sp–V_br trajectory.