Mitigating Plasma Etch-Induced Negative Charge Trapping in 2.7 kV β-Ga ₂ O ₃ (001) Trench Schottky Barrier Diodes Using H ₃ PO ₄ Treatment

High Resolution Image Download MS PowerPoint Slide Stable β-Ga 2 O 3 (001) trench Schottky barrier diodes (TSBDs) with a Baliga’s figure-of-merit (BFOM) of 0.7 GW cm –2 were demonstrated by reducing the Al 2 O 3 /Ga 2 O 3 interface state trap density using a H 3 PO 4 surface treatment during device fabrication. TSBDs with fins oriented along different directions have been studied, wherein devices with [010] fin orientation exhibited a low specific on-resistance ( R on,sp ) of 11 mΩ cm 2 and a breakdown voltage ( V br ) of up to 2.7 kV with H 3 PO 4 treatment. Reliability testing using sequential voltage stress up to a reverse bias of −1.2 kV showed a degradation in R on,sp by 20% in untreated devices but only by 9% in those with the H 3 PO 4 surface treatment. TCAD simulations confirm that the H 3 PO 4 treatment mitigates the density of negative interface charges, highlighting the effectiveness of the acid treatment in controlling defect-mediated instabilities. Furthermore, high-temperature bias stress tests demonstrated that [010]-oriented TSBDs achieved superior thermal and electrical stability after the treatment, eliminating the 10% R on,sp increase observed in untreated devices. These results establish H 3 PO 4 surface treatment as an effective strategy for enhancing the robustness of β-Ga 2 O 3 power devices under combined thermal and electrical stress.