Physical mechanism of the work function modulated fin-channel β -Ga ₂ O ₃ based diode with a low turn-on voltage

Abstract This paper presents a novel work function modulated Fin-channel schottky barrier diode (WFM-Fin-SBD) with optimized electrical characteristics. The architecture incorporates Ti as the Schottky metal on the Fin top surface to reduce the turn-on voltage ( V _on ) and mitigate forward conduction loss. Simultaneously, Ni is selectively deposited on the Fin sidewalls and trenches bottom. This configuration ensures effective carrier depletion within the fin channel under both zero-bias and reverse-bias conditions, thereby suppressing reverse leakage current and enhancing the breakdown voltage. As a result, the WFM-Fin-SBD achieves superior performance metrics, including a low V _on of 0.35 V, a specific on-resistance ( R _on,sp ) of 6.25 mΩ·cm ² , and a current density of 598 A cm ⁻² at 6 V. Under reverse bias, the enhanced depletion effect at the Ni/Ga ₂ O ₃ interface effectively pinches off the conductive channel, which suppresses the leakage current and enables a breakdown voltage of −241 V, which is approximately 5.5 times that of conventional Ti-SBDs. Furthermore, frequency-dependent conductance measurements reveal that the interface trap density ( D _it ) of the WFM-Fin-SBD is situated between those of the Ti-SBD and the Ni-SBD. The slightly elevated D _it compared to the Ni-SBD is mainly attributed to the presence of Ti at the Fin top. Meanwhile, TCAD simulations elucidate the underlying physical mechanisms. The proposed WFM-Fin-SBD demonstrates superior performance, positioning it as a promising candidate for high-efficiency power electronics.