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

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 (Von) 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 Von of 0.35 V, a specific on-resistance (Ron,sp) of 6.25 mΩ•cm², and a current density of 598 A/cm² at 6 V. Under reverse bias, the enhanced depletion effect at the Ni/Ga2O3 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 (Dit) of the WFM-Fin-SBD is situated between those of the Ti-SBD and the Ni-SBD. The slightly elevated Dit 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.