High-k dielectric integration to improve breakdown characteristics of β-Ga₂O₃ Schottky diode

In this work, we have utilized a high-k dielectric material, bismuth zinc niobium oxide (BZN), to fabricate metal-insulator-semiconductor (MIS) heterostructure Schottky barrier diodes (SBDs) on $\beta-\mathrm{Ga}_{2}\mathrm{O}_{3}$. This integration significantly increased the barrier height (SBH) by nearly 0.22 eV, resulting in a two-fold improvement in breakdown voltage $(V_{BR})$, with minimal impact on specific on-resistance $(\mathrm{R}_{on,sp})$. The devices displayed excellent current-voltage characteristics with close-to-unity ideality factors and high $I_{on}/I_{off} \gt 10^{10}$. Specifically, the absolute $V_{BR}$ value increased from 238.5 V for the metal-semiconductor (MS) SBD to 500 V for the MIS SBD. This showed the effectiveness of BZN (k ~ 210) in increasing the breakdown electric field in $\beta-\mathrm{Ga}_{2}\mathrm{O}_{3}$ approaching its breakdown field limit under reverse bias.