Electric field management in $\beta$-$Ga_2O_3$ vertical Schottky diodes using high-k bismuth zinc niobium oxide

Abstract

In this work, we have integrated bismuth zinc niobium oxide (BZN), a high-k dielectric material, in metal-insulator-semiconductor (MIS) and field-plated metal-semiconductor (FP-MS) Schottky barrier diodes on $\beta$-$Ga_2O_3$. This increases the breakdown voltage ($V_{BR}$) from 300 V to 600 V by redistributing the electric fields, leveraging the high permittivity of BZN (k ~210). Enhancement in Schottky barrier height, by approximately 0.14 eV for MIS and 0.28 eV for FP-MS devices, also contributes to the improved $V_{BR}$. BZN inclusion has minimal impact on specific on-resistance ($R_{on,sp}$). Additionally, the devices display excellent current-voltage characteristics with ideality factors close to unity and an on/off current ratio greater than 1010. This work presents the most significant $V_{BR}$ enhancement reported-to-date for MIS devices on $\beta$-$Ga_2O_3$ without compromising turn-on voltage and $R_{on,sp}$. A comparison of FP-MS and MIS devices shows that FP-MS outperforms MIS in terms of lower $R_{on,sp}$, higher Schottky barrier height, and improved VBR.