Experimental study of Ni/TiO2/β-Ga2O3 metal–dielectric–semiconductor diodes using p-NiO junction termination extension

This work demonstrates TiO2/β-Ga2O3 metal–dielectric–semiconductor (MDS) diodes with an average breakdown field beyond the material limits of SiC and GaN. These MDS diodes have lower conduction losses and higher breakdown voltage (Vbk) than the cofabricated Schottky barrier diodes (SBDs), simultaneously improving both on- and off-state parameters that are typically in competition with each other. With further optimized field management using p-NiO guard rings (GRs), the Ni/TiO2/β-Ga2O3 MDS diodes present a path to realistically utilize the high critical field of Ga2O3 without large forward conduction losses from a high-barrier junction. MDS diodes showed a lower Von (0.8 V) than the SBDs (1.1 V) from linear extrapolation of the current density-voltage (J-V) curve. The MDS diode had higher Vbk of 1190 V (3.0 MV/cm) compared to 685 V (2.3 MV/cm) for the SBD, and the MDS diode with the p-NiO guard ring saw further improvement with Vbk of 1776 V (3.7 MV/cm) compared to 826 V (2.5 MV/cm) for GR SBD. The BFOM (Vbk2/Ron,sp) of 518 MW/cm2 for the GR HJD is competitive with other literature results. A new figure of merit that includes the impact of turn on voltage is also proposed and demonstrated in this paper, which highlights how diodes perform in a practical high-power operation. This full paper is derived from the proceeding abstract of Willams et al. [IEEE Device Research Conference, Santa Barbara, CA, 25-28 June 2023 (IEEE, New York, 2023)].