Vertical Ga2O3 Schottky Barrier Diodes with Guard Ring Formed by Nitrogen-Ion Implantation

A guard ring (GR) formed by nitrogen-ion implantation doping was employed to improve the breakdown voltage $(V_{\mathrm{br}})$ of vertical Ga 2 O 3 Schottky barrier diodes (SBDs) by eliminating electric field concentration at the edges of anode and field-plate (FP) electrodes. Four types of vertical SBD structures with (a) neither a GR nor a FP, (b) a GR, (c) a FP, and (d) both a GR and a FP were fabricated on the same substrate. The SBDs with a GR [structures (b) and (d)] showed larger $V_{\mathrm{br}}$ values than their GR-free counterparts [structures (a) and (c)], implying that the GR successfully redistributed the peak electric field at the anode and/or FP edges. Considering the trade-off relationship between $V_{\mathrm{br}}$ and specific on-resistance $(R_{\mathrm{on}})$ , a $V_{\mathrm{br}}/R_{\mathrm{on}}$ combination of $1.43\ \mathrm{kV}/4.7\ \mathrm{m}\Omega \mathrm{cm}^{2}$ for the GR/FP-SBD corresponds to one of the best balanced data for Ga 2 O 3 SBDs.