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

A guard ring (GR) was employed to improve the breakdown voltage ( ${V}_{\text {br}}$ ) of vertical Ga ₂ O ₃ Schottky barrier diodes (SBDs) with or without a field-plate (FP) by eliminating electric field concentration at the edges of anode and FP electrodes. The GR structure was formed by nitrogen (N)-ion implantation. Four types of vertical SBD structures with: 1) neither a GR nor a FP; 2) a GR; 3) a FP; and 4) both a GR and a FP were fabricated on the same substrate. The SBDs with a GR [structures 2) and 4)] showed larger ${V}_{\text {br}}$ values than their GR-free counterparts [structures 1) and 3)]. Considering the trade-off relationship between ${V}_{\text {br}}$ and specific on-resistance ( ${R}_{\text {on}}$ ), a ${V}_{\text {br}}/{R}_{\text {on}}$ combination of 1.43 kV/ $4.7~\text {m}\Omega \cdot \text {cm}^{2}$ for the GR/FP-SBD corresponds to one of the best balanced data for Ga ₂ O ₃ SBDs.