Leakage current suppression and breakdown voltage enhancement in GaN-on-GaN vertical Schottky barrier diodes enabled by oxidized platinum as Schottky contact metal

Abstract

In this work, the oxidized metal PtO x was employed as the Schottky contact metal in the fabrication of gallium nitride (GaN)-on-GaN vertical Schottky barrier diodes (SBDs). Compared with the GaN SBD with just Pt Schottky anode, the Pt/PtO x /Pt-GaN SBDs exhibited a substantial reduction in reverse leakage current density from 5.2 × 10−6 A cm−2 to 5.6 × 10−9 A cm−2 (@ −50 V) and a large rise in the breakdown voltage () from 152 to 368 V, as well as maintaining the similar on-state characteristics in terms of turn-on voltage and on resistance. The temperature-dependent current–voltage characteristics of the fabricated devices further revealed that the Pt/PtO x /Pt-GaN SBDs possessed a higher Schottky barrier height and better high-temperature stability. Such an improvement should be attributed to the electric dipole effect in the PtO x layer. Moreover, the additional thin Pt layer between PtO x and GaN almost have no influence on the electric dipole effect of PtO x but can effectively protect the GaN surface from plasma damage and oxidation during the PtO x deposition. We believe that the proposed Pt/PtO x /Pt-GaN Schottky contact scheme provides a straightforward and effective strategy to develop next-generation GaN power electronic devices.