III-V nitride semiconductor device, and protection element and power conversion apparatus using the same

摘要

A GaN-based Schottky diode includes a sapphire substrate on which are formed a GaN buffer layer, an n+-type GaN layer, and an n-type GaN layer that has a surface portion thereof shaped to form a protrusion having an upper face with which a Ti electrode forms a Schottky junction and a side face with which a Pt electrode forms a Schottky junction through an Al0.2Ga0.8N layer. A cathode electrode constituted by a TaSi layer forms an ohmic junction with the n+-type GaN layer. The Ti and Pt electrodes constitute a combined anode electrode contributing to increasing a withstand voltage of and decreasing an on-voltage of the Schottky diode.