Low on-resistance GaN pin rectifiers grown on 6H-SiC substrates

Abstract

Low on-resistance gallium nitride pin rectifiers grown by metal organic chemical vapour deposition on n-type 6H-SiC substrates are reported. The diode structures consist of an n + -GaN layer grown on the substrate, followed by a 2.5 mum unintentionally doped i-GaN layer, and a p-type GaN layer capped with a p ++ -GaN contact layer. The mesa-structure pin diodes exhibited a blocking voltage as large as V r ~-500 V, at a reverse current density of I r ~1 A/cm 2 . The on-resistance is 2.3 mOmega middot cm 2 for an 80 mum mesa diameter circular device. This yields a power figure of merit value of 108.69 MW/cm 2 . The on-resistance and the figure of merit values are believed to be the best reported for vertical mesa-geometry GaN pin rectifiers grown on 6H-SiC substrates with comparable i-layer thickness