Vertical heterojunction field‐effect transistors utilizing re‐grown AlGaN/GaN two‐dimensional electron gas channels on GaN substrates

Abstract

Abstract Vertical heterojunction field‐effect transistors (VHFETs) utilizing re‐grown AlGaN/GaN two‐dimensional electron gas (2DEG) channels on free‐standing GaN substrates have been developed. The VHFETs exhibited a specific on‐resistance (RonA) of 7.6 mΩcm 2 at a threshold voltage (V th ) of ‐1.1 V and a breakdown voltage (VB) of 672 V. The breakdown voltage and the figure of merit (VB 2 /RonA) are the highest among those of the GaN‐based vertical transistors ever reported. It was demonstrated that the threshold voltage can be controlled by the thickness of AlGaN layers and Al concentration. A normally‐off operation was achieved with a 10‐nm‐thick Al 0.2 Ga 0.8 N layer. The possibility that VHFET with smaller current collapse phenomena than planar HEMT was revealed (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)