Novel Vertical Heterojunction Field-Effect Transistors with Re-grown AlGaN/GaN Two-Dimensional Electron Gas Channels on GaN Substrates

摘要

Novel vertical heterojunction field-effect transistors (VHFETs) with re-grown AIGaN/GaN two-dimensional electron gas (2DEG) channels on freestanding GaN substrates have been developed. The VHFETs exhibited a specific on-resistance (R_(on)A) of 7.6 mΩ cm~2 at a threshold voltage (V_(TH)) of -1.1 V and a breakdown voltage (V_B) of 672 V. The breakdown voltage and the figure of merit (V_B~2/R_(on)A) 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 AIGaN layers and a normally-off operation was achieved with a 10-nm-thick Al_(0.2)Ga_(0.8)N layer.