Abstract

We proposed a new AlGaN/GaN high-electron-mobility transistor using a trench structure for high-voltage switching applications. The proposed trench structure was designed for the use at the gate edge, which improved the gate leakage current and breakdown voltage. We considered that the thickness of the AlGaN barrier was related to the polarization, surface-state density and leakage current. The surface states at the gate edge were controlled by etching the AlGaN barrier by 22 nm. The gate leakage current of the proposed device was 40 ?A/mm while that of a conventional device was 201 ?A/mm with a reverse gate-drain voltage of 100 V. The suppressed gate leakage current may have been caused by the decrease in the surface states at the gate edge. The breakdown voltage of the proposed device was 762 V while that of the conventional device without a trench structure was 120 V. The forward drain current and transconductance of the proposed device were decreased slightly because the channel resistance was increased in the trench region. The results of this study suggest that the trench structure improves the off-state characteristics of GaN power switches.

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