Normally-off AlGaN/GaN FinFETs have been fabricated by fully covering the nanochannel region with a metal gate. Removing the source/drain extensions (gate underlap regions) greatly decreases the access resistance of the device, which results in an order of magnitude higher on-current and transconductance. As compared with earlier HEMT FinFETs, where the nanochannel is only partially covered by the gate, the carrier trapping at the surface and in the buffer layer is effectively reduced, improving the gate and the drain lags. (C) 2013 Elsevier Ltd. All rights reserved.