Depletion-mode metal-oxide-semiconductor field effect transistors (MOSFETs) with GaAs planar nanowire (NW) channels are successfully demonstrated. The Si-doped planar GaAs NWs are grown in a selective lateral epitaxy manner via Au-assisted vapor-liquid-solid (VLS) mechanism. A SiO2 interlayer between the multi-faceted NW and Al2O3 high-k dielectric formed by atomic layer deposition (ALD) improves the NW MOSFET performance. (C) 2013 Elsevier Ltd. All rights reserved.