We have synthesized InAs nanowires (NWs) by selective area molecular beam epitaxy (SA-MBE) on GaAs masked substrates. In particular, we have obtained in-plane-oriented NWs on the (110) plane, and then directly applied the NWs to planar nanowire field-effect transistors (NWFETs) using conventional electron beam lithography without a NW dispersion process. We have measured output and transfer characteristics of the NWFETs at room temperature, and obtained a current swing but no turning off, and a field-effect mobility peak of 150 cm(2)/V-s. We have also observed almost no temperature influence on field-effect mobility between 2 K and 300 K, suggesting a high-dense surface accumulation layer even at low temperatures. (c) 2012 Elsevier B.V. All rights reserved.