▎ 摘　　要

Graphene field-effect transistors (GFETs) were fabricated by aligning the dispersed graphene flakes precisely with the pre-defined Ti/Au electrodes on SiO2/Si substrate by using a non-uniform electric field, where a large density of the graphene flakes was prepared by sonicating three-dimensional (3-D) graphene foam. Effects of ultra-violet (UV) illuminations and vacuum annealing on the electrical characteristics of the processed GFETs were investigated. A remarkable increase in conductivity and carrier mobility was observed after vacuum annealing at 100 degrees C, which was more effective than UV illuminations to improve the electrical performance of our GFETs. Our method to obtain the dispersed graphene flakes from 3-D graphene foam and assemble them by a dielectrophoretic force allows a reliable, scalable, and controllable fabrication of GFETs. (C) 2013 The Electrochemical Society. All rights reserved.