▎ 摘　　要

We demonstrate tunable field effect properties in solid state and flexible graphene field effect devices (FEDs) fabricated using a poly(methylmethacrylate) (PMMA) and lithium fluoride (LiF) composite dielectric. Increasing the concentration of LiF in the composite dielectric increases the capacitance, which thereby reduces the operating gate voltages of FEDs significantly from 10 V to 1 V to achieve similar conductivity. Electron and hole mobility of 350 and 310 cm(2)/V at V-D = -5 V are obtained for graphene FEDs with 10% LiF concentration in the composite. Composite dielectric also enabled excellent FEDs on flexible substrates without any significant change in mobility and resistance. Flexible FEDs with only 5% and 12% variation in mobility for 300 and 750 bending are obtained. (C) 2015 Elsevier Ltd. All rights reserved.