▎ 摘　　要

A chemically doped graphene-based three-branch nanojunction device is fabricated on a SiO2/p-Si substrate, and its nonlinear operation is characterized at room temperature (RT). By polyethyleneimine doping, the fabricated device shows improved field effect mobility of 14 800 and 16 100 cm(2)/Vs for electron and holes, respectively. The device clearly exhibits nonlinearity in voltage transfer curves at RT. The curvature of the transfer curve can be controlled by using the back gate voltage, and its polarity abruptly switches near the Dirac point because of the carrier type change. The observed behaviour can be quantitatively explained in terms of the difference in the amounts of gate-induced carriers in the two input branches. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4711035]