Graphene field effect transistors with optimized contact resistance for current gain

Abstract

Graphene is a promising two dimensional channel material for radio frequency field effect transistors (RF-FET)[1]. It has ambipolar carriers with high mobility and high saturation velocity. It also has excellent mechanical robustness and flexibility. Due to these intrinsic properties, graphene based FETs can be applied to flexible, wearable components for RF applications such as high speed wireless communication. GFETs fabricated on rigid and flexible substrate have been demonstrated by several groups [2-4]. Nevertheless, the high metal-to-graphene contact resistance remains a bottleneck factor for RF performance. i.e, current gain cut-off frequency, ft. In this work, we report a process and full characterization of GFETs based on CVD graphene on Si/SiO 2 substrate. A low contact resistance (Rc) of 125 ohm·μm with high reliability was obtained by using pure Au. From the measurement of scattering parameters, we extracted the high frequency performances of our GFETs. Best intrinsic transit frequency have been observed for transistor with 180 nm channel length, with intrinsic ft of 100 GHz at low bias of 0.5V.