RF performance of top-gated, zero-bandgap graphene field-effect transistors

We present the first experimental high-frequency measurements of graphene field-effect transistors (GFETs), demonstrating an f
_T
of 14.7 GHz for a 500-nm-length device. We also present detailed measurement and analysis of velocity saturation in GFETs, demonstrating the potential for velocities approaching 10
⁸
cm/sec and the effect of an ambipolar channel on current-voltage characteristics.