Graphene Field-Effect Transistors with Boron-Nitride Dielectric Interfaces for RF Applications

There has been growing interest in graphene as a replacement for III-V materials in MMIC applications because of its high mobility, its potential for high saturation velocity, and its nearly perfect two-dimensional electrostatics.  We summarize ongoing efforts to design and characterize graphene field-effect transistors (GFETs).   We demonstrate the importance of high quality dielectric interfaces to graphene, and the advantages of boron nitride as a dielectric interface material. We present detailed measurement and analysis of velocity saturation in GFETs, demonstrating the potential for velocities approaching 10⁸ cm/sec and the effect of an ambipolar channel on current-voltage characteristics. We find that the saturation velocity is sheet-carrier dependent and limited by phonon emission.   We describe on-going challenges in achieving low contact resistances and making scalable device structures.