Operation of multi-finger graphene quantum capacitance varactors using planarized local bottom gate electrodes

The operation of multi-finger graphene quantum capacitance varactors fabricated using a planarized local bottom gate electrode, HfO2 gate dielectric, and large-area graphene is described. As a function of the gate bias, the devices show a room-temperature capacitance tuning range of 1.22-1 over a voltage range of +/-2V. An excellent theoretical fit of the temperature-dependent capacitance-voltage characteristics is obtained when random potential fluctuations with standard deviation of 65mV are included. The results represent a first step in realizing graphene quantum capacitance varactors for wireless sensing applications. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3698394]