Graphene Negative Differential Resistance Circuit With Voltage-Tunable High Performance at Room Temperature
We propose, fabricate, and experimentally demonstrate a circuit based on graphene field-effect transistors (GFETs) showing enhanced negative differential resistance (NDR) characteristics at room temperature. The proposed graphene NDR (GNDR) circuit consists of three GFETs, which includes a two GFET inverter connected in a feedback loop with the main GFET in which the NDR is realized. Herein, a GNDR circuit is demonstrated using large-area chemical vapor deposition grown graphene and no doping step, which makes it compatible with silicon-based circuits. The circuit shows negative differential conductance (2.1 mS/mu m) that is almost an order of magnitude better than NDR based on 1-GFET. This conductance level is uniquely tunable (x2.3) with the supply voltage as well as with the back bias voltage. It also exhibits an improved peak-to-valley current ratio (2.2) and a wide voltage range (0.6 V) over which NDR is valid. In comparison with other NDR technologies, the GNDR has a very high peak-current-density of the order of 1 mA/mu m, which offers unique opportunities for designing circuits for applications requiring high current drive.