Negative Differential Resistance in Top-Gated Chemical Vapor Deposition Grown Graphene Transistors

Abstract Negative differential resistance (NDR) is a phenomenon in which an increase in voltage across the device's terminals results in a decrease in electric current through it. This is in contrast to a resistor in which an increase of applied voltage causes an increase in current due to Ohm's law. This unique phenomena can be exploited in numerous interesting applications, including high frequency oscillators, amplifiers, logic, memories and analog-to-digital converters. The NDR behavior can be realized with graphene transistors at high fields, thanks to its field-dependent carrier density and carrier-dependent saturation velocity, and has been demonstrated experimentally by few groups. [1]- [4] [4] showing negative values between = 1.5 V and = 1.98 V. We have proposed a novel explanation for the mechanism behind this unusual feature of graphene, relating NDR with the interplay between the field dependent carrier modulation and the drift velocity in graphene transistors. [4] In addition, we have also shown that the NDR phenomenon in graphene can be realized in transistors with relatively thicker oxide, however, the NDR in this case is achieved at relatively higher gate voltages and has a lower maximum negative differential conductance value. [4] Our demonstration of NDR using graphene grown by production-worthy CVD process opens up a new route for graphene's application in oscillators, amplifiers, switches, memories etc. References vol. 6, no. 3, pp. 2610-2616, 2012. [2] G. Liu, S. Ahsan, A. G. Khitun, R. K. Lake, and A. A. Balandin, J. Appl. Phys., vol. 114, no. 15, p. 154310, 2013. [3] S.-J. Han, D. Reddy, G. D. Carpenter, A. D. Franklin, and K. A. Jenkins, ACS Nano, vol. 6, no. 6, pp. 5220-5226, 2012.