Performance comparison of Graphene and Silicon nanowire transistors

Abstract

Graphene nanoribbons and carbon nanotubes represent a novel class of low-dimensional materials. All these graphene based nanostructures are expected to exhibit the extraordinary electronic properties and therefore these are the promising candidates for a wide range of nanoscience and nanotechnology applications. So, in this work, the performance potential of ballistic graphene and silicon nanowire field effect transistors are examined for future high performance applications. CNT is graphite sheet with a hexagonal lattice that has been wrapped up into a seamless cylinder. GNR consists of carbon atoms arranged in a 2-dimensional honeycomb crystal lattice. And rode like silicon crystals with a diameter of less than 100 nm is referred to as SiNW. These materials are being used as the channel materials of the transistors. In this work drain current ID, transconductance gm, number of mobile charge, quantum capacitance CQ, gate capacitance CG, gate delay τ and cut off frequency fT of GNR, CNT and SiNW transistors have been calculated using ballistic top of the barrier model and then we plot those variables with respect to gate bias. To realize the performance of these three types of transistors, it is necessary to compare those characteristics with each other. On-current in carbon based channel is higher as well as ION/IOFF is higher than SiNW channel due to lower effective mass. Higher on-current indicates sharper slope in current curve which ensures higher transconductance. So, CNT transistor has the highest transconductance. The density of states(DOS) of CNT and GNR transistors are lower than SiNW transistor. And the reason behind small gate capacitance is low density of states. On-current, transconductance and gate capacitance control the switching speed of a transistor. So from the simulations it seems that graphene transistors can be the candidates for future digital switches. But it is also important that SiNWs in particular are potentially very attractive, given the central role of silicon in the semiconductor industry and the existing set of known fabrication technologies.