Influence of Metal/Graphene Coupling on the Operation and Scalability of Graphene Field-Effect-Transistors

Published

August 24, 2011

Author(s)

Pei Zhao, Qin Zhang, Debdeep Jena, Siyuranga O. Koswatta

Abstract

We explore the effects of metal contacts on the operation and scalability of 2D Graphene Field-Effect-Transistors (GFETs) using detailed numerical device simulations based on the non-equilibrium Green's function formalism self-consistently solved with the Poisson equation at the ballistic limit. Our treatment of metal-graphene (M-G) contacts captures: (1) the doping effect due to the shift of the Fermi level in graphene contacts, (2) the density-of-states (DOS) broadening effect inside graphene contacts due to Metal-Induced-States (MIS). Our results confirm the asymmetric transfer characteristics in GFETs due to the doping effect by metal contacts. Furthermore, at higher M-G coupling strengths the contact DOS broadening effect increases the on-current, while the impact on the minimum current (Imin) in the off-state depends on the source to drain bias voltage and the work-function difference between graphene and the contact metal. Interestingly, with scaling of the channel length, the MIS inside the channel has a weak influence on Imin even at large M-G coupling strengths, while direct source-to-drain (S D) tunneling has a stronger influence. Therefore, channel length scalability of GFETs with sufficient gate control will be mainly limited by direct S D tunneling, and not by the MIS.

Citation

IEEE Transactions on Electron Devices

Volume

58

Issue

9

Pub Type

Journals

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Keywords

Graphene, Field-Effect-Transistors, Metal Induced States, Density-of-States Broadening, Source to Drain Tunneling

Citation

Zhao, P. , Zhang, Q. , Jena, D. and Koswatta, S. (2011), Influence of Metal/Graphene Coupling on the Operation and Scalability of Graphene Field-Effect-Transistors, IEEE Transactions on Electron Devices, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=907183 (Accessed January 13, 2025)