Influence of Metal/Graphene Coupling on the Operation and Scalability of Graphene Field-Effect-Transistors
Pei Zhao, Qin Zhang, Debdeep Jena, Siyuranga O. Koswatta
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.
, Zhang, Q.
, Jena, D.
and Koswatta, S.
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 March 1, 2024)