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

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.

7 figures, accepted by TED

References in corpus (11)

• Large-Area Synthesis of High-Quality and Uniform Graphene Films on Copper Foils
• Doping graphene with metal contacts
• Photocurrent imaging and efficient photon detection in a graphene transistor
• Evidence of the role of contacts on the observed electron-hole asymmetry in graphene
• Effects of metallic contacts on electron transport through graphene
• Conductance asymmetry of graphene pn junction
• Modeling edge effects in Graphene Nanoribbon Field-effect Transistors with real and mode space methods
• Modeling extended contacts to nanotube and graphene devices
• Charge-density depinning at metal contacts of graphene field-effect transistors
• Scalability of Atomic-Thin-Body (ATB) Transistors Based on Graphene Nanoribbons
• Assessment of High-Frequency Performance Limits of Graphene Field-Effect Transistors

Cited by in corpus (4)

• Contact-induced negative differential resistance in short-channel graphene FETs
• Exploiting negative differential resistance in monolayer graphene FETs for high voltage gains
• Recursive Green's functions optimized for atomistic modelling of large superlattice-based devices
• Semianalytical quantum model for graphene field-effect transistors