Quantum behavior of graphene transistors near the scaling limit

TL;DR

This paper investigates quantum interference effects in scaled graphene transistors, demonstrating phase coherent transport and Fabry-Perot oscillations in sub-100 nm devices, and explores the transition from diffusive to ballistic regimes.

Contribution

It provides new insights into quantum behavior in graphene transistors at the nanoscale, including effects of aggressive channel length scaling on device regimes.

Findings

Observation of Fabry-Perot oscillations in sub-100 nm graphene devices

Transition from diffusive to ballistic transport with channel scaling

Analysis of contact effects on device performance

Abstract

The superior intrinsic properties of graphene have been a key research focus for the past few years. However, external components, such as metallic contacts, serve not only as essential probing elements, but also give rise to an effective electron cavity, which can form the basis for new quantum devices. In previous studies, quantum interference effects were demonstrated in graphene heterojunctions formed by a top gate. Here phase coherent transport behavior is demonstrated in a simple two terminal graphene structure with clearly-resolved Fabry-Perot oscillations in sub-100 nm devices. By aggressively scaling the channel length down to 50 nm, we study the evolution of the graphene transistor from the channel-dominated diffusive regime to the contact-dominated ballistic regime. Key issues such as the current asymmetry, the question of Fermi level pinning by the contacts, the graphene screening determining the heterojunction barrier width, the scaling of minimum conductivity and of the on/off current ratio, are investigated.