Current crowding mediated large contact noise in graphene field-effect transistors

TL;DR

This study investigates contact noise in graphene FETs, revealing that current crowding at the contacts significantly contributes to resistance fluctuations, especially in high mobility devices, impacting device performance.

Contribution

It introduces a phenomenological model linking contact noise to current crowding and electrostatic fluctuations, highlighting the dominance of contact noise across various device configurations.

Findings

Contact noise is dominated by current crowding effects.

Contact noise significantly affects high mobility graphene devices.

Electrostatic fluctuations at the metal-channel interface are a key microscopic origin.

Abstract

The impact of the intrinsic time-dependent fluctuations in the electrical resistance at the graphene-metal interface or the contact noise, on the performance of graphene field effect transistors, can be as adverse as the contact resistance itself, but remains largely unexplored. Here we have investigated the contact noise in graphene field effect transistors of varying device geometry and contact configuration, with carrier mobility ranging from 5,000 to 80,000$~$cm$^{2}$V$^{-1}$s$^{-1}$. Our phenomenological model for contact noise due to current crowding in purely two dimensional conductors, confirms that the contacts dominate the measured resistance noise in all graphene field effect transistors in the two-probe or invasive four probe configurations, and surprisingly, also in nearly noninvasive four probe (Hall bar) configuration in the high mobility devices. The microscopic origin of contact noise is directly linked to the fluctuating electrostatic environment of the metal-channel interface, which could be generic to two dimensional material-based electronic devices.