Room-Temperature High On/Off Ratio in Suspended Graphene Nanoribbon Field Effect Transistors

TL;DR

This study demonstrates that controlled current annealing of suspended graphene nanoribbons can produce high on/off ratios exceeding 10^4 at room temperature, with stable electrical properties and intrinsic ambipolar behavior.

Contribution

It is the first to show that wide graphene nanoribbons can achieve high on/off ratios and ambipolar characteristics through current annealing.

Findings

High on/off ratio (>10^4) achieved at room temperature.

Current annealing removes impurities and induces band-gap formation.

Devices exhibit thermal and mechanical stability over repeated cycles.

Abstract

We have fabricated suspended few layer (1-3 layers) graphene nanoribbon field effect transistors from unzipped multiwall carbon nanotubes. Electrical transport measurements show that current-annealing effectively removes the impurities on the suspended graphene nanoribbons, uncovering the intrinsic ambipolar transfer characteristic of graphene. Further increasing the annealing current creates a narrow constriction in the ribbon, leading to the formation of a large band-gap and subsequent high on/off ratio (which can exceed 104). Such fabricated devices are thermally and mechanically stable: repeated thermal cycling has little effect on their electrical properties. This work shows for the first time that ambipolar field effect characteristics and high on/off ratios at room temperature can be achieved in relatively wide graphene nanoribbon (15 nm ~50 nm) by controlled current annealing.