A ballistic pn junction in suspended graphene with split bottom gates

TL;DR

This paper reports the fabrication of suspended graphene devices with local bottom gates, enabling the creation of electrostatically controlled pn junctions that exhibit ballistic transport and Fabry-Perot oscillations, advancing graphene nanostructure development.

Contribution

It introduces a novel fabrication process for suspended graphene with local gates and demonstrates ballistic pn junctions with quantum interference effects.

Findings

Observation of Fabry-Perot oscillations in suspended graphene pn junctions

Ballistic transport regime achieved in the devices

High control over local electronic properties of graphene layers

Abstract

We have developed a process to fabricate suspended graphene devices with local bottom gates, and tested it by realizing electrostatically controlled pn junctions on a suspended graphene mono-layer nearly 2 micrometers long. Measurements as a function of gate voltage, magnetic field, bias, and temperature exhibit characteristic Fabry-Perot oscillations in the cavities formed by the pn junction and each of the contacts, with transport occurring in the ballistic regime. Our results demonstrate the possibility to achieve a high degree of control on the local electronic properties of ultra-clean suspended graphene layers, a key aspect for the realization of new graphene nanostructures.