Fabrication of ballistic suspended graphene with local-gating

TL;DR

This paper presents a method for fabricating high-mobility, ballistic suspended graphene nanostructures with local gating, enabling advanced electron-optics experiments and complex device architectures.

Contribution

It introduces a fabrication process for ballistic suspended graphene with local gates, including detailed gate structures and analysis of p-n junctions with Fabry-Perot oscillations.

Findings

High mobility achieved via in-situ current annealing

Observation of Fabry-Perot oscillations in p-n junctions

Extension of fabrication to multi-terminal and shaped graphene devices

Abstract

Herein we discuss the fabrication of ballistic suspended graphene nanostructures supplemented with local gating. Using in-situ current annealing, we show that exceptional high mobilities can be obtained in these devices. A detailed description is given of the fabrication of bottom and different top-gate structures, which enable the realization of complex graphene structures. We have studied the basic building block, the p-n junction in detail, where a striking oscillating pattern was observed, which can be traced back to Fabry-Perot oscillations that are localized in the electronic cavities formed by the local gates. Finally we show some examples how the method can be extended to incorporate multi-terminal junctions or shaped graphene. The structures discussed here enable the access to electron-optics experiments in ballistic graphene.