Tunneling Spectroscopy of Graphene using Planar Pb Probes

TL;DR

This paper demonstrates that evaporated lead (Pb) can form high-quality tunnel probes on graphene, enabling detailed spectroscopy of electronic properties at low temperatures and high magnetic fields, revealing energy-dependent features.

Contribution

The study introduces a method to create effective tunnel probes on graphene using evaporated lead, which forms a self-limited barrier after oxidation, enabling advanced spectroscopic analysis.

Findings

Pb probes enable high-resolution tunneling spectroscopy of graphene.

Energy-dependent features such as scattering resonances are observed.

Pb probes outperform other metals like Al and Ti/Au in forming tunnel barriers.

Abstract

We show that evaporating lead (Pb) directly on graphene can create high-yield, high-quality tunnel probes, and we demonstrate high magnetic field/low temperature spectroscopy using these probes. Comparisons of Pb, Al and Ti/Au probes shows that after oxidation a well-formed self-limited tunnel barrier is created only between the Pb and the graphene. Tunneling spectroscopy using the Pb probes manifests energy-dependent features such as scattering resonances and localization behavior, and can thus be used to probe the microscopic electronics of graphene.