High Crystallinity and Decoupling of Graphene on a Metal: Reduced Coulomb Screening and Tunable pn-Junctions

TL;DR

This paper demonstrates high-quality epitaxial graphene on Ir(111), showing tunable pn-junctions and reduced Coulomb screening due to many-body interactions, which are crucial for advanced graphene-based electronic devices.

Contribution

It reveals how oxygen intercalation produces high-quality, quasi free-standing graphene with tunable electronic properties and reduced Coulomb screening on a metal substrate.

Findings

High structural quality of epitaxial graphene on Ir(111)

Tunable pn-junctions via adsorption and intercalation of rubidium

Reduced Coulomb screening in n-doped regions due to electron-plasmon coupling

Abstract

High quality epitaxial graphene films can be applied as templates for tailoring graphene-substrate interfaces that allow for precise control of the charge carrier behavior in graphene through doping and many-body effects. By combining scanning tunneling microscopy, angle-resolved photoemission spectroscopy and density functional theory we demonstrate that oxygen intercalated epitaxial graphene on Ir(111) has high structural quality, is quasi free-standing, and shows signatures of many-body interactions. Using this system as a template, we show that tunable pn-junctions can be patterned by adsorption and intercalation of rubidium, and that the n-doped graphene regions exhibit a reduced Coulomb screening via enhanced electron-plasmon coupling. These findings are central for understanding and tailoring the properties of graphene-metal contacts e.g. for realizing quantum tunneling devices.