We report on the structural and electronic properties of a single bismuth layer intercalated underneath a graphene layer grown on an Ir(111) single crystal. Scanning tunneling microscopy (STM) reveals a hexagonal surface structure and a dislocation network upon Bi intercalation, which we attribute to a 3×3R30deg Bi structure on the underlying Ir(111) surface. Ab-initio calculations show that this Bi structure is the most energetically favorable, and also illustrate that STM measurements are most sensitive to C atoms in close proximity to intercalated Bi atoms. Additionally, Bi intercalation induces a band gap (Eg=0.42eV) at the Dirac point of graphene and an overall n-doping (∼0.39eV), as seen in angular-resolved photoemission spectroscopy. We attribute the emergence of the band gap to the dislocation network which forms favorably along certain parts of the moir\'e structure induced by the graphene/Ir(111) interface.
@article{arxiv.1603.08724,
title = {Band gap engineering by Bi intercalation of graphene on Ir(111)},
author = {Jonas Warmuth and Albert Bruix and Matteo Michiardi and Torben Hänke and Marco Bianchi and Jens Wiebe and Roland Wiesendanger and Bjørk Hammer and Philip Hofmann and Alexander A. Khajetoorians},
journal= {arXiv preprint arXiv:1603.08724},
year = {2016}
}