title: Large band gap opening between graphene Dirac cones induced by Na adsorption onto an Ir superlattice.
abstract: We investigate the effects of Na adsorption on the electronic structure of bare and Ir cluster superlattice-covered epitaxial graphene on Ir(111) using angle-resolved photoemission spectroscopy and scanning tunneling microscopy. At Na saturation coverage, a massive charge migration from sodium atoms to graphene raises the graphene Fermi level by ~1.4 eV relative to its neutrality point. We find that Na is adsorbed on top of the graphene layer, and when coadsorbed onto an Ir cluster superlattice, it results in the opening of a large band gap of Δ(Na/Ir/G) = 740 meV, comparable to the one of Ge and with preserved high group velocity of the charge carriers.
authors.affiliation: Istituto di Struttura della Materia, Consiglio Nazionale delle Ricerche, Trieste, Italy. marco.papagno@ism.cnr.it
authors.forename: Marco
authors.initials: M
authors.lastname: Papagno
authors.forename: Stefano
authors.initials: S
authors.lastname: Rusponi
authors.forename: Polina Makarovna
authors.initials: PM
authors.lastname: Sheverdyaeva
authors.forename: Sergio
authors.initials: S
authors.lastname: Vlaic
authors.forename: Markus
authors.initials: M
authors.lastname: Etzkorn
authors.forename: Daniela
authors.initials: D
authors.lastname: Pacilé
authors.forename: Paolo
authors.initials: P
authors.lastname: Moras
authors.forename: Carlo
authors.initials: C
authors.lastname: Carbone
authors.forename: Harald
authors.initials: H
authors.lastname: Brune
mesh_terms: D000327:Adsorption; D006108:Graphite / Q000737:chemistry*; D007495:Iridium / Q000737:chemistry*; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D012666:Semiconductors; D012964:Sodium / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D046911:Macromolecular Substances; D007495:Iridium; D006108:Graphite; D012964:Sodium