Π Band Folding and Interlayer Band Filling of Graphene upon Interface Potassium Intercalation. Issue 25 (7th August 2022)

• Record Type: Journal Article
• Authors: Huempfner, Tobias; Otto, Felix; Fritz, Torsten; Forker, Roman
• Is Part Of: Advanced materials interfaces. Volume 9:Issue 25(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-08-07
• Subjects: angle resolved ultraviolet photoelectron spectroscopy -- doping -- Fourier transform scanning tunneling microscopy -- parabolic interlayer bands -- photoemission orbital tomography; Materials science -- Periodicals; 620.11
• DOI: 10.1002/admi.202200585
• Languages: English
• ISSNs: 2196-7350

Abstract

Abstract: The structural and electronic properties of epitaxial monolayer graphene on SiC(0001) are examined upon potassium intercalation. Notably, the first real‐space observation via scanning tunneling microscopy of the (2 × 2) superstructure in graphene‐based thin films formed by the potassium atoms below the uppermost graphene layer is presented. Therein, additional signatures stemming from quasiparticle interference effects are found allowing investigations of the electronic bands of K‐intercalated epitaxial monolayer graphene on a local scale. Those data are compared to area‐averaged results obtained from photoelectron spectroscopy. In particular, backfolding of the graphene π bands are found as a consequence of the (2 × 2) superstructure of the K atoms with respect to the graphene lattice. This is accompanied by a strong n ‐type doping effect that causes a rigid shift of the Dirac bands to higher binding energies and filling of two parabolic interlayer bands at the Γ point of the surface Brillouin zone of the graphene lattice as well. This electronic configuration is promoted by additional penetration of potassium atoms into the interspace between the SiC substrate and the buffer layer that is located between the substrate and the quasi‐freestanding graphene sheet. Consequently, the epitaxial monolayer graphene sample transforms to n ‐doped epitaxial bilayer graphene upon K intercalation. Abstract : Potassium is deposited onto epitaxial monolayer graphene on SiC(0001). The K atoms go below the graphene layer and, if the K concentration is further increased, also below the buffer layer underneath. Quasiparticle interference effects and backfolding of the graphene π bands caused by the epitaxial (2 × 2) structure of potassium with respect to the graphene lattice are observed.