Structure and electronic states of a graphene double vacancy with an embedded Si dopant

Autor(en)

Reed Nieman, Adelia J. A. Aquino, T.P. Hardcastle, Jani Kotakoski, Toma Susi, Hans Lischka

Abstrakt

Silicon represents a common intrinsic impurity in graphene, bonding to either three or four carbon neighbors, respectively, in a single or double carbon vacancy. We investigate the effect of the latter defect (Si-C

₄) on the structural and electronic properties of graphene using density functional theory. Calculations based both on molecular models and with periodic boundary conditions have been performed. The two-carbon vacancy was constructed from pyrene (pyrene-2C) which was then expanded to circumpyrene-2C. The structural characterization of these cases revealed that the ground state is slightly non-planar, with the bonding carbons displaced from the plane by up to ±0.2 Å. This non-planar structure was confirmed by embedding the defect into a 10 × 8 supercell of graphene, resulting in 0.22 eV lower energy than the previously considered planar structure. Natural bond orbital analysis showed sp

³ hybridization at the silicon atom for the non-planar structure and sp

²d hybridization for the planar structure. Atomically resolved electron energy loss spectroscopy and corresponding spectrum simulations provide a mixed picture: a flat structure provides a slightly better overall spectrum match, but a small observed pre-peak is only present in the corrugated simulation. Considering the small energy barrier between the two equivalent corrugated conformations, both structures could plausibly exist as a superposition over the experimental time scale of seconds.

Organisation(en)

Physik Nanostrukturierter Materialien

Externe Organisation(en)

Texas Tech University, Tianjin University, SuperSTEM Laboratory, University of Leeds

Journal

Journal of Chemical Physics

Band

147

Anzahl der Seiten

9

ISSN

0021-9606

Publikationsdatum

11-2017

Peer-reviewed

Ja

ÖFOS 2012

104017 Physikalische Chemie, 103009 Festkörperphysik

Schlagwörter

ASJC Scopus Sachgebiete

Allgemeine Physik und Astronomie, Physical and Theoretical Chemistry

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/39686d1f-9e48-4e9b-b049-9ce389547866