Premium
Epitaxial Cobalt Oxide Films with Wurtzite Structure on Au(111)
Author(s) -
Ammon Maximilian,
Baumann Sara,
Kißlinger Tilman,
Rieger Janek,
Fauster Thomas,
Redinger Josef,
Hammer Lutz,
Schneider M. Alexander
Publication year - 2021
Publication title -
physica status solidi (rrl) – rapid research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.786
H-Index - 68
eISSN - 1862-6270
pISSN - 1862-6254
DOI - 10.1002/pssr.202100383
Subject(s) - wurtzite crystal structure , materials science , density functional theory , band gap , epitaxy , van der waals force , x ray photoelectron spectroscopy , electronic structure , condensed matter physics , low energy electron diffraction , photoemission spectroscopy , electron diffraction , crystallography , nanotechnology , chemistry , diffraction , computational chemistry , optics , optoelectronics , physics , nuclear magnetic resonance , layer (electronics) , molecule , hexagonal crystal system , organic chemistry
Several‐nanometer‐thick, closed, and epitaxial cobalt(II) oxide films with wurtzite crystal structure (w‐CoO) are grown on Au(111) and their structural and electronic properties analyzed. The structural quality of the ( 000 1 ¯ ) oriented, oxygen‐terminated, and unreconstructed films allow the application of surface‐science methods to unravel the properties of this unusual polymorph of CoO and may pave the way for future thin‐film applications. An experimental structural analysis by low‐energy electron diffraction (LEED‐IV) is presented with an excellent agreement between measured and calculated intensity spectra expressed by a Pendry R‐factor of R = 0.112 and few‐picometer error bounds in the parameter values. Using scanning tunneling spectroscopy (STS) the bandgap of the semiconducting films is found to be 1.4 ± 0.2 eV. Ultraviolet photoelectron spectroscopy (UPS) confirms the presence of a gap and the position of the Fermi level ( E F ). The structural results of density functional theory calculations using (hybrid) functionals to treat electron correlations and van der Waals forces agree well with the experimentally determined structure of the antiferromagnetic w‐CoO films. In contrast to generalized gradient approximation (GGA)+U calculations, the Heyd–Scuseria–Ernzerhof hybrid functional reproduces the semiconducting nature correctly and predicts surface states in the gap which might pin E F in agreement with STS and UPS.