Growth and Surface Properties of Cuprous Oxide Films on Au(111)

Abstract

Reactive Cu deposition in an O2 ambience is used to prepare homogeneous copper oxide films on an Au(111) support. X-ray photoelectron spectroscopy reveals a predominant Cu2O stoichiometry of the ad-layers. Their growth morphology and atomic structure is determined with scanning tunneling microscopy (STM) and low-energy electron diffraction. The films grow in a layer-by-layer fashion and expose different terminations depending on the preparation conditions. While as-prepared films develop a variety of surface reconstructions, the structure of postannealed films is similar to the one of bulk-cut Cu2O(111). STM conductance spectroscopy is used to probe the local electronic structure and work function of the material. Apart from the ∼2.0 eV band gap of Cu2O, an unoccupied surface state is identified for annealed films. The high crystallographic quality of the cuprous oxide films renders them suitable for further investigations of the defect landscape and the optical properties of this reference material for photocatalysis and photovoltaics.

Incorrect DFT-GGA predictions of the stability of non-stoichiometric/polar dielectric surfaces: the case of Cu2O(111)

“…The oxide chemical composition has been determined to be close to Cu 2 O, employing core level and Auger spectroscopy. 18 According to STM measurements, the films homogenously wet the Au(111) surface and form large terraces delimited by the initial step edges of the support (Fig. 1a).…”

Negative differential conductance in the electron-transport through copper-rich cuprous oxide thin films

“…Differential conductance data were recorded with a lockin amplifier at 15 mV modulation bias and 1350 Hz. The oxide films were prepared by reactive Cu deposition onto a sputtered and annealed Au(111) single crystal in 5×10 −6 mbar oxygen ambience [21]. To stimulate crystallisation, the films were post-annealed in vacuum to 600 K until a sharp (2×2) spot pattern with respect to the primitive Au (1×1) was detected in electron diffraction.…”

Temperature-dependent phase evolution of copper-oxide thin-films on Au(111)

“…The oxide films were prepared by Cu deposition (99.99% purity) onto a sputtered and annealed Au(111) single crystal in 5 Â 10 À6 mbar of oxygen at room temperature. 28 Deposition rate and initial Cu thickness were set to 1 ML min À1 and 5 ML, respectively, as calibrated with the Cu2p/Au4f intensity ratio of a metallic Cu/Au(111) reference in X-ray photoelectron spectra. After deposition, the samples were gently annealed in vacuum to promote film ordering.…”

“…26,27 In recent experiments, we have used the Au(111) surface for copper-oxide growth, as it features a rather small lattice mismatch of 4.4% only. 28,29 Indeed, (111)-oriented Cu 2 O films of high structural quality could be grown over a wide range of preparation conditions. Here, we concentrate on alternative oxide polymorphs, such as Au[1% 10] and [11% 2]-oriented Cu-O stripes as well as (2 Â 2) Cu-O networks, emerging at different growth temperatures and oxygen pressures.…”