ABSTRACT The structure and electronic properties of the interfaces formed by Re evaporation on clean Si(111)-7 × 7 and subsequent annealing were investigated by low energy electron diffraction (LEED), Photoelectron spectroscopy (XPS/XAES,... more
ABSTRACT The structure and electronic properties of the interfaces formed by Re evaporation on clean Si(111)-7 × 7 and subsequent annealing were investigated by low energy electron diffraction (LEED), Photoelectron spectroscopy (XPS/XAES, UPS) and work function (WF) measurements. Rhenium was deposited from submonolayer up to 50 ML coverages and gradually annealed up to 1100 K. Deposition causes rapid disappearance of the 7 × 7 reconstruction and the substrate UPS features, a gradual increase in the WF from 4.5 to 5.1 eV and negligible chemical shift in the XPS/XAES peaks. The interface remained abrupt with no intermixing, as metallic Re grew in a simultaneous multilayers fashion above 0.8 ML coverage. Annealing of 50 ML of Re causes a Si enrichment of the overlayer above 600 K and the formation at around 950 K of a continuous layer of silicide which remains stable up to 1100 K, whereas annealing of Re layers close to 1 ML creates ReSi2 islands on the substrate surface.
The formation of novel nanoparticles, i.e. CuO/Ta2O5 core/shell, via anodic arc-discharge in water is reported. Typical core diameters and shell thicknesses are about 20 and 5nm, respectively. Both core and shell are crystalline. The... more
The formation of novel nanoparticles, i.e. CuO/Ta2O5 core/shell, via anodic arc-discharge in water is reported. Typical core diameters and shell thicknesses are about 20 and 5nm, respectively. Both core and shell are crystalline. The resulting core/shell-structured nanopowder exhibits dielectric behavior.
The interfaces formed on the two (0001) polar faces of single crystal n-type 6H-SiC by Re evaporation and subsequent annealing were investigated by X-ray photoelectron spectroscopy (XPS), low energy electron diffraction (LEED) and work... more
The interfaces formed on the two (0001) polar faces of single crystal n-type 6H-SiC by Re evaporation and subsequent annealing were investigated by X-ray photoelectron spectroscopy (XPS), low energy electron diffraction (LEED) and work function (WF) measurements. Rhenium was deposited from submonolayer up to 2 nm thickness and gradually annealed up to 1100 K. Deposition led to a weakening and
The present work focuses on the assessment of two surface treatment procedures employed under ultra high vacuum conditions in order to obtain atomically clean graphene layers without disrupting the morphology and the two dimensional... more
The present work focuses on the assessment of two surface treatment procedures employed under ultra high vacuum conditions in order to obtain atomically clean graphene layers without disrupting the morphology and the two dimensional character of the films. Graphene layers grown by chemical vapor deposition on polycrystalline Cu were stepwise annealed up to 750°C or treated by mild Ar+ sputtering. The effectiveness of both methods and the changes that they induce on the surface morphology and electronic structure of the films were systematically studied by X-ray photoelectron spectroscopy, and electron energy loss spectroscopy. Ultraviolet photoelectron spectroscopy was employed for the study of the electronic properties of the as received sample and in combination with the work function measurements, indicated the hybridization of the C–π network with Cu d-orbitals. Mild Ar+ sputtering sessions were found to disrupt the sp2 network and cause amorphisation of the graphitic carbon. Annealing between 300°C and 450°C under ultra high vacuum proved to be an effective and lenient way for achieving an atomically clean graphene surface. At higher temperatures the rigid structure of graphene does not follow the expansion of the copper substrate leading to the graphene/Cu interface breakdown and possibly to further rippling of the graphene layers leaving bare areas of cooper substrate.
The study of matter on the nanoscale size came to boost materials science, introducing materials with improved or even novel physicochemical properties. Over the past few years an important research direction in nanomaterials synthesis is... more
The study of matter on the nanoscale size came to boost materials science, introducing materials with improved or even novel physicochemical properties. Over the past few years an important research direction in nanomaterials synthesis is the expansion from single-component ...
Publication Date: 2010
Publication Name: The Journal of Physical Chemistry C
