Theoretical study of the (3x2) reconstruction of beta-SiC(001)

By means of ab initio molecular dynamics and band structure calculations, as well as using calculated STM images, we have singled out one structural model for the (3x2) reconstruction of the Si-terminated (001) surface of cubic SiC, amongst several proposed in the literature. This is an alternate dimer-row model, with an excess Si coverage of 1/3, yielding STM images in good accord with recent measurements [F.Semond et al. Phys. Rev. Lett. 77, 2013 (1996)].Comment: To be published in PRB Rapid. Com

Nanostructured Graphene on beta SiC Si 001 Atomic and Electronic Structures, Magnetic and Transport Properties

The studies of the properties of graphene synthesized on the surface of epitaxial films of cubic single-crystal silicon carbide preliminarily grown on Si(001) wafers have been reviewed. These studies were supported by the Russian Foundation for Basic Research, project no. 17-02-01139. The results of these studies demonstrate that graphene layers synthesized on β-SiC/Si(001) substrates have the atomic structure and electronic properties of a quasi-freestanding graphene sheet. Continuous graphene layers with a preferential direction of nanodomain boundaries, which is determined by the orientation of steps on the initial surface, can be synthesized on vicinal SiC(001) substrates. The possibility of controlled growth of mono-, bi-, and trilayer graphene on β-SiC/Si(001) wafers has been demonstrated. The studies have shown the opening of a transport gap and a high positive magnetoresistance in a parallel magnetic field in an ordered system of graphene nanoribbons on the vicinal SiC(001) surface. It has been shown that the functionalization of graphene with organic compounds changes the electronic properties of graphene on SiC(001), modifying it to a semiconductor with given properties, which allows applications in modern micro- and nanoelectronics

Continuous wafer scale graphene on cubic SiC 001

The atomic and electronic structure of graphene synthesized on commercially available cubic SiC 001 Si 001 wafers have been studied by low energy electron microscopy LEEM , scanning tunneling microscopy STM , low energy electron diffraction LEED , and angle resolved photoelectron spectroscopy ARPES . LEEM and STM data prove the wafer scale continuity and uniform thickness of the graphene overlayer on SiC 001 . LEEM, STM and ARPES studies reveal that the graphene overlayer on SiC 001 consists of only a few monolayers with physical properties of quasi freestanding graphene. Atomically resolved STM and micro LEED data show that the top graphene layer consists of nanometersized domains with four different lattice orientations connected through the amp; 12296;110 amp; 12297; directed boundaries. ARPES studies reveal the typical electron spectrum of graphene with the Dirac points close to the Fermi level. Thus, the use of technologically relevant SiC 001 Si 001 wafers for graphene fabrication represents a realistic way of bridging the gap between the outstanding properties of graphene and their application

In situ study of multi phase indium nanoparticle growth on into CuPcF4 organic thin film in ultra high vacuum conditions

We study the in-situ growth of a nanocomposite material consisting of a thin CuPcF4 film and multiphase/multidimensional indium nanoparticles, self-organizing on the surface and in the bulk, at various stages of thermal deposition of metal on an organic film under ultrahigh vacuum conditions. The analysis of high-resolution transmission electron microscopy (HR-TEM) images provided valuable information about the evolution of morphology, size, density, and distribution of indium nanoparticles upon indium deposition. These 2D/3D ultra-small nano-objects turned out to have not only body-centered tetragonal (bct) crystal structure, typical for bulk indium, but also unusual face-centered cubic (fcc) one. Using a synchrotron facility, the study of the electronic structure of the hybrid nanocomposite on variable stages of metal deposition was performed by XPS and NEXAFS. Core-level spectra related to the organics indicated reasonably weak chemical interaction of indium with CuPcF4 molecules, which is not the case for a number of metal/organic semiconductor systems, while valence band spectra have shown a considerable change of the material electronic properties. The energy level diagrams, derived from the experiment, can be applied for the creation of new prototypes of metal-organic memory devices

Surface functionalization of few layer graphene on SiC 001 by Neutral Red dye

Few layer graphene on SiC 001 functionalized with phenazine dye Neutral Red by means of diazonium chemistry has been studied using X ray photoelectron spectroscopy, near edge X ray absorption fine structure, photoemission electron microscopy, scanning tunneling microscopy, and density functional theory calculations. The experimental data reveal the formation of a composite phenazine dye graphene structure with a large energy gap. The molecules in this structure can be oriented both parallel and perpendicular to the graphene surface. According to scanning tunneling spectroscopy and theoretical calculations, the density of electron states in different surface areas depends on the local short range order and the molecules environment. On the other hand, the photoemission spectroscopy study shows that the bottom layers of the few layer graphene remain intact, which inherently makes the synthesized layered composite a low dimensional metal semiconductor heterostructure. In addition, photoemission electron microscopy imaging shows a high homogeneity of the dye modified graphene on a micrometer scal