Revealing the atomic structure of the buffer layer between SiC(0 0 0 1) and epitaxial graphene

Abstract

On the SiC(0001) surface (the silicon face of SiC), epitaxial graphene is obtained by sublimation of Si from the substrate. The graphene film is separated from the bulk by a carbon-rich interface layer (hereafter called the buffer layer) which in part covalently binds to the substrate. Its structural and electronic properties are currently under debate. In the present work we report scanning tunneling microscopy (STM) studies of the buffer layer and of quasi-free-standing monolayer graphene (QFMLG) that is obtained by decoupling the buffer layer from the SiC(0001) substrate by means of hydrogen intercalation. Atomic resolution STM images of the buffer layer reveal that, within the periodic structural corrugation of this interfacial layer, the arrangement of atoms is topologically identical to that of graphene. After hydrogen intercalation, we show that the resulting QFMLG is relieved from the periodic corrugation and presents no detectable defect sites.

Local transport measurements on epitaxial graphene

“…1). Extrapolation of the band edges reveal an effective gap around 1 eV which is close to the value reported for graphene buffer layers on SiC(0001) 17,18 . STS-measurements taken at different sites within this imperfect area reveal similar spectra, i.e.…”

Application of Graphene in Surface-Enhanced Raman Spectroscopy

“…Due to abundant hydrophilic group, graphene oxide can be used as biomolecular carriers for drug and gene delivery in biomedical field [12]. Now, the preparation of graphene commonly used physical and chemical methods: micro-mechanical stripping [9], liquid exfoliation [13,14], axial cutting carbon nanotube [15], chemical vapor deposition (CVD) [16,17], crystal epitaxial growth [18] and oxidation-reduction method [19].…”

Determination of the thickness distribution of a graphene layer grown on a 2″ SiC wafer by means of Auger electron spectroscopy depth profiling

“…1. Beside the graphene the sample might consist of some C contamination on its surface and a buffer layer between the pristine SiC and graphene, which is rich in carbon [12] and has a similar structure as the graphene [13]. Thus, the Auger electron emitted by the SiC substrate is attenuated by these three layers, and the signal reaching the detector is proportional to…”

“…The intensities of the Auger electrons as a function of depth is calculated based on equations 1 and 2, where the thickness d c is taken to be 0; the contamination C will not be distinguished from the graphene. The density of the buffer layer is equal to that of graphene [13]. The EAL-s were calculated by the software of ref.…”