Raman spectroscopy of epitaxial graphene on a SiC substrate

Abstract

The fabrication of epitaxial graphene (EG) on SiC substrate by annealing has attracted a lot of interest as it may speed up the application of graphene for future electronic devices. The interaction of EG and the SiC substrate is critical to its electronic and physical properties. In this work, Raman spectroscopy was used to study the structure of EG and its interaction with SiC substrate. All the Raman bands of EG blue shift from that of bulk graphite and graphene made by micromechanical cleavage, which was attributed to the compressive strain induced by the substrate. A model containing 13 × 13 honeycomb lattice cells of graphene on carbon nanomesh was constructed to explain the origin of strain. The lattice mismatch between graphene layer and substrate causes the compressive stress of 2.27 GPa on graphene.We also demonstrate that the electronic structures of EG grown on Si and C terminated SiC substrates are quite different. Our experimental results shed light on the interaction between graphene and SiC substrate that are critical to the future applications of EG.

Raman spectroscopy and imaging of graphene

“…In this section, we present Raman studies of epitaxial graphene (EG) grown on SiC substrates [55]. EG grown on SiC is suitable for large area fabrication and is more compatible with current Si processing techniques for future applications.…”

“…Therefore, the lattice mismatch between the graphene lattice and interfacial carbon layer may cause a compressive stress on EMG, giving rise to the shift in the Raman G band peak frequencies. Detailed studies of epitaxial graphene on a SiC substrate will be described in Section 7 [55].…”

Raman Topography and Strain Uniformity of Large-Area Epitaxial Graphene

“…Micro-Raman spectroscopy is a rapid, highresolution optical characterization technique that yields important information on the thickness, the charge carrier density, and the strain of epitaxial graphene. 10,11,12,13 However, no studies of Raman topography, the two-dimensional mapping of Raman spectrum over large-area epitaxial graphene, have been carried out to date. …”

Graphene made easy: High quality, large-area samples

“…In the case of micro-mechanical cleaving these include sample size and inadaptability to large scale applications. In the case of annealed SiC, there are questions regarding sample quality 5 and the method is relevant only to graphene. We have developed a simple, inexpensive and fast method for producing larger graphene samples, and two dimensional samples of layered materials in general.…”