AVS 58th Annual International Symposium and Exhibition
    Graphene and Related Materials Focus Topic Tuesday Sessions
       Session GR+EM-TuM

Paper GR+EM-TuM6
Optical Properties of Graphene on MgO and SiC Polytypes Determined by Spectroscopic Ellipsometry

Tuesday, November 1, 2011, 9:40 am, Room 208

Session: Graphene: Optical Properties, Optoelectonics and Photonics
Presenter: A. Boosalis, University of Nebraska - Lincoln
Authors: A. Boosalis, University of Nebraska - Lincoln
T. Hofmann, University of Nebraska - Lincoln
S. Schoche, University of Nebraska - Lincoln
P.A. Dowben, University of Nebraska - Lincoln
S. Gaddam, University of North Texas
C. Vamala, University of North Texas
J. Kelber, University of North Texas
V. Darakchieva, Linköping University, Sweden
D.K. Gaskill, U.S. Naval Research Laboratory
M. Schubert, University of Nebraska - Lincoln
Correspondent: Click to Email

Wafer-scale production of epitaxial graphene has been demonstrated recently. It has been observed, however, that the highest quality graphene is achieved from exfoliation, while epitaxial graphene exhibits less desirable electronic and optical characteristics. Identifying substrate effects on epitaxial graphene is of paramount contemporary interest for future device production.

We have determined the complex dielectric function of graphene deposited on a number of different substrates using multiple growth techniques. The investigations were performed in the spectral range from 1.5 to 9.5 eV using spectroscopic ellipsometry. The samples studied here include graphene grown on (111) MgO using chemical vapor deposition (CVD) and graphene grown on SiC by sublimation of silicon from the substrate at high temperature. Several different SiC polytypes, including 4H, 3C, and 6H SiC were studied. Distinct differences in the complex dielectric function of graphene are observed as the underlying substrate differs in material composition and polytype. In particular in the spectral region of the exciton absorption peak (4 eV) the complex dielectric function is sensitive to both substrate and growth parameters. We compare our results with those of recent publications of graphene grown by CVD on SiO2.