Visible to vacuum ultraviolet dielectric functions of epitaxial graphene on 3C and 4H SiC polytypes determined by spectroscopic ellipsometry

A. Boosalis, T. Hofmann, V. Darakchieva, R. Yakimova, Mathias Schubert

Research output: Contribution to journalArticle

25 Citations (Scopus)

Abstract

Spectroscopic ellipsometry measurements in the visible to vacuum-ultraviolet spectra (3.5-9.5 eV) are performed to determine the dielectric function of epitaxial graphene on SiC polytypes, including 4H (C-face and Si-face) and 3C SiC (Si-face). The model dielectric function of graphene is composed of two harmonic oscillators and allows the determination of graphene quality, morphology, and strain. A characteristic van Hove singularity at 4.5 eV is present in the dielectric function of all samples, in agreement with observations on exfoliated as well as chemical vapor deposited graphene in the visible range. Model dielectric function analysis suggests that none of our graphene layers experience a significant degree of strain. Graphene grown on the Si-face of 4H SiC exhibits a dielectric function most similar to theoretical predictions for graphene. The carbon buffer layer common for graphene on Si-faces is found to increase polarizability of graphene in the investigated spectrum.

Original languageEnglish (US)
Article number011912
JournalApplied Physics Letters
Volume101
Issue number1
DOIs
StatePublished - Jul 2 2012

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ellipsometry
graphene
vacuum
ultraviolet spectra
trucks
harmonic oscillators
buffers
vapors
carbon
predictions

ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)

Cite this

Visible to vacuum ultraviolet dielectric functions of epitaxial graphene on 3C and 4H SiC polytypes determined by spectroscopic ellipsometry. / Boosalis, A.; Hofmann, T.; Darakchieva, V.; Yakimova, R.; Schubert, Mathias.

In: Applied Physics Letters, Vol. 101, No. 1, 011912, 02.07.2012.

Research output: Contribution to journalArticle

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