| AVS 60th International Symposium and Exhibition | |
| Spectroscopic Ellipsometry Focus Topic | Wednesday Sessions |
| Session EL+AS+EM+SS+TF-WeA |
| Session: | Spectroscopic Ellipsometry: Perspectives and Novel Applications |
| Presenter: | P. Kühne, Univ. of Nebraska-Lincoln |
| Authors: | P. Kühne, Univ. of Nebraska-Lincoln V. Darakchieva, Linköping Univ., Sweden J.L. Tedesco, ABB, Inc R.L. Myers-Ward, U.S. Naval Research Lab C.R. Eddy, Jr., U.S. Naval Research Lab D.K. Gaskill, U.S. Naval Research Lab C.M. Herzinger, J.A. Woollam Co., Inc. M. Schubert, Univ. of Nebraska-Lincoln T. Hofmann, Univ. of Nebraska-Lincoln |
| Correspondent: | Click to Email |
We report on polarization sensitive, magneto-optic, reflection-type Landau level (LL) spectroscopy at low temperatures by using the optical-Hall effect in the mid-infrared spectral range (from 600 to 4000 cm−1) on epitaxial graphene grown on C-face silicon carbide by thermal decomposition. In contrast to transmission measurements, our reflection-type ellipsometry setup allows simultaneous detection of Landau level transitions, and the classical Drude-type magneto-optic free charge carrier contribution throughout the full mid-infrared spectral range, including the opaque Reststrahlen band of the SiC substrate. In this region, we observe a multitude of LL transitions that can be assigned to single-, bi- and Bernal stacked (ABA) tri-layer graphene.12 For the first time, we observe symmetric and anti-symmetric signatures due to non-polarizing, i.e., isotropic, and polarizing, i.e., anisotropic Landau level transitions, respectively. Isotropic polarization behavior is found for LL transitions exhibiting a square-root dependence on the magnetic field, typical for stacks of decoupled graphene mono-layers. Anisotropic polarization behavior is observed for LL transitions with a sub-linear to linear dependence on the magnetic field, indicative for bi- and ABA stacked tri-layer graphene. We present a dielectric model describing contributions from the substrate, Drude-type free charge carrier and symmetric and non-symmetric Landau level transitions. Model parameters as the average velocity of Dirac fermions c = (1.01±0.01) 106 m/s and interlayer coupling constant γ = (3150±50) cm-1are found to been in excellent agreement with previously reported values.
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[2] M. Orlita, C. Faugeras, R. Grill, C. Berger, W. A. de Heer, G. Martinez, M. Potemski, et al., Phys. Rev. Lett. 107, 216603 (2011).