| AVS 57th International Symposium & Exhibition | |
| Spectroscopic Ellipsometry Focus Topic | Friday Sessions |
| Session EL+AS+EM+MS+TF-FrM |
| Session: | Spectroscopic Ellipsometry - Inorganic Thin Films |
| Presenter: | T. Hofmann, University of Nebraska-Lincoln |
| Authors: | T. Hofmann, University of Nebraska-Lincoln A. Boosalis, University of Nebraska-Lincoln P. Kühne, University of Nebraska-Lincoln J.L. Tedesco, U.S. Naval Research Laboratory R.L. Myers-Ward, U.S. Naval Research Laboratory P.M. Campbell, U.S. Naval Research Laboratory C.R. Eddy, Jr., U.S. Naval Research Laboratory D.K. Gaskill, U.S. Naval Research Laboratory V. Shields, Cornell University S. Shivaraman, Cornell University M.G. Spencer, Cornell University W.J. Schaff, Cornell University M. Schubert, University of Nebraska-Lincoln |
| Correspondent: | Click to Email |
We have grown highest-quality epitaxial graphene on Si- and C-faces of silicon carbide substrates under various conditions. We report on Terahertz (THz), Far-infrared (FIR) and Infrared (IR) ellipsometry and THz-IR Optical Hall-effect (generalized ellipsometry in magnetic fields) investigations of the free-charge carrier properties in epitaxial graphene samples. Furthermore, new developments on the tunable-wavelength frequency-domain THz ellipsometry instrumentation with and without external magnetic will be described [2,3].
Our ellipsometric data allows the identification of multiple, parallel sheet carrier densities within the single-to-few monolayer thick graphene layers, and which crucially depend on substrate orientation and growth condition. Analysis of the multiple two-dimensional carrier sheet densities reveals their extreme yet strongly varying mobility, effective mass, and density parameters as well as the vertical carrier sheet profile. Our findings reveal striking influences of the substrate. We discuss the physical mechanisms of the substrate that influence the free-charge carrier properties in epitaxial graphene such as surface polarity, dopant incorporation, surface roughness, and defects. We present a free-charge carrier model for epitaxial graphene, its implications due to the substrate, and discuss in light of previous implementations [4].
References:
[1] Y. Taur, IBM J. of Res. & Dev. 46, 2 (2002).
[2] T. Hofmann, et al., Rev. Sci. Instrum. 81, 023101 (2010).
[3] T. Hofmann, et al., Appl. Phys. Lett. 95, 032102 (2009).
[4] Z. Q. Li, et al., Nature Physics 4, 532 (2008).