Dresden 2014 – scientific programme
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O: Fachverband Oberflächenphysik
O 65: Poster: Graphene (HL jointly with MA, O)
O 65.5: Poster
Wednesday, April 2, 2014, 17:00–20:00, P1
Enhancing the Raman signal of graphene on SiC(0001) by using a solid immersion lens in top-down geometry — •Felix Fromm1, Martin Hundhausen2, Michl Kaiser3, Julia Krone1, and Thomas Seyller1 — 1TU Chemnitz, Institut für Physik — 2FAU Erlangen-Nürnberg, Lehrstuhl für Laserphysik — 3FAU Erlangen-Nürnberg, Lehrstuhl für Werkstoffwissenschaften
We present a study of epitaxial graphene by recording Raman spectra from the backside through the silicon carbide (SiC) substrate. In that top-down geometry we profit from the fact, that the graphene layer emits approximately 96 % of the Raman intensity into the SiC [1]. However, we only observe an intensity enhancement of approximately a factor of 4 compared to the conventional top-up geometry. This is because the solid angle of detection is decreased by refraction at the SiC/air interface and is limited by the total internal reflection. To further improve the detection efficiency, we use a high refractive index solid immersion lens (SIL) made of cubic zirconia combined with a suitable immersion liquid. By that, the angle of total internal reflection, as well as the solid angle of detection are increased. We eventually observe an increase of the detected Raman intensity towards the top-up geometry to a factor of 25. As an additional advantage, the background signal of the two-phonon Raman modes of the SiC is suppressed to a large extent.
[1] F. Fromm et al., New J. Phys. 15, 113006 (2013)