29 Oct 2008 | C. Casiraghi, A. Hartschuh, H. Qian, S. Piscanec, C. Georgi, K. S. Novoselov, D. M. Basko, A. C. Ferrari
This paper presents a detailed Raman spectroscopic investigation of graphene flakes with well-defined edges oriented at different crystallographic directions. The study focuses on the position, width, and intensity of the G and D peaks, which are sensitive to the incident light polarization. The D-band is strongest when the light is polarized parallel to the edge and minimum when it is perpendicular. Raman mapping reveals that the D peak is localized near the edge, but the D to G ratio does not always show a significant dependence on edge orientation. This suggests that even though edges may appear smooth and oriented at well-defined angles, they are not necessarily microscopically ordered. The results challenge the notion that perfectly armchair or zigzag edges can be easily obtained during exfoliation, despite their macroscopic appearance. The study also discusses the conditions under which the D peak is activated and the impact of edge disorder on its intensity. Overall, Raman spectroscopy is shown to be a powerful tool for probing the electronic properties of graphene edges.This paper presents a detailed Raman spectroscopic investigation of graphene flakes with well-defined edges oriented at different crystallographic directions. The study focuses on the position, width, and intensity of the G and D peaks, which are sensitive to the incident light polarization. The D-band is strongest when the light is polarized parallel to the edge and minimum when it is perpendicular. Raman mapping reveals that the D peak is localized near the edge, but the D to G ratio does not always show a significant dependence on edge orientation. This suggests that even though edges may appear smooth and oriented at well-defined angles, they are not necessarily microscopically ordered. The results challenge the notion that perfectly armchair or zigzag edges can be easily obtained during exfoliation, despite their macroscopic appearance. The study also discusses the conditions under which the D peak is activated and the impact of edge disorder on its intensity. Overall, Raman spectroscopy is shown to be a powerful tool for probing the electronic properties of graphene edges.