Figure 2.

Methodology of Raman spectroscopy. (a) Raman spectra of graphene before and after laser irradiation with 15 mW laser power for 45 s. A clear increase in I_D is observed after the treatment, corresponding to an increased defect density in the laser-irradiated region. (b) Raman spectra of five different spots irradiated with identical laser parameters show consistently enhanced D peaks and increased I_D/I_G ratios. (c) Raman map of the D band obtained from laser-irradiated spots within the contact region. The irradiated regions can be clearly identified by their enhanced D-band intensity. (d) Line profiles of the D-band intensities along the three lines indicated in (c).