Host: The Japan Society of Vacuum and Surface Science
Structural instability of graphene films epitaxially-grown on SiC(0001) upon photoexcitation has been studied by Raman scattering spectroscopy. For as-grown graphene films, a broad 2D-peak originated from the double phonon-scattering were observed at 2705cm-1, demonstrating several monolayers of graphene layers grown on the substrate. Under excitation with 800nm laser pulses of 100fs, the intensity decreases at higher energy part of the 2D peak, while increases at lower energy part. The photo-induced change indicates strongly that graphene layers are exfoliated selectively from multilayer domains resulting in the expansion of single-layer domains under photoexcitation. Based on the results, we conclude that the efficiency of photo-induced exfoliation of graphene layers depends strongly on the number of layers of graphene films, and that single-layer graphene on SiC is highly resistive against the photoexcitation.
