Abstract
Few-layer graphene (FLG) samples prepared by two methods (chemical vapour deposition on copper followed by transfer onto SiO2/Si substrate and mechanical exfoli-ation) are characterised by combined optical contrast and micro-Raman mapping experiments. We examine the be-haviour of the integrated intensity ratio of the 2D and G bands (A2D/AG) and of the 2D band width (2D) as a function of the number of layers (N). For our mechanically exfoliated FLG, A2D/AG decreases and 2D increases with N as expected for commensurately stacked FLG. For CVD grown FLG (2 to 6 layers), both similar and opposite behaviours are observed and are ascribed to dif-ferent stacking orders. For small (resp. large) relative ro-tation angle between adjacent layers (), the values of the A2D/AG ratio is smaller (resp. larger) and the 2D band is broader (resp. narrower) than for single layer graphene. Moreover, the A2D/AG ratio decreases (resp. increases) and, conversely, 2D increases (resp. decreases) as a function of N for small (resp. large) . An intermediate behaviour has also been found and is interpreted as the presence of both small and large within the studied area. In terms of characterisation criteria, these results confirm that neither A2D/AG nor 2D are definitive criteria to iden-tify single layer graphene, or to count the number of layers in FLG.