Fig. 3: Stacking transfer of wafer-scale double-layer and triple-layer graphene films.
From: Stacking transfer of wafer-scale graphene-based van der Waals superlattices
a Photo of triple-layer graphene films obtained by sequential stacking 4-inch graphene to a 6-inch SiO2/Si wafer, indicating the film is homogenous on the macroscopic scale and there are no obvious folds. b Dependence between fold density and the wetting angle, the top inset is the typical optical image of graphene folds and the bottom inset is the photograph for appropriate wetting angle of ~53° to avoid the formation of folds. c Typical AFM height images of double-layer graphene and the inset height profile is taken along the dashed line, the thickness is homogenous with ~1.5 nm. d Statistical distribution of the value of G peak (ωG) across 100 × 100 μm2 of double-layer graphene, the inset is the corresponding Raman mapping. e Raman mapping of the I2D/IG across the monolayer, double-layer and triple-layer transition regions with area of 200 × 200 μm2. The distribution is homogenous in the same stacked regions of double-layer and triple-layer graphene, and is distinguished significantly in different stacked layers. f Statistical distribution of twist angles about the multiple double-layer graphene that obtained randomly and the dashed line is the fit curve, the twist angles follow the normal distribution.
