(Color online) Schematic drawings of the main steps for PDMS transfer-printing of graphene. (a) Lightly press the PDMS stamp on to the newly cleaved bulk graphite. Remove the stamp after a few minutes. (b) Press a clean PDMS stamp to the graphite- and graphene-covered stamp repeatedly. This process cleaves the graphite on the stamp, increasing the possibility of transferring a single layer. (c) Place the PDMS stamp on the SiO2/Si wafer ensuring that the surface of the stamp is in contact with the wafer and leave in contact for a few minutes. (d) An image of graphite on PDMS as seen through an optical microscope. (e) Graphite on the SiO2/Si substrate seen through the PDMS by an optical microscope. (f) Optical imaging of the transfer process from PDMS to the SiO2 surface.
(Color online) (a) AFM (left) and SEM (right) images of the same multilayer graphene flake on top of SiO2 substrate. Notice the blisters and the corresponding particles underneath. (b) AFM image of a rippled graphene structure before (left) and after (right) thermal annealing treatment.
(Color online) (a) Optical image taken by 100 × objective lens of single and multilayer graphene. The laser spot is situated on top of the monolayer of graphene. (b) AFM image of the same region. (c) Spatially resolved Raman measurements performed in the area enclosed by the red box (“flat graphene”) and in the blue one (“blister”) as shown in the inset.
(Color online) (a) Atomic-force microscopy topographic image of graphene. The bright spots reveal the blistering of the graphene layer. (b) Phase imaging of the same region, showing the high contrast between the blistered regions and the flat one due to a different elastic response. Notice in some cases the presence of rigid structure (debris) in correspondence of the central part of the suspended membranes.
(Color online) SEM images of the same SLG region analyzed in Figs. 3 and 4. (a) Large view of the sample: the dashed line is the one where EBIE was performed. (b) SEM picture of the SLG after the spatially resolved EBIE: the obtained cut has a width of 37 nm and some blisters disappeared, relaxing on the substrate. (c) The same region after EBIE pricking of the central blister (evidenced by the red arrow). Inset: Raman spectrum on the same SLG after the EBIE process. Notice the appearance of the D peak.
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