Graphene wrinkling induced by monodisperse nanoparticles: facile control and quantification

Abstract

Controlled wrinkling of single-layer graphene (1-LG) at nanometer scale was achieved by introducing monodisperse nanoparticles (NPs), with size comparable to the strain coherence length, underneath the 1-LG. Typical fingerprint of the delaminated fraction is identified as substantial contribution to the principal Raman modes of the 1-LG (G and G’). Correlation analysis of the Raman shift of the G and G’ modes clearly resolved the 1-LG in contact and delaminated from the substrate, respectively. Intensity of Raman features of the delaminated 1-LG increases linearly with the amount of the wrinkles, as determined by advanced processing of atomic force microscopy data. Our study thus offers universal approach for both fine tuning and facile quantification of the graphene topography up to ~60% of wrinkling.

Graphene-enhanced Raman scattering on single layer and bilayers of pristine and hydrogenated graphene

“…Doping of the 12 C graphene layer is higher for the R6G/H-SLG sample than with the R6G/H-BLG sample. This behaviour is consistent with published data as well [48][49][50] . However, in the case of pristine graphene, no significant change of doping is observed between R6G/P-SLG and R6G/P-BLG.…”

Coexistence of Van Hove singularities and pseudomagnetic fields in modulated graphene bilayer

“…The values of AW derived from 13 C-1-LG (~ 120 NPs/µm 2 ) correspond very well with the 1-LG transferred onto a SiO2(300 nm)/Si substrate decorated with NPs of similar size and density [20]. We note that one can find wrinkles on the samples even without adding NPs on substrate, however the number and character of wrinkles induced by NPs is significantly different [20,22,27]. Based on our previous results [20,27], the typical level of delamination in the CVD-grown 1-LG transferred onto the SiO2/Si substrate is below 5%, and the main delamination is located in the few micrometer-long wrinkles (half carbon nanotube-like), which likely developed from the transfer process.…”

“…The underlayer thus includes the adhered and delaminated parts of the underlying 1-LG and the NPs as local sources of corrugation. The presence of the corrugated 1-LG with some additional local modulation by nanometer-sized objects (NPs) then leads to the formation of a 1-LG surface with different charge and strain management issues than those that were observed in previous studies [20,46]. This statement is corroborated by the fact that the reference areas show a significant amount of topography.…”

“…The initial concentration of the NPs in the dispersion (about 0.01 mol Fe/ml) was adjusted according to a previous study [16,20] in order to obtain an optimal concentration of the NPs on the substrate of around 100-150 NPs/µm 2 , thereby enabling a controlled contact regime for the top layer ( 13 C-1-LG) after the second transfer. The prepared MGBL samples were carefully checked by analysis of the AFM images as described previously [20,27]. The optimized configuration of the NPs on the substrate reveals the mean distance of around 50 nm between the NPs, which is supposed to ensure the formation of isolated topographic features around the NPs and have a negligible effect on their mutual dipole-dipole interactions [28].…”

“…This coincides with our value of AW obtained for the same sample by the AFM analysis (AW = 19%). We have to point out that relating the I(G2)/I(G1) values to the AFM data for other parts of the MGBL sample is not a perfectly rigorous process, since the general correlation curve (I(G2)/I(G1) = f(AW)) [20] is derived from a system with a different architecture and therefore a different local charge distribution. Another important point that should be addressed is the experimentally observed broadening of the Raman bands; the results obtained by the statistical analysis of the Raman maps are summarized in Table S1.…”