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Ultra Long-Range Interactions between Large Area Graphene and Silicon
Na, Seung Ryul,Suk, Ji Won,Ruoff, Rodney S.,Huang, Rui,Liechti, Kenneth M. American Chemical Society 2014 ACS NANO Vol.8 No.11
<P>The wet-transfer of graphene grown by chemical vapor deposition (CVD) has been the standard procedure for transferring graphene to any substrate. However, the nature of the interactions between large area graphene and target substrates is unknown. Here, we report on measurements of the traction–separation relations, which represent the strength and range of adhesive interactions, and the adhesion energy between wet-transferred, CVD grown graphene and the native oxide surface of silicon substrates. These were determined by coupling interferometry measurements of the separation between the graphene and silicon with fracture mechanics concepts and analyses. The measured adhesion energy was 357 ± 16 mJ/m<SUP>2</SUP>, which is commensurate with van der Waals interactions. However, the deduced traction–separation relation for graphene-silicon interactions exhibited a much longer range interaction than those normally associated with van der Waals forces, suggesting that other mechanisms are present.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2014/ancac3.2014.8.issue-11/nn503624f/production/images/medium/nn-2014-03624f_0009.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn503624f'>ACS Electronic Supporting Info</A></P>
Probing the adhesion interactions of graphene on silicon oxide by nanoindentation
Suk, Ji Won,Na, Seung Ryul,Stromberg, Ryan J.,Stauffer, Douglas,Lee, Jinkee,Ruoff, Rodney S.,Liechti, Kenneth M. Elsevier 2016 Carbon Vol.103 No.-
<P>Although a variety of fundamental mechanical properties of graphene have been investigated, the nature of interactions between graphene and other materials is not yet fully understood. Here, we report on adhesive interactions between diamond indenters and monolayer, bilayer and trilayer graphene on silicon oxide as well as bare silicon oxide and graphite over relatively small spatial domains. Displacement-controlled nanoindentation with an ultralow noise force sensor allowed the complete adhesive responses to be observed without the usual instabilities associated with nanoindenters that operate in force control. It was found that the approach and withdrawal force profiles between diamond and graphene depended on the number of layers of graphene. The unloading response contained very characteristic features, which were attributed to separation between graphene and silicon oxide in subsequent stress analyses of the experiments. The numerical stress analyses accounted for the interactions between the probe and the graphene as well as between graphene and silicon oxide via traction-separation relations which included attractive and repulsive interactions. As a result, it was possible to extract the energy, strength and range of the interactions for all cases, thereby providing a much richer measure of the interactions than relying solely on force profiles. (C) 2016 Elsevier Ltd. All rights reserved.</P>