| AVS 60th International Symposium and Exhibition | |
| Graphene and Other 2D Materials Focus Topic | Wednesday Sessions |
| Session GR+AS+EM+NS+SS-WeA |
| Session: | Dopants, Defects and Interfaces in 2D Materials |
| Presenter: | Q. Tu, Duke University |
| Authors: | Q. Tu, Duke University Z. Parlak, Duke University R. Ferris, Duke University S. Zauscher, Duke University |
| Correspondent: | Click to Email |
Graphene has extraordinary mechanical and electrical properties and has been demonstrated wide applications in flexible electronics and sensors. Most of the graphene-based devices functionalizes with graphene on a substrate. The conformation of graphene to the substrate and the bonding between graphene and substrate[1] will influence the electronic properties of graphene[2] and the stress transferred from the substrate to graphene, which is a big issue of device stability. Herein we show that the defects in graphene-substrate interface could be nondestructively detected by atomic force acoustic microscopy (AFAM), which is a dynamic AFM technique sensitive to the tip-sample contact stiffness. The contact stiffness mapping indicates that the graphene covered silicon was softer than uncovered area, which contradicts that graphene is the stiffest material ever known. This is due to the cavity and water molecules present in the graphene-substrate interface. With the topography data, a layered structure model is built up and the simulated contact stiffness mapping matches the experiment well. In addition, graphene was transferred to a substrate with patterened surface chemistry and the contact stiffness in hydrophobic area is higher than that in hydrophilic area, which indicates that reducing water molecules in the interface would increase the graphene-substrate contact.
[1] L. H. Liu and M. D. Yan, "Simple Method for the Covalent Immobilization of Graphene," vol. 9, pp. 3375-3378, Sep 2009.
[2] M. Lafkioti, B. Krauss, T. Lohmann, U. Zschieschang, H. Klauk, K. von Klitzing, and J. H. Smet, "Graphene on a Hydrophobic Substrate: Doping Reduction and Hysteresis Suppression under Ambient Conditions," vol. 10, pp. 1149-1153, Apr 2010.