Dresden 2011 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 70: Gerhard Ertl Young Investigator Award

O 70.3: Vortrag

Donnerstag, 17. März 2011, 12:15–12:45, WIL C307

Substrate-Induced Mechanical Transformations in Graphene Films: A Basic Surface Science Approach Towards Controlled Nanoscale Engineering — •Nicola Ferralis — University of California, Berkeley, CA 94720, USA

Compared to research into graphene's remarkable electronic properties, much less is known about how its mechanical and elastic properties are affected by the presence of a supporting substrate. Yet, the response of graphene films to mechanical stimuli is an important fundamental surface science and nanotechnology topic, with potentially far reaching applications in high performance linear and nonlinear electronic, photonic, electrochemical and electromechanical elements. Here, the results of direct investigations of graphene's elastic and mechanical properties at the graphene-substrate interface are presented. Substrate-induced strain in epitaxial graphene grown on SiC surfaces is found to be related to the large difference in the linear expansion coefficient of graphene and the substrate. Furthermore, the amount of strain induced by the substrate is found to be tunable, through optimized graphene growth conditions, from strain-free to up to 0.1%. A comprehensive description of the temperature dependent evolution of the graphene Raman spectra is used to determine and quantify the strength of the graphene-substrate pinning. Through a comprehensive modeling of the interaction of interatomic potentials, it is found that the degree of pinning is substrate-dependent. While graphene on SiC shows a high degree of pinning, graphene grown on metal surfaces behaves as freestanding graphene.