Mapping nanomechanical phenomena of graphene nanostructures using force modulation and ultrasonic force microscopy

O.V. Kolosov, N.D. Kay, B.J. Robinson, M. Rosamond, D. Zeze, F. Dinelli
Lancaster University, UK

Keywords: nanomechanics, graphene, adhesion, interface, buckling, delamination, elasticity, ultrasonic force microscopy, UFM

Summary:

Whereas graphene electronic properties are extensively studied, mechanical properties of graphene nanostructures are much less experimentally explored even for simple graphene structures. We use a combination of force sensitive scanning probe microscopies that combines low frequency and ultrasonic vibrations from kHz to 10 MHz frequency that enables direct nanomechanical mapping of graphene suspended and supported nanostructures with dynamic range of stiffness from 0.02 to 2000 N/m and lateral resolution of few nanometres. We imaged residual stresses in supported graphene layers that revealed themselves as broken mechanical contact at the interface between graphene layer and the substrate, as well as to explore nanomechanical behaviour of suspended graphene films. We directly observed the transition of graphene layer deformation from plate to stretched membrane behaviour, as well created nanoscale maps of shell instability (buckling) for few layer graphene sheets, providing insight to the stresses in the free standing graphene films.