Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
}
TY - JOUR
T1 - Nanomechanical mapping of graphene layers and interfaces in suspended graphene nanostructures grown via carbon diffusion
AU - Robinson, Benjamin
AU - Rabot, Caroline
AU - Mazzocco, Riccardo
AU - Delamoreanu, A
AU - Zenasni, Aziz
AU - Kolosov, Oleg
PY - 2014/1/1
Y1 - 2014/1/1
N2 - Graphene’s remarkable mechanical, electronic and thermal properties are strongly determined by both the mechanism of its growth and its interaction with the underlying substrate. Evidently, in order to explore the fundamentals of these mechanisms, efficient nanoscale methods are needed that enable observation of features hidden underneath the immediate surface. In this paper we use nanomechanical mapping via ultrasonic force microscopy that employs MHz frequency range ultrasonic vibrations and allows the observation of surface composition and subsurface interfaces with nanoscale resolution, to elucidate the morphology of few layer graphene (FLG) films produced via a recently reported method of carbon diffusion growth (CDG) on platinum-metal based substrate. CDG is known to result in FLG suspended over large areas, which could be of high importance for graphene transfer and applications where a standalone graphene film is required. This study directly reveals the detailed mechanism of CDG three-dimensional growth and FLG film detachment, directly linking the level of graphene decoupling with variations of the substrate temperature during the annealing phase of growth. We also show that graphene initially preferentially decouples at the substrate grain boundaries, likely due to its negative expansion coefficient at cooling, forming characteristic “nano-domes” at the intersections of the grain boundaries. Furthermore, quantitative nanomechanical mapping of flexural stiffness of suspended FLG “nano-domes” using kHz frequency range force modulation microscopy, uncovers the progression of “nano-domes” stiffness from single to bi-modal distribution as CDG growth progresses, suggesting growth instability at advanced CDG stages.
AB - Graphene’s remarkable mechanical, electronic and thermal properties are strongly determined by both the mechanism of its growth and its interaction with the underlying substrate. Evidently, in order to explore the fundamentals of these mechanisms, efficient nanoscale methods are needed that enable observation of features hidden underneath the immediate surface. In this paper we use nanomechanical mapping via ultrasonic force microscopy that employs MHz frequency range ultrasonic vibrations and allows the observation of surface composition and subsurface interfaces with nanoscale resolution, to elucidate the morphology of few layer graphene (FLG) films produced via a recently reported method of carbon diffusion growth (CDG) on platinum-metal based substrate. CDG is known to result in FLG suspended over large areas, which could be of high importance for graphene transfer and applications where a standalone graphene film is required. This study directly reveals the detailed mechanism of CDG three-dimensional growth and FLG film detachment, directly linking the level of graphene decoupling with variations of the substrate temperature during the annealing phase of growth. We also show that graphene initially preferentially decouples at the substrate grain boundaries, likely due to its negative expansion coefficient at cooling, forming characteristic “nano-domes” at the intersections of the grain boundaries. Furthermore, quantitative nanomechanical mapping of flexural stiffness of suspended FLG “nano-domes” using kHz frequency range force modulation microscopy, uncovers the progression of “nano-domes” stiffness from single to bi-modal distribution as CDG growth progresses, suggesting growth instability at advanced CDG stages.
KW - Graphene
KW - Carbon diffusion growth
KW - Ultrasonic Force Microscopy
KW - Graphene Nano-domes
KW - Nanomechanics
U2 - 10.1016/j.tsf.2013.10.093
DO - 10.1016/j.tsf.2013.10.093
M3 - Journal article
VL - 550
SP - 472
EP - 479
JO - Thin Solid Films
JF - Thin Solid Films
SN - 0040-6090
ER -