Single-layer graphene microislands with smooth edges and no visible grain boundary were epitaxially grown on the C-face of 4H-SiC and then characterized at the nanoscale using tip-enhanced Raman spectroscopy (TERS). Although these graphene islands appear highly homogeneous in micro-Raman imaging, TERS reveals the nanoscale strain variation caused by ridge nanostructures. A G' band position shift up to 9 cm(-1) and a band broadening up to 30 cm(-1) are found in TERS spectra obtained from nanoridges, which is explained by the compressive strain relaxation mechanism. The small size and refined nature of the graphene islands help in minimizing the inhomogeneity caused by macroscale factors, and allow a comparative discussion of proposed mechanisms of nanoridge formation.
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http://dx.doi.org/10.1039/c5cp05014f | DOI Listing |
Appl Spectrosc
November 2020
School of Science and Technology, Kwansei Gakuin University, Sanda, Hyogo, Japan.
Interactions between epitaxial graphene grown on Si- and C-faces were investigated using Raman imaging and tip-enhanced Raman scattering (TERS). In the TERS spectrum, which has a spatial resolution exceeding the diffraction limit, a D band was observed not from graphene surface, but from the edges of the epitaxial graphene ribbons without a buffer layer, which interacts with SiC on the Si-face. In contrast, for a graphene micro-island on the C-face, the D band disappeared even on the edges where the C atoms were arranged in armchair configurations.
View Article and Find Full Text PDFACS Appl Mater Interfaces
May 2020
Department of Bioengineering, McGill University, Montreal, Quebec H3A 0E9, Canada.
Hierarchical 3D gold nano-/microislands (NMIs) are favorably structured for direct and probe-free capture of bacteria in optical and electrochemical sensors. Moreover, their unique plasmonic properties make them a suitable candidate for plasmonic-assisted electrochemical sensors, yet the charge transfer needs to be improved. In the present study, we propose a novel plasmonic-assisted electrochemical impedimetric detection platform based on hybrid structures of 3D gold NMIs and graphene (Gr) nanosheets for probe-free capture and label-free detection of bacteria.
View Article and Find Full Text PDFBiosens Bioelectron
March 2017
CSIRO Manufacturing, P.O. Box 218, 36 Bradfield Road, Lindfield, NSW 2070, Australia; School of Physics, The University of Sydney, Sydney, NSW 2006, Australia; Institute for Future Environments and Institute for Health and Biomedical Innovation, School of Chemistry, Physics, and Mechanical Engineering, Queensland University of Technology, Brisbane QLD 4000, Australia. Electronic address:
Here, we present a rapid, low-temperature (200°C) plasma-enabled synthesis of graphene micro-islands (GMs). Morphological analyses of GMs by scanning electron microscopy (SEM) and atomic force microscopy (AFM) feature a uniform and open-networked array of aggregated graphene sheets. Structural and surface chemical characterizations by Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) support the presence of thin graphitic edges and reactive oxygen functional groups.
View Article and Find Full Text PDFPhys Chem Chem Phys
November 2015
Department of Chemistry, School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan.
Single-layer graphene microislands with smooth edges and no visible grain boundary were epitaxially grown on the C-face of 4H-SiC and then characterized at the nanoscale using tip-enhanced Raman spectroscopy (TERS). Although these graphene islands appear highly homogeneous in micro-Raman imaging, TERS reveals the nanoscale strain variation caused by ridge nanostructures. A G' band position shift up to 9 cm(-1) and a band broadening up to 30 cm(-1) are found in TERS spectra obtained from nanoridges, which is explained by the compressive strain relaxation mechanism.
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