| dc.description.abstract |
Roughness and defects induced on few-layer graphene (FLG) irradiated by Ar+ ions at different energies were
investigated using X-ray photoemission spectroscopy (XPS) and atomic force microscopy techniques. The results
provide direct experimental evidence of ripple formation, sp2 to sp3 hybridized carbon transformation, electronic
damage, Ar+ implantation, unusual defects and edge reconstructions in FLG, which depend on the irradiation
energy. In addition, shadowing effects similar to those found in oblique-angle growth of thin films were seen.
Reliable quantification of the transition from the sp2-bonding to sp3-hybridized state as a result of Ar+ ion irradiation
is achieved from the deconvolution of the XPS C (1s) peak. Although the ion irradiation effect is demonstrated
through the shape of the derivative of the Auger transition C KVV spectra, we show that the D parameter values
obtained from these spectra which are normally used in the literature fail to account for the sp2 to sp3 hybridization
transition. In contrast to what is known, it is revealed that using ion irradiation at large FLG sample tilt angles can
lead to edge reconstructions. Furthermore, FLG irradiation by low energy of 0.25 keV can be a plausible way of
peeling graphene layers without the need of Joule heating reported previously |
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