Ion irradiation by 500 keV C(+) ions has been used to introduce defects into graphene sheets deposited on SiO(2) in a controlled way. The combined use of Raman spectroscopy and atomic force microscopy (AFM) allowed one to clarify the mechanisms of disorder formation in single layers, bilayers and multi-layers of graphene. The ratio between the D and G peak intensities in the Raman spectra of single layers is higher than for bilayers and multi-layers, indicating a higher amount of disorder. This cannot be only ascribed to point defects, originating from direct C(+)-C collisions, but also the different interactions of single layers and few layers with the substrate plays a crucial role. As demonstrated by AFM, for irradiation at fluences higher than 5 x 10(13) cm(-2), the morphology of single layers becomes fully conformed to that of the SiO(2) substrate, i.e. graphene ripples are completely suppressed, while ripples are still present on bilayer and multi-layers. The stronger interaction of a single layer with the substrate roughness leads to the observed larger amount of disorder. (C) 2009 Elsevier Ltd. All rights reserved.

Ion irradiation and defect formation in single layer graphene

COMPAGNINI, Giuseppe Romano;
2009-01-01

Abstract

Ion irradiation by 500 keV C(+) ions has been used to introduce defects into graphene sheets deposited on SiO(2) in a controlled way. The combined use of Raman spectroscopy and atomic force microscopy (AFM) allowed one to clarify the mechanisms of disorder formation in single layers, bilayers and multi-layers of graphene. The ratio between the D and G peak intensities in the Raman spectra of single layers is higher than for bilayers and multi-layers, indicating a higher amount of disorder. This cannot be only ascribed to point defects, originating from direct C(+)-C collisions, but also the different interactions of single layers and few layers with the substrate plays a crucial role. As demonstrated by AFM, for irradiation at fluences higher than 5 x 10(13) cm(-2), the morphology of single layers becomes fully conformed to that of the SiO(2) substrate, i.e. graphene ripples are completely suppressed, while ripples are still present on bilayer and multi-layers. The stronger interaction of a single layer with the substrate roughness leads to the observed larger amount of disorder. (C) 2009 Elsevier Ltd. All rights reserved.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.11769/11564
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