Showing papers by "Cinzia Casiraghi published in 2012"
TL;DR: A detailed analysis of the Raman spectra of graphene containing different type of defects is presented, finding that the intensity ratio of the D and D' peak is maximum for sp(3)-defects, it decreases for vacancy-like defects, and it reaches a minimum for boundaries in graphite.
Abstract: Raman spectroscopy is able to probe disorder in graphene through defect-activated peaks. It is of great interest to link these features to the nature of disorder. Here we present a detailed analysis of the Raman spectra of graphene containing different type of defects. We found that the intensity ratio of the D and D′ peak is maximum (∼13) for sp3-defects, it decreases for vacancy-like defects (∼7), and it reaches a minimum for boundaries in graphite (∼3.5). This makes Raman Spectroscopy a powerful tool to fully characterize graphene.
1,716 citations
TL;DR: Graphene bubbles are used to study the Raman spectrum of graphene under biaxial (e.g., isotropic) strain and the Gruneisen parameters are in excellent agreement with the theoretical values.
Abstract: We use graphene bubbles to study the Raman spectrum of graphene under biaxial (e.g., isotropic) strain. Our Gruneisen parameters are in excellent agreement with the theoretical values. Discrepancy in the previously reported values is attributed to the interaction of graphene with the substrate. Bilayer balloons (intentionally pressurized membranes) have been used to avoid the effect of the substrate and to study the dependence of strain on the interlayer interactions.
473 citations
TL;DR: It is reported that boron atoms can be efficiently substituted for carbon in graphene and Boron-doped graphene appears to be a useful tool for engineering the physical and chemical properties of graphene.
Abstract: The introduction of foreign atoms, such as nitrogen, into the hexagonal network of an sp2-hybridized carbon atom monolayer has been demonstrated and constitutes an effective tool for tailoring the intrinsic properties of graphene. Here, we report that boron atoms can be efficiently substituted for carbon in graphene. Single-layer graphene substitutionally doped with boron was prepared by the mechanical exfoliation of boron-doped graphite. X-ray photoelectron spectroscopy demonstrated that the amount of substitutional boron in graphite was ∼0.22 atom %. Raman spectroscopy demonstrated that the boron atoms were spaced 4.76 nm apart in single-layer graphene. The 7-fold higher intensity of the D-band when compared to the G-band was explained by the elastically scattered photoexcited electrons by boron atoms before emitting a phonon. The frequency of the G-band in single-layer substitutionally boron-doped graphene was unchanged, which could be explained by the p-type boron doping (stiffening) counteracting the...
233 citations
12 Jul 2012
TL;DR: In this paper, the authors show that Raman Spectroscopy is a very powerful tool for the investigation of graphene, being very sensitive to phonons, electronic states, defects and to the interaction between the fundamental excitations of graphene.
Abstract: Graphene attracts enormous interest because of its unique properties. Giant intrinsic charge mobility at room temperature makes it a potential material for nano-electronics. Its optical and mechanical properties are ideal for micro- and nano-mechanical systems, thin-film transistors, transparent and conductive composites, electrodes and for photonics. This Chapter will show that Raman Spectroscopy is a very powerful tool for the investigation of graphene, being very sensitive to phonons, electronic states, defects and to the interaction between the fundamental excitations of graphene.
62 citations
TL;DR: In this paper, the authors used graphene bubbles to study the Raman spectrum of graphene under biaxial (e.g. isotropic) strain and the results were in excellent agreement with the theoretical values.
Abstract: In this letter we use graphene bubbles to study the Raman spectrum of graphene under biaxial (e.g. isotropic) strain. Our Gruneisen parameters are in excellent agreement with the theoretical values. Discrepancy in the previously reported values is attributed to the interaction of graphene with the substrate. Bilayer balloons (intentionally pressurized membranes) have been used to avoid the effect of the substrate and to study the dependence of strain on the inter-layer interactions.