scispace - formally typeset
Search or ask a question

Showing papers by "Cinzia Casiraghi published in 2008"


Journal ArticleDOI
TL;DR: In this article, the position, width and intensity of G and D peaks at the edges are studied as a function of the incident light polarization, and the D-band is strongest for light polarized parallel to the edge and minimum for perpendicular orientation.
Abstract: Graphene edges are of particular interest, since their chirality determines the electronic properties. Here we present a detailed Raman investigation of graphene flakes with well defined edges oriented at different crystallographic directions. The position, width and intensity of G and D peaks at the edges are studied as a function of the incident light polarization. The D-band is strongest for light polarized parallel to the edge and minimum for perpendicular orientation. Raman mapping shows that the D peak is localized in proximity of the edge. The D to G ratio does not always show a significant dependence on edge orientation. Thus, even though edges can appear macroscopically smooth and oriented at well defined angles, they are not necessarily microscopically ordered.

744 citations


Journal ArticleDOI
TL;DR: In this paper, structural and electrical conduction properties of nitrogen-doped nanocrystalline diamond films are studied as a function of deposition temperature (TD) in a microwave Ar-rich/CH4 plasma with 30% N2 addition.
Abstract: Structural and electrical conduction properties of nitrogen-doped nanocrystalline diamond films are studied as a function of deposition temperature (TD) in a microwave Ar-rich/CH4 plasma with 30%N2 addition. Hall- and Seebeck-effect measurements confirm n-type conduction for TD above 1100 K. For TD from 1100 and 1220 K, the electron concentration increases up to 1020 cm−3 and the electron mobility is in the range of 4–8 cm2 V−1 s−1. For TD above 1250 K, the mobility decreases to ∼1 cm2 V−1 s−1. Low conductivity films deposited at low TD exhibit semiconductorlike thermal activation in the Arrhenius plots, while high conductivity films deposited at high TD are almost temperature independent, indicative of quasimetallic conduction. The nitrogen concentration in the films is about 0.3 at. %, independent of TD. As TD is increased, the sp2 content and order increase. This is responsible for the appearance of midgap states, their delocalization, and the larger distance between diamond grains. The high conductivi...

83 citations


Journal ArticleDOI
TL;DR: In this article, the thermal conductivity of ultrathin tetrahedral amorphous carbon (ta-C) films on silicon, down to subnanometer thickness, was investigated.
Abstract: We investigate the thermal conductivity of ultrathin tetrahedral amorphous carbon (ta-C) films on silicon, down to subnanometer thickness. For films with an initial sp3 content of 60%, the thermal conductivity reduces from 1.42to0.09W∕mK near room temperature as the thickness decreases from 18.5to∼1nm. The variation in ta-C film thickness is accompanied by changes in Young’s modulus, density, and sp3 content. The thermal resistance of the finite-thickness interface layer, which forms between ta-C and silicon, is ∼10−8m2K∕W near room temperature, thus producing a noticeable effect on thermal transport in ultrathin ta-C films.

76 citations


Journal ArticleDOI
TL;DR: In this article, the use of ultrathin diamond-like carbon (DLC) films for ultrahigh-density data storage in magnetic and optical disks and ultralong beer storage in plastic bottles is discussed.
Abstract: Carbon is a very versatile element that can crystallize in the forms of diamond or graphite. There are many noncrystalline carbons, known as amorphous carbons. An amorphous carbon with a high fraction of diamond-like (sp3) bonds is named diamond-like carbon (DLC). Unlike diamond, DLC can be deposited at room temperature. Furthermore, its properties can be tuned by changing the sp3 content, the organization of the sp2 sites, and the hydrogen content. This makes DLC ideal for a variety of different applications. We review the use of ultrathin DLC films for ultrahigh-density data storage in magnetic and optical disks and ultralong beer storage in plastic bottles.

43 citations


Journal ArticleDOI
TL;DR: In this paper, electrical transport and Raman measurements on individual single-wall carbon nanotubes filled with the paramagnetic metallofullerene Sc@C82 were performed.
Abstract: We present electrical transport and Raman measurements on individual single-wall carbon nanotubes filled with the paramagnetic metallofullerene Sc@C82. We find nearly all devices to be metallic p-type conductors, which we tentatively attribute to bandstructure modification of the nanotubes by the encapsulated Sc@C82 molecules. At low temperatures the peapod devices behave as quantum dots and transport is shown to be quantum coherent over distances of at least ∼100 nm. Kondo features are observed at the lowest measurement temperatures of 50 mK. Our results are of fundamental interest because of the long spin coherence times of the unpaired electrons on the Sc@C82 molecules and the possibility this offers for studying one-dimensional spin chains in carbon nanotubes.

10 citations