TIBERJ Antoine
Organisme : Université Montpellier II
Maître de Conférences
Autre(s) thème(s) de recherche ou rattachement(s) : - Composants et capteurs
Antoine.Tiberj
univ-montp2.fr
0467143794
Bureau: 37.1, Etg: 2, Bât: 21 - Site : Campus Triolet
Administration Locale:- Membre d'un pool d'experts
|
Domaines de Recherche: - Physique/Matière Condensée/Science des matériaux
|
Dernieres productions scientifiques :
|
|
Reversible Optical Doping of graphene 
Auteur(s): TIBERJ A. , Rubio-roy Miguel, PAILLET M., HUNTZINGER J.-R., LANDOIS P., Mikolasek Mirko, CONTRERAS S., SAUVAJOL J.-L., Dujardin Erik, ZAHAB A. A.
Conférence invité: GDR-I GNT 2013 (Guidel-Plages, Lorient, FR, 2013-04-08)
Ref HAL: hal-00813854_v1
Résumé: The ultimate surface exposure provided by graphene monolayer makes it the ideal sensor platform but also exposes its intrinsic properties to any environmental perturbations. We show in this work that structural and electronic characterization of graphene in air by Raman spectroscopy is significantly affected by the substrate surface cleaning method and moderate laser power conditions. In particular, we demonstrate that the charge carrier density of graphene exfoliated on a SiO2/Si substrate can be finely and reversibly tuned between electron and hole doping with visible photons. The amplitude of this photo-induced doping is found to require hydrophilic substrates and to vanish in suspended graphene. These findings suggest that optically gated graphene devices operating with a sub-second time scale can be envisioned but also that Raman spectroscopy might not be as non-invasive as generally assumed.
|
|
|
|
In Situ Raman Probing of Graphene over a Broad Doping Range upon Rubidium Vapor Exposure
Auteur(s): PARRET R., PAILLET M., HUNTZINGER J.-R., NAKABAYASHI D., MICHEL T., TIBERJ A., SAUVAJOL J.-L., ZAHAB A. A.
(Article) Publié:
ACS Nano, vol. 7 p.165 (2013)
Ref HAL: hal-00785831_v1
DOI: 10.1021/nn3048878
Résumé: We report in situ Raman scattering experiments on single-layer graphene (SLG) and Bernal bilayer graphene (BLG) during exposure to rubidium vapor. The G- and 2D-band evolutions with doping time are presented and analyzed. On SLG, the extended doping range scanned (up to about 1014 electrons/cm2) allows the observation of three regimes in the evolution of the G-band frequency: a continuous upshift followed by a plateau and a downshift. Overall the measured evolution is interpreted as the signature of the competition between dynamic and adiabatic effects upon n-doping. Comparison of the obtained results with theoretical predictions indicates however that a substrate pinning effect occurs and inhibits charge-induced lattice expansion of SLG. At low doping, a direct link between electrostatic gating and Rb doping results is presented. For BLG, the added electrons are shown to be first confined in the top layer, but the system evolves with time toward a more symmetric repartition of the added electrons in both layers. The results obtained on BLG also confirm that the slope of the phonon dispersion close to the K point tends to be slightly reduced at low doping but suggest the occurrence of an unexpected increase of the phonon dispersion slope at higher electron concentration.
|
|
|
|
Raman Imaging in Semiconductor Physics: Applications to Microelectronic Materials and Devices
Auteur(s): TIBERJ A., CAMASSEL J.
Chapître d'ouvrage: Raman Imaging Techniques and Applications, vol. p.ISBN: 978-3-642-28251-5 (2012)
Ref HAL: hal-00803592_v1
DOI: 10.1007/978-3-642-28252-2
Résumé: The unique versatility of micro-Raman spectroscopy (μRS) in semicon- ductor physics remains in Raman imaging. Numerous applications cover the whole development of modern electronic and optoelectronic devices: from semiconduc- tor growth to advanced device inspection tools. In this chapter, a wide variety of semiconductors (SiC, graphene, GaN, GaAs, SiGe, strained Si, sSOI, SGOI) and devices (FETs, lasers, MEMS) are addressed. First, it will be shown how Raman mapping enables to check the crystalline quality, the composition, the doping, and the uniformity of as-grown semiconductors. Then, we will focus on the most popular application in microelectronics: strain measurements either at the device or at the full wafer scale. Finally, we will show how μRS imaging can be used for final device inspection through the temperature mapping of operating devices (FETs, lasers, actuators).
|
|
|
|
Raman spectroscopy of epitaxial graphene
Auteur(s): TIBERJ A., HUNTZINGER J.-R., PAILLET M., ZAHAB A. A., CONTRERAS S., CAMASSEL J., SAUVAJOL J.-L., Camara N., Caboni Alessandra, Godignon Philipe
(Affiches/Poster)
GDRI GNT 2012 (Lyon, FR), 2012-01-24
Résumé: The Raman bands intensities, frequencies, widths and profiles of few layer graphene (FLG) are extremely sensitive to doping, strain, stacking order, number of graphene sheets, crystalline quality and laser wavelength. For samples of epitaxial graphene grown on silicon carbide, the laser wavelength is basically the only factor known a priori. Furthermore, the concomitance of second order SiC Raman modes in the graphene G and D bands region complicates the extraction of the graphene signal. Developing a robust characterization tool enabling to disentangle all these effects and to provide reliable information is thus highly needed and challenging. We propose an approach where micro-Raman spectroscopy is combined with reflectivity and transmission measurements
to discriminate between the different contributions in the measured Raman signatures and to access to the detailed characteristics of the samples. Here, we demonstrate the efficiency of this method in order to determine the number of graphene layers. We address then the question of using the 2D band width or ratio of the 2D and G bands intensities as a criteria to distinguish between mono and multi layer(s) graphene.
|
|
|
|
Micro-Raman and micro-transmission studies of Graphene on 6H-SiC
Auteur(s): TIBERJ A., HUNTZINGER J.-R., Camara N., Godignon Philipe, CAMASSEL J.
Conférence invité: Epigraphic Workshop on the Science and Applications of Epitaxial Graphene on SiC (Catania, IT, 2012-12-04)
Ref HAL: hal-00803575_v1
Résumé: A detailed comparison of true epitaxial graphene monolayers grown on both faces of 6H SiC substrates (Si and C faces) is made by combining micro-Raman spectroscopy with transmission measurements. We have already shown that such combination allows to discriminate without any ambiguity between a graphene monolayer and a twisted or folded graphene bilayer (AA') grown on the C face of 6H SiC [1]. In this presentation, we will focus on the Raman spectra and the transmission measurements performed on graphene monolayers grown on the Si face of 6H SiC. The graphene growth was tuned to get a mixed surface at the early stage of graphitization with i) bare SiC, ii) buffer layer and iii) in some localized areas small monolayers flakes on top of the buffer layer. These unique samples enabled to measure properly the Raman spectrum of the buffer layer (carbon layer with a large number of sp3 bonds) and its optical extinction at 514.5 nm. The Raman spectrum of this buffer layer remains visible after the growth of one monolayer on top but the Raman intensity is strongly reduced (typically divided by a factor of 3). This cannot be attributed to the absorption coefficient of graphene which is relatively low (few percents). Finally, several Raman mapping reveal the uniformity of the graphene monolayers in terms of thickness and crystalline quality, but also that they are subjected to a non uniform compressive strain.
|
Plus...
