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International audience; Graphene is a remarkable two-dimensional (2D) material that is of great interest to both academia and industry. Several methods are used to produce either pristine graphene or doped graphene. Among these methods, Pulse Laser Deposition (PLD) has proved to be an alternative route for producing graphene layers from amorphous carbon thin films, due to many advantages including the controlled film thickness and dopant compositions in the films [1]. The present talk will review the ability of PLD to produce graphene and doped graphene films, mainly with nitrogen or boron atoms [2]. The growth mechanism will be highlighted on the basis of XPS investigations in situ during graphene growth. The film characteristics depending on the synthesis process are discussed mainly on the basis of Raman and XPS/AES investigations. Exploration of some electrical conduction properties are emphasized. In particular, electroanalytical experiments show that functionalized electrodes with nitrogen-doped graphene from PLD exhibits excellent reversibility, close to the theoretical value of 59 mV, and very high sensitivity to hydrogen peroxide oxidation [3]. The electroanalytical results were correlated with the composition and nanoarchitecture of the N-doped graphene film identified as a few-layer defected and textured graphene film containing a balanced mixture of graphitic-N and pyrrolic-N chemical functions. The present talk will help researchers to have an overview of the interest of PLD for graphene and doped-graphene synthesis.

International audience; In recent years, the research on graphene has received a lot of interest to both academia and industry due to its outstanding physical and chemical properties, and its potential for various applications. Due to this, several methods are used to produce either pristine graphene or doped graphene. Among these methods, Pulsed Laser Deposition (PLD) has proved to be an alternative route for producing graphene layers from amorphous carbon thin films, due to many advantages including the controlled film thickness and dopant compositions in the films [1]. The present talk will give an overview of the ability of PLD to fabricate graphene and doped graphene films, mainly with nitrogen or boron atoms [2]. The growth mechanism will be highlighted based on XPS investigations in situ during graphene growth. The graphene films characteristics depending on the substrates and the influence of synthesis process parameters such as initial amorphous carbon (a-C) thickness, laser energy and annealing temperature on the growth of graphene are discussed mainly based on Raman analysis. Investigations of electrochemistry properties of nitrogen-doped graphene synthesized by PLD are emphasized. The results show that functionalized electrodes with nitrogen-doped graphene exhibit excellent reversibility, close to the theoretical value of 59 mV, and very high sensitivity to hydrogen peroxide oxidation [3]. The present talk will help researchers to get an overview of the interest of PLD for graphene and doped-graphene synthesis.References1.Y. Bleu, F. Bourquard, T. Tite, A.-S. Loir, C. Maddi, C. Donnet, F. Garrelie, Frontier in Chemistry, 2018, 6, 572.2.C. Maddi, F. Bourquard, V. Barnier, J. Avila, M.-C. Asensio, T. Tite, C Donnet, F. Garrelie, Scientific Reports, 2018, 8, 3247.3.F. Bourquard, Y. Bleu, A.-S. Loir, B. Caja-Munoz, J. Avila, M.-C. Asensio, G. Raimondi, M. Shokouhi, I. Rassas, C. Farre, C. Chaix, V. Barnier, N. Jaffrezic-Renault, F. Garrelie, C. Donnet, Materials, 2019, 12, 666.

International audience; applications such as nanoelectronics, nanophotonics, sensor devices and green energy technology. One way consists in thermal heating of a doped solid carbon source, such as an amorphous a-C:N film, in the presence of a metal catalyst, to obtain nitrogenated graphene (NG) layers. The control of such a process requires to investigate diffusion and segregation mechanisms of the graphene precursor through the metal catalyst.In the present study, the mechanism of atomic diffusion and NG film growth through a nickel catalyst thin film was investigated using in situ X-ray photoelectron spectroscopy (XPS) performed during thermal heating responsible for NG synthesis. Amorphous a-C:N films, containing 16%at. nitrogen, 10 nm thick, were synthetized by femtosecond pulsed laser ablation on fused silica substrates. A 150 nm thick nickel film was subsequently deposited by thermal evaporation on the a-C:N films. Thermal annealing at various temperatures (200, 300, 500 and 650°C), with different time durations, were performed in ultra-high vacuum during in situ XPS analysis, to carry out the top surface genesis of the NG film onto the nickel catalyst. FEG-SEM, Raman and X-ray absorption (XAS) spectroscopies were also performed to elucidate the nature and chemical composition of NG films. The diffusion of carbon and nitrogen through the nickel film towards the surface from 300°C was observed, without any graphene signature. Graphene films are formed at the highest temperatures, with a final 3%at. nitrogen content, in both pyrrolic and pyridinic configurations. The solid-state transformation mechanism responsible for the formation of few-layer NG films is thus investigated. The kinetics of carbon surface enrichment observed using in-situ XPS is discussed in the frame of the interface segregation theory and modelled using the du Plessis approach.

Resumen del póster presentado al 10th International Symposium on Metallic Multilayers (MML), celebrado en Madrid (España) del 17 al 21 de junio de 2019., We have explored the realization of trilayer structures with single layer Graphene spacers and antiferromagnetically exchange coupled ferromagnetic layers, i.e. FM/Gr/FM, with close to zero net magnetization configurations. Studied systems were in-situ prepared via molecular-beam epitaxy in combination with intercalation procedures, to exchange couple ferromagnetic layers (Co, Fe, Ni) through a Graphene single layer spacer obtained by CVD on a Ir(111) surface. Alternatively, we have explored the possibility of fabricating a related system by incomplete intercalation, which yields interesting results for the case of Gr CVD on sputtered Pt on a sapphire single crystal. Our results provide an experimental demonstration of perpendicular antiferromagnetic exchange coupling of two Cobalt layers across a Graphene single spacing layer, as recently predicted and extending previous results. Furthermore, this constitutes a first step towards the engineering of compensated Graphene-based synthetic antiferromagnetic structures and nanostructures, which display close to zeronet macroscopic magnetization configurations that appear interesting for fundamental studies and may enclose potential for applications. Details on the surface preparation and investigation on these hybrid magnetic/Graphene heterostructures using soft x-ray absorption spectroscopy and magnetic dichroism measurements performed at ALBA synchrotron will be presented., This work was supported by Mineco “Retos program” under grants FIS2013-45469-C4- 3-R, FIS2016-78591- C3 (AEI/FEDER, UE), MAT2014-59315-R, and additionally GenCat 2014SGR301, H2020 EINFRA-2015-1 676598 and Marie Skłodoswa-Curie no. 665919.

Resumen del trabajo presentado al 10th International Symposium on Metallic Multilayers (MML), celebrado en Madrid (España) del 17 al 21 de junio de 2019., This work was supported by Mineco “Retos program” under grants FIS2013-45469-C4- 3-R, FIS2016-78591- C3 (AEI/FEDER, UE), MAT2014-59315-R, and additionally GenCat 2014SGR301, H2020 EINFRA-2015-1 676598 and Marie Skłodoswa-Curie no. 665919.

International audience; This study reports the comparative investigation of graphene films prepared on Si (100) and SiO2 by combining pulsed laser deposition and rapid thermal annealing using Ni catalyst. The effect of substrate and growth temperatures (600-1000°C) on the formation of graphene films was investigated by Raman spectroscopy, mapping and scanning electron microscopy (SEM). It was found that graphene films formed on Si (100) is multilayered with the formation of various nickel silicides depending on the growth temperature, while graphene films prepared on SiO2 are predominant bi- and trilayered graphene with no nickel silicide formation. The analysis of the Raman D, G and 2D peaks intensities and positions as a function of the growth temperature showed a complete opposite evolution between Si (100) and SiO2 substrates. These findings contribute to a better understanding of the combination between the nature of the substrate and the growth temperature, when growing graphene films from solid carbon source with nickel catalyst on both Si(100) and SiO2 substrates. Such a good comprehension of the substrate impact is vital for potential applications and device fabrication of graphene.

International audience; The introduction of dopants, such as boron, into the graphene network, is essential for many applications (electrochemistry, sensors, photovoltaics, catalysis, etc.). Many preparation routes have been investigated for B-doped graphene (BG) films: CVD, chemical reactions between graphene or graphene oxide with boron precursors, hydrothermal and solvothermal processes, arc discharge, high temperature sublimation of highly B-doped SiC and B4C thermal decomposition. Another way consists in pulsed laser co-ablation of C and B solid sources followed by rapid thermal heating of the B-doped carbon film deposited on a metal catalyst, to obtain BG layers. The objective is to achieve a better control of boron concentration in the films.Here, we use for the first time pulsed laser co-ablation for the synthesis of B-doped graphene layers. Amorphous a-C:B films, containing 2%at. boron, 10 nm thick, are synthetized by nanosecond pulsed laser deposition on a Ni thin film (60 nm thick) previously deposited on a SiO2 substrate. Rapid Thermal Annealing is performed at 1100°C during 2’ with a heating rate of 15°C/s and a cooling rate of 1°C/s. Raman, XPS, FEG-SEM and AFM characterizations allow to determine the nature, composition and morphology of the BG films. The results confirm the fabrication of bi-trilayers boron doped graphene films with the same boron doping level (2%at) as the starting material. Our results pave a new way for boron doped graphene synthesis using laser processing.