Publications

2013

• Advanced Mueller Ellipsometry Instrumentation and Data Analysis.
  
  • Garcia-Caurel Enric
  • Ossikovski Razvigor
  • Foldyna Martin
  • Pierangelo Angelo
  • de Martino Antonello
  • Drévillon Bernard
  , 2013, pp.31. The main object of this chapter is to give an overview the possibilities offered by instruments capable of measuring full Mueller matrices in the field of optical characterization. We have chosen to call these instruments Mueller ellipsometers in order to highlight their close relation with instruments traditionally used in ellipsometry. We want to make clear to the reader the place that Mueller ellipsometry takes with respect to standard ellipsometry by showing the similarities but also the differences among these techniques, both in instrumentation and data treatment. To do so the chapter starts by a review of the optical formalisms used in standard and Mueller ellipsometry respectively. In order to highlight the particularities and the advantages brought by Mueller ellipsometry, a special section is devoted to the algebraic properties of Mueller matrices and to the description of different ways to decompose them. Matrix decompositions are used to unveil the basic polarimetric properties of a the sample when a precise model is not available. Then follows a description of the most common optical configurations used to build standard ellipsometers. Special attention is paid to show what can and what cannot be measured with them. On the basis of this knowledge it is shown the interest of measuring whole Mueller matrices, in particular for samples characterized by complex anisotropy and/or depolarization. Among the numerous optical assemblies able to measure full Mueller matrices, most of them are laboratory prototypes, and only very few have been industrialized so far. Because an extensive and comparative review of all the Mueller ellipsometric instruments developed to date is clearly out of the scope of this chapter, we limit our description to four Mueller ellipsometers, two imaging and two spectroscopic systems that have been developed by us in the past years. The technical description of the Mueller ellipsometers is accompanied by some examples of applications which, without being exhaustive, are representative of the type of analyses performed in ellipsometry, and also illustrate the advantages that can be brought by modern Mueller ellipsometers to optical metrology, materials science and biomedicine
• Copolythiophene-based water-gated organic field-effect transistors for biosensing
  
  • Suspène Clément
  • Piro Benoît
  • Reisberg Steve
  • Pham Minh Chau
  • Toss Henrik
  • Berggren Magnus
  • Yassar Abderrahim
  • Horowitz Gilles
  Journal of materials chemistry‎ B, Royal Society of Chemistry, 2013, 1 (15), pp.2090-2097. This paper reports on the sensing of proteins using water-gated organic field-effect transistors. As a proof-of-concept, streptavidin and avidin were used, with a biotinylated polymer as the active sensing material. The latter is a copolythiophene modified to graft biotin by peptidic coupling. After characterization of its structure, it was integrated as the channel material into transistors and its interactions with several proteins were investigated. Non-specific interactions were reduced when the polymer surface was pretreated with 1-octanol. In this case, human serum albumin had no effect on the transistor characteristics whereas avidin and streptavidin led to a decrease of the drain current. (10.1039/C3TB00525A)
  DOI : 10.1039/C3TB00525A
• Enhanced sensitivity to dielectric function and thickness of absorbing thin films by combining total internal reflection ellipsometry with standard ellipsometry and reflectometry
  
  • Lizana Angel
  • Foldyna Martin
  • Stchakovsky Michel
  • Georges Benoit
  • David Nicolas
  • Garcia-Caurel Enric
  Journal of Physics D: Applied Physics, IOP Publishing, 2013, 46 (10), pp.105501. High sensitivity of spectroscopic ellipsometry and reflectometry for the characterization of thin films can strongly decrease when layers, typically metals, absorb a significant fraction of the light. In this paper, we propose a solution to overcome this drawback using total internal reflection ellipsometry (TIRE) and exciting a surface longitudinal wave: a plasmon-polariton. As in the attenuated total reflectance technique, TIRE exploits a minimum in the intensity of reflected transversal magnetic (TM) polarized light and enhances the sensitivity of standard methods to thicknesses of absorbing films. Samples under study were stacks of three films, ZnO : Al/Ag/ZnO : Al, deposited on glass substrates. The thickness of the silver layer varied from sample to sample. We performed measurements with a UV-visible phase-modulated ellipsometer, an IR Mueller ellipsometer and a UV-NIR reflectometer. We used the variance-covariance formalism to evaluate the sensitivity of the ellipsometric data to different parameters of the optical model. Results have shown that using TIRE doubled the sensitivity to the silver layer thickness when compared with the standard ellipsometry. Moreover, the thickness of the ZnO : Al layer below the silver layer can be reliably quantified, unlike for the fit of the standard ellipsometry data, which is limited by the absorption of the silver layer. (10.1088/0022-3727/46/10/105501)
  DOI : 10.1088/0022-3727/46/10/105501
• Nouveau Métallopolymères et leur utilisation
  
  • Zucchi Gaël
  • Sergent Alessandra
  • Tondelier Denis
  • Geffroy Bernard
  , 2013.
• Interphase chemistry of Si electrodes used as anodes in Li-ion batteries
  
  • Pereira-Nabais Catarina
  • Swiatowska Jolanta
  • Chagnes Alexandre
  • Ozanam Francois
  • Gohier Aurelien
  • Tran-Van Pierre
  • Cojocaru Costel Sorin
  • Cassir Michel
  • Marcus Phillipe
  Applied Surface Science, Elsevier, 2013, 266, pp.5-16. The effect of the Si electrode morphology (amorphous hydrogenated silicon thin films - a-Si:H as a model electrode and Si nanowires - SiNWs electrode) on the interphase chemistry was thoroughly investigated by the surface science techniques: X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). XPS analysis shows a strong attenuation and positive shift of the Si 2p peaks after a complete charge/discharge performed in PC- and EC:DMC-based electrolytes for both electrodes (a-Si:H and SiNW), confirming a formation of a passive film (called solid electrolyte interphase - SEI layer). As evidenced from the XPS analysis performed on the model electrode, the thicker SEI layer was formed after cycling in PC-based electrolyte as compared to EC:DMC electrolyte. XPS and ToF-SIMS investigations reveal the presence of organic carbonate species on the outer surface and inorganic salt decomposition species in the inner part of the SEI layer. Significant modification of the surface morphol- ogy for the both electrodes and a full surface coverage by the SEI layer was confirmed by the scanning electron microscopy (SEM) analysis. (10.1016/j.apsusc.2012.10.165)
  DOI : 10.1016/j.apsusc.2012.10.165
• Benzofuran-fused Phosphole: Synthesis, Electronic, and Electroluminescence Properties
  
  • Chen Hui
  • Delaunay Wylliam
  • Li Jing
  • Wang Zuoyong
  • Bouit Pierre-Antoine
  • Tondelier Denis
  • Geffroy Bernard
  • Mathey François
  • Duan Zheng
  • Réau Régis
  • Hissler M.
  Organic Letters, American Chemical Society, 2013, 15 (2), pp.330-333. A synthetic route to novel benzofuran-fused phosphole derivatives 3-5 is described. These compounds showed optical and electrochemical properties that differ from their benzothiophene analog. Preliminary results show that 4 can be used as an emitter in OLEDs, illustrating the potential of these new compounds for opto-electronic applications. (10.1021/ol303260d)
  DOI : 10.1021/ol303260d
• Modélisation physique et compacte de transistors en couches minces à base de silicium amorphe ou microcristallin
  
  • Jin Jong Woo
  , 2013. Dans le but de développer un modèle compact spécifique aux transistors en couches minces (TFT) à base de silicium amorphe ou microcristallin, nous présentons dans ce manuscrit nos études sur l'optimisation des modèles compacts et des méthodes d'extraction des paramètres et, surtout, différents phénomènes présents dans la physique de ces TFTs. Nous proposons une méthode plus robuste d'extraction des paramètres, qui, différemment des méthodes conventionnelles, ne néglige pas la résistance d'accès, diminuant ainsi la subjectivité du procédé de l'extraction. La résistance d'accès dans les différentes structures a été analysée. Pour la structure top-gate coplanar, nous nous sommes focalisés sur des raisons géométriques pour montrer la dépendance de la résistance d'accès en tension de grille. Pour la structure bottom-gate staggered, nous avons introduit l'approche de transport-diffusion au modèle de current crowding, en prouvant la dépendance en tension de grille et en courant en raison de la diffusion des électrons. Le comportement dynamique a été étudié en couplant mesures expérimentales et simulations par éléments finis, en associant les capacités intrinsèques des TFTs avec le temps de retard d'allumage. Nous avons observé l'évolution temporelle du canal lors de sa création ou de sa disparition et nous avons ainsi proposé un modèle qui décrit sa propagation dans un TFT. Nous avons enfin étudié le phénomène de vieillissement des TFTs et nous avons mis en évidence la localisation de la dégradation et de la relaxation dans un TFT sous un stress électrique avec la tension de drain non-nulle.
• Focal Point Review - Application of Spectroscopic Ellipsometry and Mueller Ellipsometry to Optical Characterization
  
  • Garcia-Caurel Enric
  • de Martino Antonello
  • Gaston Jean-Paul
  • Yan Li
  Applied Spectroscopy, Society for Applied Spectroscopy, 2013, 67 (1), pp.1. This article aims to provide a brief overview of both established and novel ellipsometry techniques, as well as their applications. Ellipsometry is an indirect optical technique in that information about the physical properties of a sample is obtained through modeling analysis. Standard ellipsometry is typically used to characterize optically isotropic bulk and/or layered materials. More advanced techniques like Mueller ellipsometry, also known as polarimetry in literature, are necessary for the complete and accurate characterization of anisotropic and/or depolarizing samples which occur in many instances, both in research and "real life" activities. In this article we cover three main areas of subject: basic theory of polarization, standard ellipsometry and Mueller ellipsometry. Section I is devoted to a short and pedagogical introduction of the formalisms used to describe light polarization. The following section is devoted to standard ellipsometry. The focus is on the experimental aspects, including both pros and cons of commercially available instruments. Section III is devoted to recent advances in Mueller ellipsometry. Applications examples are provided in sections II and III to illustrate how each technique works. (10.1366/12-06883)
  DOI : 10.1366/12-06883
• White organic light-emitting diodes with an ultra-thin premixed emitting layer
  
  • Jeon T.
  • Geffroy Bernard
  • Tondelier Denis
  • Bonnassieux Yvan
  • Forget Sebastien
  • Chenais Sebastien
  • Ishow Eléna
  Thin Solid Films, Elsevier, 2013, 542, pp.263-269. We described an approach to achieve fine color control of fluorescent White Organic Light-Emitting Diodes (OLED), based on an Ultra-thin Premixed emitting Layer (UPL). The UPL consists of a mixture of two dyes (red-emitting 4-di(4′-tert-butylbiphenyl-4-yl)amino-4′-dicyanovinylbenzene or fvin and green-emitting 4-di(4′-tert-butylbiphenyl-4-yl)aminobenzaldehyde or fcho) premixed in a single evaporation cell: since these two molecules have comparable structures and similar melting temperatures, a blend can be evaporated, giving rise to thin films of identical and reproducible composition compared to those of the pre-mixture. The principle of fine color tuning is demonstrated by evaporating a 1-nm-thick layer of this blend within the hole-transport layer (4,4′-bis[N-(1-naphtyl)-N-phenylamino]biphenyl (α-NPB)) of a standard fluorescent OLED structure. Upon playing on the position of the UPL inside the hole-transport layer, as well as on the premix composition, two independent parameters are available to finely control the emitted color. Combined with blue emission from the heterojunction, white light with Commission Internationale de l'Eclairage 1931 color coordinates (0.34, 0.34) was obtained, with excellent color stability with the injected current. The spectrum reveals that the fcho material does not emit light due to efficient energy transfer to the red-emitting fvin compound but plays the role of a host matrix for fvin, allowing for a very precise adjustment of the red dopant amount in the device. (10.1016/j.tsf.2013.06.054)
  DOI : 10.1016/j.tsf.2013.06.054
• Doped semiconductor nanocrystal junctions studied by Kelvin probe and non-contact atomic force microscopy
  
  • Borowik Lukasz
  • Nguyen-Tran Thuat
  • Deresmes D.
  • Diesinger Heinrich
  • Roca I Cabarrocas Pere
  • Melin Thierry
  , 2013. Semiconductor junctions are the basis of electronic and photovoltaic devices. Here, we investigate junctions formed from highly doped (ND~10^20-10^21 cm-3) hydrogen-passivated silicon nanocrystals (NCs) in the 2-50nm size range, using non-contact atomic force microscopy coupled to Kelvin probe force microscopy experiments with single charge sensitivity, in ultra-high vacuum. We first describe the energy equilibrium associated with the charge transfer, as measured from Kelvin probe microscopy measurement. It reveals the NC quantum confinement (blue-shift of the silicon NC conduction band edges as a function of the nanocrystal size, typically up to the eV range), in good quantitative agreement with tight-binding calculations for hydrogen-passivated silicon nanocrystals. We also show that the charge transfer from doped NCs towards a two-dimensional layer experimentally follows a simple phenomenological law, corresponding to formation of an interface dipole linearly increasing with the NC diameter. These feature lead to analytically predictable junction properties down to quantum size regimes: NC depletion width independent of the NC size and varying as ND-1/3, and depleted charge linearly increasing with the NC diameter and varying as ND1/3. This analytical model establishes a "nanocrystal counterpart" of conventional semiconductor planar junctions, valid in regimes of strong electrostatic and quantum confinements.
• Multi-spectral Mueller polarimetric imaging detecting residual cancer and cancer regression after neoadjuvant treatment for colorectal carcinomas
  
  • Pierangelo Angelo
  • Manhas Sandeep
  • Benali Abdelali
  • Fallet Clément
  • Totobenazara J.-L.
  • Antonelli Maria Rosaria
  • Novikova Tatiana
  • Gayet Brice
  • de Martino Antonello
  • Validire Pierre
  Journal of Biomedical Optics, Society of Photo-optical Instrumentation Engineers, 2013, 18 (4), pp.046014.
• Charge Distribution and Contact Resistance Model for Coplanar Organic Field-Effect Transistors
  
  • Kim Chang Hyun
  • Bonnassieux Yvan
  • Horowitz Gilles
  IEEE Transactions on Electron Devices, Institute of Electrical and Electronics Engineers, 2013, 60 (1), pp.280. We propose a theoretical description of the charge distribution and the contact resistance in coplanar organic field-effect transistors (OFETs). Based on the concept that the current in organic semiconductors is only carried by injected carriers from the electrodes, an analytical formulation for the charge distribution inside the organic layer was derived. We found that the contact resistance in coplanar OFETs arises from a sharp low-carrier-density zone at the source/channel edge because the gate-induced channel carrier density is orders of magnitude higher than the source carrier density. This image is totally different from the contact resistance in staggered OFETs, in which the contact resistance mainly originates from the resistance through the semiconductor bulk. The contact resistance was calculated through charge-distribution functions, and the model could explain the effect of the gate voltage and injection barrier on the contact resistance. Experimental data on pentacene OFETs were analyzed using the transmission-line method. We finally noticed that the gate-voltage-dependent mobility is a critical factor for proper understanding of the contact resistance in real devices. (10.1109/ted.2012.2226887)
  DOI : 10.1109/ted.2012.2226887
• Doped semiconductor nanocrystal junctions
  
  • Borowik Lukasz
  • Nguyen-Tran Thuat
  • Roca I Cabarrocas Pere
  • Melin Thierry
  Journal of Applied Physics, American Institute of Physics, 2013, 114, pp.204305, 5 pages. Semiconductor junctions are the basis of electronic and photovoltaic devices. Here, we investigate junctions formed from highly doped (ND 1020 1021cm 3) silicon nanocrystals (NCs) in the 2-50 nm size range, using Kelvin probe force microscopy experiments with single charge sensitivity. We show that the charge transfer from doped NCs towards a two-dimensional layer experimentally follows a simple phenomenological law, corresponding to formation of an interface dipole linearly increasing with the NC diameter. This feature leads to analytically predictable junction properties down to quantum size regimes: NC depletion width independent of the NC size and varying as N 1=3 D , and depleted charge linearly increasing with the NC diameter and varying as N1=3 D . We thus establish a "nanocrystal counterpart" of conventional semiconductor planar junctions, here however valid in regimes of strong electrostatic and quantum confinements. (10.1063/1.4834516)
  DOI : 10.1063/1.4834516
• Sensitization of ZnO nanowire arrays with CuInS < sub>2 < /sub> for extremely thin absorber solar cells < sup>a) < /sup&gt
  
  • Sanchez Sylvia
  • Aldakov Dmitry
  • Rouchon Denis
  • Rapenne Laëtitia
  • Delamoreanu Alexandru
  • Lévy-Clément Claude
  • Ivanova Valentina
  Journal of Renewable and Sustainable Energy, AIP Publishing, 2013, 5 (1), pp.011207. no abstract (10.1063/1.4791780)
  DOI : 10.1063/1.4791780
• Multi-resonant absorption in ultra-thin silicon solar cells with metallic nanowires
  
  • Massiot I.
  • Colin Clément
  • Sauvan Christophe
  • Lalanne Philippe
  • Roca I Cabarrocas Pere
  • Pelouard Jean-Luc
  • Collin Stéphane
  Optics Express, Optical Society of America - OSA Publishing, 2013, 21 (S3), pp.A372-A381. We propose a design to confine light absorption in flat and ultra-thin amorphous silicon solar cells with a one-dimensional silver grating embedded in the front window of the cell.We show numerically that multi-resonant light trapping is achieved in both TE and TM polarizations. Each resonance is analyzed in detail and modeled by Fabry-Perot resonances or guided modes via grating coupling. This approach is generalized to a complete amorphous silicon solar cell, with the additional degrees of freedom provided by the buffer layers. These results could guide the design of resonant structures for optimized ultra-thin solar cells. (10.1364/OE.21.00A372)
  DOI : 10.1364/OE.21.00A372
• Polarimetric imaging of uterine cervix: a case study
  
  • Pierangelo Angelo
  • Nazac André
  • Benali Abdelali
  • Validire Pierre
  • Cohen Henri
  • Novikova Tatiana
  • Haj Ibrahim Bicher
  • Manhas Sandeep
  • Fallet Clément
  • Antonelli Maria Rosaria
  • de Martino Antonello
  Optics Express, Optical Society of America - OSA Publishing, 2013, 21 (12), pp.14120-14130. We present a preliminary investigation of macroscopic polarimetric imaging of uterine cervix. Orthogonal state contrast (OSC) images of healthy and anomalous cervices have been taken in vivo at 550 nm. Four ex vivo cervix samples have been studied in full Muller polarimetry, at 550 nm and 700 nm, and characterized in detail by standard pathology. One sample was totally healthy, another one carried CIN lesions at very early stage (CIN1) in its visible exocervical region, while for the other two samples more advanced (CIN3) lesions were present, together with visible glandular epithelium (ectropion). Significant birefringence has been observed in the healthy regions of all six samples, both in vivo and ex vivo. Standard treatments of the Mueller images of the ex vivo samples allowed to quantify both retardation and depolarization. Retardation reached 60 in healthy regions, and disappeared in the anomalous regions of the other three ex vivo samples. The depolarization power was largest in healthy regions, and lower in CINs and ectropion. Possible origins of the observed effects are briefly discussed (10.1364/OE.21.014120)
  DOI : 10.1364/OE.21.014120
• High efficient solar cells based on DPTMM (2nd Prix du poster)
  
  • Choi Jin-Woo
  • Geffroy Bernard
  • Tondelier Denis
  • Leliège Antoine
  • Kirchner Eva
  • Blanchard Philippe
  • Roncali Jean
  • Bonnassieux Yvan
  , 2013.
• Structural transitions at the nanoscale: the example of palladium phosphides synthesized from white phosphorus
  
  • Carenco S.
  • Hu Y.
  • Florea I.
  • Ersen O.
  • Boissière C.
  • Sanchez C.
  • Mezailles N.
  Dalton Transactions, Royal Society of Chemistry, 2013, 42 (35), pp.12667-12674. Stoichiometric reactions of Pd(0) nanoparticles with various amounts of white phosphorus (P-4) are an efficient route to convert them into the corresponding Pd phosphides PdxPy. Formation of crystallized palladium phosphide nanoparticles is a two-step process, which allows exploring in detail the phase transitions of the PdxPy system, from amorphous Pd-P nanoparticles (formed in a first step at moderate temperature) to crystallization (at higher temperature). The second temperature was found to be strongly dependent on the Pd/P ratio: PdP2, Pd5P2 and Pd3P stoichiometries form the amorphous phases, but only PdP2 and Pd5P2 could be further crystallized from them. Although it exists as a bulk crystalline material, Pd3P could only be crystallized by starting from the more Pd-rich Pd6P composition. Phase-to-phase transformations from P-poor phosphides (Pd3P and Pd5P2) to the P-rich PdP2 were also demonstrated, and a first Pd-P phase diagram at the nanoscale was tentatively produced. (10.1039/c3dt50686j)
  DOI : 10.1039/c3dt50686j