Publications

2012

• A new vertical nanoporous functional structure process fabrication to control one dimensional nanostructure growth
  
  • Lefeuvre Emmanuel
  • Kim Ki Hwan
  • Châtelet Marc
  • Cojocaru Costel Sorin
  MRS Online Proceedings Library, Cambridge University Press, 2012, 1411 (1), pp.1. A novel vertical nanoporous structure is reported as a starting point for the fabrication of a fully-surround gate field effect transistor (FET) based on well-ordered nanostructures array. The proposed porous stacking is perfectly suited both for the collective organization of high density (up to 1011.cm-2) arrays of nanostructures like nanowires (NWs) or nanotubes (NTs), as with calibrated diameters (during growth), as well as for easing the Source, Gate, and Drain electrodes connections for individual or groups of nanostructures. Moreover the unique fully-surround gate architecture enables a quasi-ideal coupling between the gate and the channel, theoretically leading to improved devices performance and reduced global power consumption. In this paper we describe the main steps for this versatile and lithography-free technique to fabricate a multi-layer porous template down to the nanometer scale, as well as the first nanostructures (carbon NTs) growth attempts inside such functional template. We highlight the fact that the proposed porous structure may acts as a passive template for the one-dimensional nanomaterials growth as well as an active element in the future device. The proposed approach is in line with bottom-up fabrication approach to provide smaller devices, and is fully-compatible with classical processes used in the silicon industry. (10.1557/opl.2012.756)
  DOI : 10.1557/opl.2012.756
• Porous Alumina Template based Versatile and Controllable Direct Synthesis of Silicon nanowires
  
  • Kim Ki Hwan
  • Lefeveure Emmanuel
  • Châtelet Marc
  • Cojocaru Costel Sorin
  MRS Online Proceedings Library, Cambridge University Press, 2012, 1439 (1), pp.x. Highly densely packed, self-organized silicon nanowires with very narrow diameter distribution were synthesized within porous anodic alumina templates with electrodeposited catalytic metal nanoparticles. For successful catalytic metal nanoparticle deposition, electrochemical-, and chemical barrier layer thinning process was investigated following anodization process. Controlled pulsed electrodeposition process was carried out for a volume calibration of desired catalytic metal nanoparticle deposition inside nanopore arrays using different metal-ion containing electrolyte. Not only single metal nanoparticles, but also multi metal nanoparticles layers were filled inside PAA to enhance metal filling aspect, and to control the volume of nanoparticles more precisely. Using multilayered metal nanoparticles resulted on different SiNW's growth behavior depending on the types of underlying metal nanoparticles. SiNWs were successfully synthesized using hot-filament assisted chemical vapor deposition system. Although silicon precursor gas can generally be dissociated at relatively low temperatures, the use of a hot filament activation help decreasing process temperature, and also, highly activated atomic hydrogen generation via the tungsten hot filament placed at gas inlet helps preventing parasitic amorphous silicon deposition on either the alumina membrane surface or the pore wall which hinders appropriate growth of SiNWs in PAA by nanopores clogging. Such densely packed, self-organized SiNWs are of high interest in many application fields like nanoelectronics, optoelectronics, and energy storage/conversion devices etc. (10.1557/opl.2012.940)
  DOI : 10.1557/opl.2012.940
• MEMS electrodynamic loudspeakers for mobile phones
  
  • Lemarquand G.
  • Ravaud R.
  • Shahosseini I.
  • Lemarquand Valérie
  • Moulin J.
  • Lefeuvre E.
  Applied Acoustics, Elsevier, 2012, 73 (4), pp.379-385. This paper presents a MEMS structure of electrodynamic loudspeakers dedicated to mobile phone applications. The major goals are to obtain a high electroacoustic conversion efficiency and a high fidelity acoustic quality. The originalities lie in a rigid silicon membrane and in its suspension by a set of silicon beams. The moving coil is a planar copper microcoil electroplated on the silicon membrane whose microstructure was optimized for providing both rigidity and lightness of the mobile part. This paper presents different magnetic structures of the motor for this MEMS loudspeaker. These structures are ironless, only made out of permanent magnets which are bonded on the substrate. They are studied and optimized thanks to analytical formulations of the magnetic field created by the permanent magnets. Results are presented for a deep RIE etched 7.5 mm radius silicon membrane structured with 40 stiffening ribs and on a 30 μm thick microcoil with 35 turns. (10.1016/j.apacoust.2011.10.013)
  DOI : 10.1016/j.apacoust.2011.10.013
• Ex vivo photometric and polarimetric multilayer characterization of human healthy colon by multispectral Mueller imaging
  
  • Pierangelo Angelo
  • Manhas Sandeep
  • Benali Abdelali
  • Fallet Clément
  • Antonelli Maria Rosaria
  • Novikova Tatiana
  • Validire Pierre
  • Gayet Brice
  • de Martino Antonello
  Journal of Biomedical Optics, Society of Photo-optical Instrumentation Engineers, 2012, 17, pp.066009.
• Spray-gun deposition of catalyst for large area and versatile synthesis of carbon nanotubes
  
  • Gohier Aurelien
  • Kim Ki Hwan
  • Norman Evgeny
  • Gorintin Louis
  • Bondavalli Paolo
  • Cojocaru Costel Sorin
  Applied Surface Science, Elsevier, 2012, 258, pp.6024-6028. Spray gun deposition technique was investigated for large area deposition of nano-catalysts. In particular, we studied iron chloride salts solutions as catalyst precursor for the synthesis of carbon nanotubes (CNTs). Iron chloride salts are shown to decompose upon thermal annealing into Fe(III) oxide based species that make it suitable for further growth of various carbon nanotube structures. Depending on the spraying process, versatile synthesis of 2-D single-walled carbon nanotube network as well as vertically aligned carbon nanotubes arrays on functional substrates can be achieved. Such simple process for the preparation of CNT-based architecture opens new perspectives in the field of thin-film transistor and nanostructured electrodes. (10.1016/j.apsusc.2012.02.115)
  DOI : 10.1016/j.apsusc.2012.02.115
• Magneto-structural and photophysical investigations on a dinuclear Sm(III) complex featuring 2,2'-bipyrimidine
  
  • Zucchi Gaël
  • Le Goff X. F
  Inorganica Chimica Acta, Elsevier, 2012, 380, pp.354-357. A homobimetallic complex, [{Sm(tta)3(MeOH)}2(μ-bpm)]*1 bpm (tta = 2-thenoyltrifluoroacetonato, bpm = 2,2′-bipyrimidine) has been synthesized and structurally characterized by single-crystal X-ray diffraction. Magnetic measurements (between 5 and 295 K) show that the two metal centers bridged by the bpm connector are magnetically almost isolated. The SmIII emission is observed upon excitation in a wide range of wavelengths going from the UV to the visible (250-500 nm). (10.1016/j.ica.2011.10.043)
  DOI : 10.1016/j.ica.2011.10.043
• Genetic framework of cyclin-dependent kinase function in Arabidopsis
  
  • Nowack M.K.
  • Harashima H.
  • Dissmeyer N.
  • Zhao X.
  • Bouyer D.
  • Weimer A.K.
  • de Winter F.
  • Yang F.
  • Schnittger A.
  Developmental Cell, Elsevier, 2012, 22 (5), pp.1030-40. Cyclin-dependent kinases (CDKs) are at the heart of eukaryotic cell-cycle control. The yeast Cdc2/CDC28 PSTAIRE kinase and its orthologs such as the mammalian Cdk1 have been found to be indispensable for cell-cycle progression in all eukaryotes investigated so far. CDKA;1 is the only PSTAIRE kinase in the flowering plant Arabidopsis and can rescue Cdc2/CDC28 mutants. Here, we show that cdka;1 null mutants are viable but display specific cell-cycle and developmental defects, e.g., in S phase entry and stem cell maintenance. We unravel that the crucial function of CDKA;1 is the control of the plant Retinoblastoma homolog RBR1 and that codepletion of RBR1 and CDKA;1 rescued most defects of cdka;1 mutants. Our work further revealed a basic cell-cycle control system relying on two plant-specific B1-type CDKs, and the triple cdk mutants displayed an early germline arrest. Taken together, our data indicate divergent functional differentiation of Cdc2-type kinases during eukaryote evolution. (10.1016/j.devcel.2012.02.015)
  DOI : 10.1016/j.devcel.2012.02.015
• Characterization of the pentacene thin-film transistors with an epoxy resin-based polymeric gate insulator
  
  • Kim Chang Hyun
  • Tondelier Denis
  • Geffroy Bernard
  • Bonnassieux Yvan
  • Horowitz Gilles
  European Physical Journal: Applied Physics, EDP Sciences, 2012, 57, pp.20201. The organic thin-film transistors (OTFTs) incorporating pentacene/SU-8 interface were fabricated and characterized. SU-8, a reliable epoxy-based photoresist, is tested as a potential highly-stable polymeric gate dielectric for OTFTs. The fabricated devices showed promising electrical performance with on-off ratio up to 10^7 and field-effect mobility up to 0.56 cm^2/V s. Several device characteristics are further analyzed. There existed a leakage current path due to the uncontrolled pentacene coverage and we revealed that precise alignment of the evaporation mask of pentacene is critical for eliminating this problem. Pentacene grain formation largely depended on the growth condition on the SU-8 surface and small-grain films offered outstanding performance possibly owing to enhanced inter-domain connections. Natural degradation of the OTFTs is also discussed in terms of environmental stability and the pentacene/SU-8 transistor operated with noticeable air stability under ambient conditions. (10.1051/epjap/2011110272)
  DOI : 10.1051/epjap/2011110272
• Composition and local strain mapping in Au-catalyzed axial Si/Ge nanowires
  
  • Vincent L.
  • Boukhicha R.
  • Cherkashin Nikolay
  • Reboh Shay
  • Patriarche G.
  • Renard C.
  • Yam V.
  • Fossard F.
  • Bouchier D.
  Nanotechnology, Institute of Physics, 2012, 23 (39). For most applications, heterostructures in nanowires (NWs) with lattice mismatched materials are required and promise certain advantages thanks to lateral strain relaxation. The formation of Si/Ge axial heterojunctions is a challenging task to obtain straight, defect free and extended NWs. And the control of the interface will determine the future device properties. This paper reports the growth and analysis of NWs consisting of an axial Si/Ge heterostructure grown by a vapor–liquid–solid process. The composition gradient and the strain distribution at the heterointerface were measured by advanced quantitative electron microscopy methods with a resolution at the nanometer scale. The transition from pure Ge to pure Si shows an exponential slope with a transition width of 21 nm for a NW diameter of 31 nm. Although diffuse, the heterointerface makes possible strain engineering along the axis of the NW. The interface is dislocation-free and a tensile out-of-plane strain is noticeable in the Ge section of the NW, indicating a lattice accommodation. Experimental results were compared to finite element calculations. (10.1088/0957-4484/23/39/395701)
  DOI : 10.1088/0957-4484/23/39/395701
• Preparation and Characterization of Thin Conductive Polymer Films on the base of PEDOT:PSS by Ink-Jet Printing
  
  • Perinka Nikola
  • Kim Chang Hyun
  • Kaplanova Marie
  • Bonnassieux Yvan
  , 2013, 44, pp.120-129. Owing to its high application potential, the printed functional layers and devices on flexible substrates attract attention of many scientists, in the last few years. Very promising area is represented by so called printed conductive polymers (polyaniline, polythiophene or polypyrroles, etc.). Currently, the most widespread conductive polymer is so called PEDOT:PSS [poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate)]. A widely used technique for the deposition of this conductive polymer is spin-coating. Since the spin-coating technique is not capable of the fine structure pattering (e.g. electrode systems for organic devices), in some cases, different techniques are strongly required (e.g. ink-jet printing). This work shows the development of the testing structure system to assess and to characterize the fine patterns of PEDOT:PSS. The testing structures were deposited on various substrates; the transparent flexible polymer foils (polyethylenterephtalate and polyethylenenaphtalene) and also on the glass substrate. The influence of the change of printing parameters, substrate and its treatment and are discussed. (10.1016/j.phpro.2013.04.016)
  DOI : 10.1016/j.phpro.2013.04.016
• Influence of the diameter distribution on the rate capability of silicon nanowires for lithium-ion batteries
  
  • Gohier Aurelien
  • Laik Barbara
  • Pereira-Ramos Jean Pierre
  • Sorin Costel
  • Tran-Van Pierre
  Journal of Power Sources, Elsevier, 2012, 203, pp.135 - 139. For the first time, the effect of the nanowires diameter in terms of size and distribution on electrochemical properties of SiNWs grown by VLS was investigated. The diameter size was tuned by using three different gold catalyst film thicknesses. The crucial influence of this parameter is evidenced through comparison of the charge-discharge behavior and a study of the rate capability for the three samples. The rechargeable capacity as well as the rate capability is shown to be the best when the smallest diameters (<65 nm) are used compared to larger one (<210 nm and <490 nm). High capacity values of 3500 mAh g−1 are obtained for the smallest diameters at C/5 rate but still 2500, 1500 and 500 mAh g− are recovered at C, 2.5 C and 5 C. An excellent cycle life over 50 cycles is achieved at 1.3 C with a capacity of 2500 mAh g−1 . This shows that by tailoring the diameter size and distribution, SiNWs can provide high power density anodes in lithium ion batteries (10.1016/j.jpowsour.2011.12.023)
  DOI : 10.1016/j.jpowsour.2011.12.023
• Electrodynamic MEMS: Application to Mobile Phone Loudspeakers
  
  • Lemarquand Valérie
  • Lemarquand G.
  • Lefeuvre E.
  • Shahosseini I.
  • Ravaud R.
  • Moulin J.
  • Woytasik M.
  • Martinsic E.
  • Pillonet G.
  IEEE Transactions on Magnetics, Institute of Electrical and Electronics Engineers, 2012, 48 (11), pp.3684-3687. This paper presents an electrodynamic MEMS for mobile phone loudspeaker applications. The whole structure of the loudspeaker is a new conception to reach higher performances than in existing devices: a linear behavior to ensure a high acoustic fidelity and a high efficiency to increase the power autonomy. So, the motor is ironless, constituted of permanent magnet only. Several electrodynamic structures are presented and studied with analytical formulations of the magnetic field. The emissive part is a plane silicon surface, very rigid and light, the suspension is achieved by silicon beams, which are not sensitive to mechanical fatigue, the electroplated copper coil is thick and requires a specialist technique to be deposited. The moving part displacements are in a range far larger than in existing MEMS (600 &#956; m). The trends for dimensioning the structure are investigated and prototypes realized and tested, with NdFeB ring magnets. As a result, the 70 dB SPL at 10 cm bandwidth reaches up to 100 kHz, and the behavior is particularly linear. (10.1109/TMAG.2012.2203798)
  DOI : 10.1109/TMAG.2012.2203798
• Electrical-field-induced structural change and charge transfer of lanthanide–salophen complexes assembled on carbon nanotube field effect transistor devices
  
  • Magadur Gurvan
  • Bouanis Fatima
  • Norman Evgeny
  • Guillot Régis
  • Lauret Jean-Sébastien
  • Huc Vincent
  • Cojocaru Costel-Sorin
  • Mallah Talal
  Chemical Communications, Royal Society of Chemistry, 2012, 48 (72), pp.9071. (10.1039/C2CC34134D)
  DOI : 10.1039/C2CC34134D