Publications

2014

• Engineering of CVD graphene optoelectronic properties Application as transparent electrode in solar cells
  
  • Arezki Hakim
  • Boutchich Mohamed
  • Alamarguy David
  • Gunes Fethullah
  • Madouri Ali
  • Alvarez José
  • Roca I Cabarrocas Pere Roca I Cabarrocas
  • Kleider Jean-Paul
  • Fei Y.
  • Hee Lee Y.
  , 2014.
• Etching of a-Si:H thin films by hydrogen plasma: A view from in situ spectroscopic ellipsometry
  
  • Hadjadj Aomar
  • Larbi Fadila
  • Gilliot Mickaël
  • Roca I Cabarrocas Pere
  The Journal of Chemical Physics, American Institute of Physics, 2014, 141 (8). (10.1063/1.4893558)
  DOI : 10.1063/1.4893558
• Impedance spectroscopy on copper phthalocyanine diodes with surface-induced molecular orientation
  
  • Kim Chang-Hyun
  • Hlaing Htay
  • Yang Shyuan
  • Bonnassieux Yvan
  • Horowitz Gilles
  • Kymissis Ioannis
  Organic Electronics, Elsevier, 2014, 15 (8), pp.1724-1730. Molecular orientation and packing motif governs charge-transport property of organic semiconductor films, especially for planar small molecules. We analyze the surface-induced orientation of copper phthalocyannine (CuPc) molecules deposited on graphene or poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) covered indium-tin-oxide (PEDOT:PSS/ITO). The CuPc films deposited on graphene are templated with preferential face-on stacking, whereas the molecules on PEDOT:PSS/ITO crystallize with edge-on ordering. Static current-voltage measurement and small-signal impedance spectroscopy are combined to elucidate the structural impact on the electrical response when those films are part of a rectifying diode. The graphene-templated diode shows enhanced out-of-plane hole conduction as compared to the diode with a PEDOT:PSS/ITO contact. Equivalent circuits describing charge injection and transport properties are proposed. (10.1016/j.orgel.2014.04.039)
  DOI : 10.1016/j.orgel.2014.04.039
• Understanding and validation of the polarimetric scattering of a forest for bistatic P-band SAR measurements
  
  • Everaere Etienne
  • Colin Koeniguer Elise
  • Thirion-Lefevre Laetitia
  • de Martino Antonello
  , 2014, pp.4556-4559. The objective of this paper is to propose an alternative measurement device at optical scale to help understanding of bistatic polarimetric SAR images of forests. The device is employed to measure nanoscale trunk forests with a 106 scale factor. Considering the scale invariant rule in electromagnetic scattering this device would enable to predict the Mueller matrix of a whole tree forest for P band radar measurements. The device presents the advantages to be low cost and to get a complete set of bistatic configurations at once. Moreover, the measurements are very fast and would potentially be done on infinitely diverse and well controlled forest structures. Multiplicative decompositions of the Mueller matrix are presented. We underline the trunk density influence for an entire scope of bistatic configuration. (10.1109/IGARSS.2014.6947506)
  DOI : 10.1109/IGARSS.2014.6947506
• Wireless flexible strain sensor based on Carbon Nanotube piezoresistive networks for embedded measurement of strain in concrete
  
  • Michelis Fulvio
  • Lebental Bérengère
  • Cojocaru Costel-Sorin
  • Sorin Jean Luc
  • Bonnassieux Yvan
  , 2014, pp.2p. In the field of Structural Health Monitoring, there is growing interest in continuous volume measurements of material properties using embedded sensors organized in wireless sensor networks (1,2,3). In this work we propose a novel, highly reproducible piezoresistive sensor based on Carbon Nanotube (CNT) networks deposited on polymer to be used for embedded strain monitoring and crack detection in concrete. We highlight the originality of the fabrication process and describe the modalities for signal conditioning and for integration into a RFID-based wireless sensor network. We have achieved the first reported strain gauge fabricated by direct inkjet printing of CNTs on polymeric substrates, namely Ethylene tetrafluoroethylene (ETFE). The strain gauge we propose is of interest for its flexibility and sensitivity (Gauge Factor) which is higher than that of metallic sensors. For these reasons we believe that the proposed strain gauge is a promising alternative to the rigid metallic strain gauges currently on the market. The method is based on the dispersion of CNTs in a solution of 1,2-dichlorobenzene, with sodium dodecyl benzene sulphonate added as surfactant to enhance the solution’s wettability on the polymer. The solution is used as ink to print resistive layers of randomly oriented CNTs on polymer. We optimized the printing and the rinsing process for maximum control of the resistivity and uniformity of the CNT layers. The sensors show a Gauge Factor (GF) of 2.54 which is superior to commercial metallic strain gauges by 25%. Our technology is characterized by its high reproducibility, with only a 6.8% variation of GF values for different sensors fabricated on ETFE. Tests on multiple loading cycles prove the repeatability of the measurements over several loading cycles. Our results suggest that such devices could be used in real life applications. With this goal in mind, we compare several electronic circuits for signal conditioning (from Wheatstone bridge with amplification chain to Sigma-Delta conditioner) in order to select the more appropriate for embedded sensing in concrete. The application dictates two constraints on the electronics: low power consumption and small dimension. We suggest that a configuration based on RFID (Radio Frequency Identification) is the optimum solution given the imposed constraints (4,5). We propose an architecture that can be exploited in conditioning elements sensitive to other parameters of interested for SHM as humidity and pH sensors (6). Although the sensor has its own intrinsic merits, our project presents a complete system (sensor with conditioning electronics) which is innovative, original and intended for a practical application of great importance to modern societies.
• Interface effects on the moisture barrier properties of SiN x /PMMA/SiN x hybrid structure
  
  • Majee Subimal
  • Geffroy Bernard
  • Bonnassieux Yvan
  • Bourée Jean-Eric
  Surface and Coatings Technology, Elsevier, 2014, 254, pp.429-432. Easily degradable organic photovoltaic (OPV) devices based on flexible polymer substrates require barrier films exhibiting extremely low permeation rates for water vapor. We report the barrier properties of hard/ soft alternating layer structures where a soft PMMA layer is sandwiched between two hard SiN x layers. The interfaces between the hard/soft layers hinder the propagation of pinholes from one single-layer to the other and thus have an effect on the overall barrier properties of the whole system. We focus our attention on the effect of increasing number of interfaces on the final barrier properties. The encapsulation barrier properties of these layers are assessed using the electrical calcium test. A minimum water vapor transmission rate (WVTR) of ~ 2 × 10 −4 g/m 2 ·day is reported for 7 hard/soft interfaces, which has also high potential for flexible barrier applications. (10.1016/j.surfcoat.2014.06.059)
  DOI : 10.1016/j.surfcoat.2014.06.059
• anglais
  
  • Dornstetter Jean-Christophe
  • Wang Junkang
  • Bruneau Bastien
  • Johnson Erik V.
  • Roca I Cabarrocas Pere
  Canadian Journal of Physics, NRC Research Press, 2014, 92 (7/8). (10.1139/cjp-2013-0606)
  DOI : 10.1139/cjp-2013-0606
• Structural properties of relaxed thin film germanium layers grown by low temperature RF-PECVD epitaxy on Si and Ge (100) substrates
  
  • Cariou Romain
  • Ruggeri Rosa
  • Tan Xi
  • Mannino Giovanni
  • Nassar Joaquim
  • Roca I Cabarrocas Pere
  AIP Advances, American Institute of Physics- AIP Publishing LLC, 2014, pp.077103. We report on unusual low temperature (175 °C) heteroepitaxial growth of germanium thin films using a standard radio-frequency plasma process. Spectroscopic ellipsometry and transmission electron microscopy (TEM) reveal a perfect crystalline quality of epitaxial germanium layers on (100) c-Ge wafers. In addition direct germanium crystal growth is achieved on (100) c-Si, despite 4.2% lattice mismatch. Defects rising from Ge/Si interface are mostly located within the first tens of nanometers, and threading dislocation density (TDD) values as low as 106 cm−2 are obtained. Misfit stress is released fast: residual strain of −0.4% is calculated from Moiré pattern analysis. Moreover we demonstrate a striking feature of low temperature plasma epitaxy, namely the fact that crystalline quality improves with thickness without epitaxy breakdown, as shown by TEM and depth profiling of surface TDD. (10.1063/1.4886774)
  DOI : 10.1063/1.4886774
• Hybrid photocathode coupling organic solar cells and MoS3 catalyst ofr solar hydrogen production
  
  • Geffroy Bernard
  , 2014.
• Wireless flexible strain sensor based on Carbon Nanotube piezoresistive networks for embedded measurement of strain in concrete
  
  • Michelis Fulvio
  • Lebental Bérengère
  • Cojocaru Costel-Sorin
  • Sorin Jean Luc
  • Bonnassieux Yvan
  , 2014, pp.2p. In the field of Structural Health Monitoring, there is growing interest in continuous volume measurements of material properties using embedded sensors organized in wireless sensor networks (1,2,3). In this work we propose a novel, highly reproducible piezoresistive sensor based on Carbon Nanotube (CNT) networks deposited on polymer to be used for embedded strain monitoring and crack detection in concrete. We highlight the originality of the fabrication process and describe the modalities for signal conditioning and for integration into a RFID-based wireless sensor network. We have achieved the first reported strain gauge fabricated by direct inkjet printing of CNTs on polymeric substrates, namely Ethylene tetrafluoroethylene (ETFE). The strain gauge we propose is of interest for its flexibility and sensitivity (Gauge Factor) which is higher than that of metallic sensors. For these reasons we believe that the proposed strain gauge is a promising alternative to the rigid metallic strain gauges currently on the market. The method is based on the dispersion of CNTs in a solution of 1,2-dichlorobenzene, with sodium dodecyl benzene sulphonate added as surfactant to enhance the solution’s wettability on the polymer. The solution is used as ink to print resistive layers of randomly oriented CNTs on polymer. We optimized the printing and the rinsing process for maximum control of the resistivity and uniformity of the CNT layers. The sensors show a Gauge Factor (GF) of 2.54 which is superior to commercial metallic strain gauges by 25%. Our technology is characterized by its high reproducibility, with only a 6.8% variation of GF values for different sensors fabricated on ETFE. Tests on multiple loading cycles prove the repeatability of the measurements over several loading cycles. Our results suggest that such devices could be used in real life applications. With this goal in mind, we compare several electronic circuits for signal conditioning (from Wheatstone bridge with amplification chain to Sigma-Delta conditioner) in order to select the more appropriate for embedded sensing in concrete. The application dictates two constraints on the electronics: low power consumption and small dimension. We suggest that a configuration based on RFID (Radio Frequency Identification) is the optimum solution given the imposed constraints (4,5). We propose an architecture that can be exploited in conditioning elements sensitive to other parameters of interested for SHM as humidity and pH sensors (6). Although the sensor has its own intrinsic merits, our project presents a complete system (sensor with conditioning electronics) which is innovative, original and intended for a practical application of great importance to modern societies.
• Multi-mode humidity sensitivity of carbon nanotubes field-effect transistors
  
  • Lebental Bérengère
  • Woo Heechul
  • Norman Evgeny
  • Bouanis Fatima Zahra
  • Gohier Aurélien
  • Cojocaru Costel-Sorin
  , 2014, pp.2p. Single-walled carbon nanotube-based field effect transistors have demonstrated highly promising gas sensing properties, especially a particularly strong sensitivity to humidity. The sensitivity to humidity impairs the use of the transistors in logic circuits, while the devices are usually very unstable as humidity sensors. The humidity dependence of electrical characteristics is generally attributed to charge trapping and water adsorption either on the oxide layer or on the nanotubes surface, but a detailed understanding of the mechanisms is prevented by the diversity of behaviors reported throughout the literature as well as by the response variability observed even with batch-fabricated samples [1]. We propose here a novel analysis of the different modes of humidity sensitivity in CNTFET based on a systematic, extensive multiparameter study of the electrical response of a series of CNTFET devices. We consider transistors whose channel consist in a network of mostly semiconducting, in-place CVD-grown SWNTs directly connecting source and drain electrodes [2], and we monitor systematically the characteristics of the transfer curves with respect to humidity in a metrological approach (Imax, Imin, threshold voltage, hysteresis voltage, subthreshold slope...). The significant variability of responses is interpreted using a compact-model-based approach [3]: we introduce a humidity-modulated voltage difference between effective gate voltage along the nanotube and imposed gate voltage. Using this approach, we rigorously interpret the variation of all the parameters while confirming the existence of two regimes, one at low humidity involving water molecules adsorption around charge trap, the other at high humidity involving a charging effect in the full layer of water molecules adsorbed on the oxide surface.
• The Sense-City equipment project: 9M¤ for prototyping and validation of nanosensors for sustainable cities
  
  • Lebental Bérengère
  • Derkx François
  • Bourquin Frédéric
  • Bourouina Tarik
  • Mercier Bruno
  • Cojocaru Costel-Sorin
  • Roca Pere
  • Ha Thi-Lan
  • Robine Enric
  , 2014, pp.2 p. While today’s galloping urbanization weighs heavily on both People and Environment, the massive instrumentation of urban spaces appears a landmark toward sustainability. Because of their high sensitivity, the wide range of their observables, their energetic self-sufficiency and their low cost, nanosensors appear particularly well suited to urban metrology. A 8 years, 9 M¤ equipment project funded by the French ‘Programme d’Investissement d’Avenir’ starting in 2012, Sense-City project offers high-quality facilities for prototyping and performance assessment of urban nanosensors. Sense-City is built around four programs, environmental monitoring, structural health monitoring, energy performances monitoring and people exposure monitoring. We present the activities of the consortium partners along these lines, the complementarity of our skills enabling the design of decision-support tools based on innovative sensors, precise modeling as well as data management and visualization. We also discuss the shortcomings of evaluating the performances of sensors only in lab conditions or directly in real, urban conditions. As a solution, Sense-City will provide an environment of intermediate complexity for the testing of environmental sensors, a realistic urban test space in climatic conditions, both far more complex than clean rooms and far more controllable than actual cities.
• Demonstration of Mueller polarimetry through an optical fiber for endoscopic applications
  
  • Vizet Jérémy
  • Manhas Sandeep
  • Deby Stanislas
  • Vanel Jean-Charles
  • de Martino Antonello
  • Pagnoux Dominique
  , 2014, pp.paper JW2A.31.
• Incorporation and redistribution of impurities into silicon nanowires during metal-particle-assisted growth
  
  • Chen Wanghua
  • Yu Linwei
  • Misra Soumyadeep
  • Fan Zheng
  • Pareige Philippe
  • Patriarche Gilles
  • Bouchoule Sophie
  • Cabarrocas Pere Roca I
  Nature Communications, Nature Publishing Group, 2014, 5. (10.1038/ncomms5134)
  DOI : 10.1038/ncomms5134
• Understanding the amorphous-to-microcrystalline silicon transition in SiF4/H2/Ar gas mixtures
  
  • Dornstetter Jean-Christophe
  • Bruneau Bastien
  • Bulkin Pavel
  • Johnson Erik V.
  • Roca I Cabarrocas Pere
  The Journal of Chemical Physics, American Institute of Physics, 2014, 140 (23). (10.1063/1.4883503)
  DOI : 10.1063/1.4883503
• Evolution in morphological, optical, and electronic properties of ZnO:Al thin films undergoing a laser annealing and etching process
  
  • Charpentier C.
  • Boukhicha R.
  • Prod׳homme P.
  • Emeraud T.
  • Lerat J.-F.
  • Cabarrocas P. Roca I
  • Johnson E.V.
  Solar Energy Materials and Solar Cells, Elsevier, 2014, 125. (10.1016/j.solmat.2014.02.027)
  DOI : 10.1016/j.solmat.2014.02.027
• Nanosecond-laser-induced graphitization and amorphization of thin nano-crystalline graphite films
  
  • Loisiel Loïc
  • Lebental Bérengère
  • Samani Majid Kabiri
  • Tan Chong Wei
  • Cojocaru Costel Sorin
  • Baillargeat Dominique
  • Tay Beng Kang
  , 2014, pp.1p. To develop optically-controlled resistive memories, we study the laser-induced graphitization and amorphization of vertically oriented nano-crystalline graphite (vnC-G) thin films deposited with the filtered cathodic vacuum arc method. vnc-G films consist in graphitic planes perpendicular to the substrate within a matrix of amorphous carbon [1]. Controlled graphitization and amorphization of carbon materials is a long-standing issue with unclear mechanisms [2-5]. Here, we report on graphitization and amorphization of vnc-G controlled by single 532 nm-5 ns laser pulses of various intensities. We demonstrate partial reversibility between graphitization and amorphization, opening the way toward device applications. Depending on pulse energy, samples also display an intricate typology of degradations, from periodic ripples, cracks, upheavals and spheroids to traces of explosions. Supported by a finite-element thermo-mechanical model, we discuss the impact of the orientation of the graphitic planes.
• Imagerie optique non linéaire ou de polarisation de la matrice exrtracellulaire
  
  • Ducourthial Guillaume
  • Vizet Jérémy
  • Manhas Sandeep
  • Leclerc Pierre
  • Mansuryan Tigran
  • Desroches Jérôme
  • Brevier Julien
  • de Martino Antonello
  • Pagnoux Dominique
  • Louradour Frédéric
  , 2014.
• Vers une caracterisation polarimétrique de Mueller endocopique pour l'aide au diagnostic médical
  
  • Vizet Jérémy
  • Manhas Sandeep
  • Deby Stanislas
  • Vanel Jean-Charles
  • de Martino Antonello
  • Pagnoux Dominique
  , 2014, pp.page 53.
• Assembling organic solar cells and catalysts for water reduction: hybrid photocathode for solar hydrogen production
  
  • Bourgeteau Tiphaine
  • Tondelier Denis
  • Cabaret Théo
  • Derycke Vincent
  • Jousselme Bruno
  • Geffroy Bernard
  , 2014.
• An overview of polarimetric sensing techniques and technology with applications to different research fields
  
  • Snik Frans
  • Craven-Jones Julia
  • Escuti Michael
  • Fineschi Silvano
  • Harrington David
  • de Martino Antonello
  • Mawet Dimitri
  • Riedi Jerome
  • Tyo J. Scott
  , 2014. (10.1117/12.2053245)
  DOI : 10.1117/12.2053245
• Influence of low energy argon plasma treatment on the moisture barrier performance of hot wire-CVD grown SiN x multilayers Influence of low energy argon plasma treatment on the moisture barrier performance of hot wire-CVD grown SiN x multilayers
  
  • Majee Subimal
  • Fátima Cerqueira Maria
  • Tondelier Denis
  • Geffroy Bernard
  • Bonnassieux Yvan
  • Alpuim Pedro
  • Bouree Jean Eric
  Jpn. J. Appl. Phys, 2014, 53, pp.05FM05. The reliability and stability are key issues for the commercial utilization of organic photovoltaic devices based on flexible polymer substrates. To increase the shelf-lifetime of these devices, transparent moisture barriers of silicon nitride (SiN x) films are deposited at low temperature by hot wire CVD (HW-CVD) process. Instead of the conventional route based on organic/inorganic hybrid structures, this work defines a new route consisting in depositing multilayer stacks of SiN x thin films, each single layer being treated by argon plasma. The plasma treatment allows creating smoother surface and surface atom rearrangement. We define a critical thickness of the single layer film and focus our attention on the effect of increasing the number of SiN x single-layers on the barrier properties. A water vapor transmission rate (WVTR) of 2 ' 10 %4 g/(m 2 &day) is reported for SiN x multilayer stack and a physical interpretation of the plasma treatment effect is given. (10.7567/JJAP.53.05FM05)
  DOI : 10.7567/JJAP.53.05FM05
• Polarimétrie de Mueller déportée par fibre optique
  
  • Manhas Sandeep
  • Vizet Jérémy
  • Deby Stanislas
  • Vanel Jean-Charles
  • de Martino Antonello
  • Pagnoux Dominique
  , 2014.
• Understanding Light Harvesting in Radial Junction Amorphous Silicon Thin Film Solar Cells
  
  • Yu Linwei
  • Misra Soumyadeep
  • Wang Junzhuan
  • Qian Shengyi
  • Foldyna Martin
  • Xu Jun
  • Shi Yi
  • Johnson Erik
  • Cabarrocas Pere Roca I
  Scientific Reports, Nature Publishing Group, 2014, 4, pp.4357. (10.1038/srep04357)
  DOI : 10.1038/srep04357
• 9,9'-Spirobifluorene and 4-phenyl-9,9'- spirobifluorene: pure hydrocarbon small molecules as hosts for efficient green and blue PhOLEDs
  
  • Thiery Sebastien
  • Tondelier Denis
  • Declairieux Ce
  • Gijun Seo
  • Geffroy Bernard
  • Jeannin Olivier
  • Rault-Berthelot Joëlle
  • Métivier Rémi
  • Poriel Cyril
  Journal of Materials Chemistry C, Royal Society of Chemistry, 2014, 2 (21), pp.4156-4166. We report herein a new pure hydrocarbon material, 4-phenyl-9,9′-spirobifluorene (4-Ph-SBF), with a high triplet energy level (ET: 2.77 eV) as a host for blue phosphorescent organic light-emitting diodes (PhOLEDs). Structural, thermal, electrochemical and photophysical properties have been investigated in detail and compared to its constituting building block 9,9′-spirobifluorene (SBF) in order to precisely study the influence of the incorporation of a phenyl unit in C4. A surprising out of plane deformation of the fluorene ring and a highly twisted structure have been notably found for 4-Ph-SBF due to the substitution in C4. As both 4-Ph-SBF and SBF possess a high triplet energy level (2.77/2.87 eV resp.), they have been successfully used as host materials for green and blue PhOLEDs. The performance of blue PhOLEDs, ca. 20 cd A−1, appears to be among the highest reported for pure hydrocarbon derivatives. (10.1039/c4tc00171k)
  DOI : 10.1039/c4tc00171k