Publications

2015

• STUDY OF IN-PLANE SILICON NANOWIRES OBTAINED VIA A SOLID-LIQUID-SOLID GROWTH PROCESS AND THEIR SELF- ORGANIZATION FOR ELECTRONIC APPLICATIONS
  
  • Fan Zheng
  , 2015. This is the first Ph.D. thesis on studying the growth of in-plane silicon nanowires (SiNWs) and developing a method for self-organising them for nano-electronics applications. The growth of in-plane SiNWs is based on plasma-enhanced chemical vapour deposition (PECVD) thin film techniques and results from the interaction between a metal droplet and a hydrogenated amorphous silicon (a-Si:H) thin film. This in-plane solid-liquid-solid (IPSLS) growth mode can be considered as a reactive-spreading and moving behaviour of indium droplet on a-Si:H activated by the establishment of a surface energy gradient due to the phase transition from a-Si:H at the advancing NP edge to c-Si at the NP receding edge. In order to integrate IPSLS SiNWs in nano-electronic devices it is of prime importance to organise them in a controllable way. We propose a growth-in-place strategy which enables the SiNWs to grow along pre-patterned guiding steps. Moreover, this technique is applied to form In NPs on the sidewall of buried ITO layers, which facilitates the localization of the step-guided SiNWs. This work sets the basis for the fabrication of SiNW field effect transistors on insulator, which also allows for gate engineering and the obtaining of Fully Depleted Silicon-On-Insulator (FD-SOI).
• Synthesis of carbon nanotubes within porous anodic alumina templates for electronic applications
  
  • Sacco Leandro Nicolas
  , 2015. The present work is devoted to synthesis of carbon nanotubes (CNTs) within porous anodic alumina (PAA) templates for their device application. The template-based approach using PAA structures provides a versatile organized platform that can be easily controlled adjusting the parameters involved in their fabrication. Two different approaches have been adopted for the device fabrication: the conventional vertical-PAA which is obtained by the simply anodization of an aluminum foil and on the other hand lateral-PAA templates have been fabricated requiring lithography steps. The main characteristics of the PAA templates have been deeply studied, in particular the oxide barrier layer at the bottom of the pores. After catalyst deposition hot-filament assisted chemical vapor deposition (HF-CVD) has been implemented for the synthesis of CNTs. The carbon nanotube structure grown within the PAA template has been extensively analyzed by several techniques as SEM, TEM, Raman spectroscopy and electron energy loss spectroscopy. The impact of the PAA geometry on the synthesis of the CNT has been studied analyzing the evolution of the CNTs within the PAA structure at different times. Fabricated devices based on CNTs grown inside lateral-PAA devices have been electrical and optoelectronically characterized. The devices are based on asymmetrical contacted arrays of nanotubes leading to Schoktty photodiodes. A rectifying behavior can be achieved controlling the metal work functions which contact the counter electrode. These devices present a strong photonic response under light illumination, exhibiting potential application in the photovoltaic and photosensing fields . The vertical-PAA devices have been fabricated exploiting the easier fabrication procedure. Humidity measurements have been performed showing promising results for a further gas sensor fabrication in spite of the active element of the sensing device is inside of the vertical-PAA structure. The present work introduces fundamental results of the growth of nanostructures PAA template and above all exhibits two different templates approach fabrication that opens the frontiers of devises based on nanomaterials.
• Performance Analysis of AlxGa1-xAs/epi-Si(Ge) Tandem Solar Cells: A Simulation Study
  
  • Lachaume Raphaël
  • Cariou R.
  • Decobert J.
  • Foldyna M.
  • Hamon G.
  • Cabarrocas P. Roca I
  • Alvarez J.
  • Kleider J.-P.
  Energy Procedia, Elsevier, 2015, 84, pp.41-46. A new strategy for the development of III-V/Si tandem solar cells has recently been proposed consisting in low temperature PECVD epitaxy of silicon or silicon-germanium on gallium-arsenide. This paper thus gives first insights about theoretical but realistic maximum performance of such tandem cells by means of full numerical simulations considering perfect layers and interfaces. The consequences of using a thin epi-Si bottom cell instead of a thick silicon substrate are investigated. In case no light trapping scheme is considered, a minimum epi-layer thickness of 20 μm is mandatory for the tandem to exhibit higher conversion efficiencies than a single GaAs solar cell. The epi-Si can yet be advantageously replaced by an epitaxial silicon-germanium alloy to increase the bottom cell optical absorption and thus decrease the minimum required thickness by a factor of ∼4 (∼5 μm). Finally, simulations show that over 33% efficiency can be obtained for AlxGa1-xAs/epi-Si0.63Ge0.27, which confirms that this is a promising new concept. (10.1016/j.egypro.2015.12.293)
  DOI : 10.1016/j.egypro.2015.12.293
• Cross-sectional investigations on epitaxial silicon solar cells by Kelvin and Conducting Probe Atomic Force Microscopy: Effect of illumination
  
  • Narchi Paul
  • Alvarez José
  • Chrétien Pascal
  • Picardi Gennaro
  • Cariou Romain
  • Foldyna Martin
  • Prod'Homme Patricia
  • Kleider Jean-Paul
  • Cabarrocas Pere Roca I.
  , 2015.
• Banc de caractérisations avancées de modules photovoltaïques de différentes technologies installé à l'observatoire atmosphérique du SIRTA
  
  • Badosa Jordi
  • Nassar Joaquim
  • Migan-Dubois Anne
  • Bourdin Vincent
  • Pavlov Marko
  • Mambrini Thomas
  • Haeffelin Martial
  , 2015.
• Carbon nanotubes sensors for sustainable city: prototyping, integration, reliability and deployment
  
  • Michelis Fulvio
  • Bodelot Laurence
  • Bonnassieux Yvan
  • Lebental Bérengère
  , 2015, pp.13p. While today's galloping urbanization weighs heavily on both People and Environment and while Climate Change increases natural risks worldwide, Internet of Things Technologies stand at the forefront of the efforts toward Greener Cities. Nanosensors fully integrated into wireless sensor node may become instrumental in this field because of their small size, low cost, versatility and low power consumption. Potential applications are environmental monitoring, structural health monitoring, energy performances monitoring or people exposure monitoring. Challenges range from the manufacturing of the sensors with high reproducibility to their full integration into communicating devices, including ensuring device reliability in complex and harsh environmental conditions. Carbon nanotubes (CNT) especially are choice material toward this goal, as they have demonstrated both a very strong sensitivity to a variety of environmental parameters and a strong resilience to chemical and mechanical stress. In the present paper, we present a full proof of concept of the use of carbon nanotubes sensors for urban applications, from the manipulation of the carbon nanotubes to the application of the sensors in real life. Two specific examples are discussed, infrastructure durability monitoring and water quality monitoring. Specific methodologies for reliability analysis of carbon-based nanomaterials are also discussed.
• Realistic simulation of III-V/epi-SiGe tandem solar cells
  
  • Lachaume Raphaël
  • Cariou Romain
  • Decobert Jean
  • Foldyna Martin
  • Hamon Gwenaelle
  • Cabarrocas Pere Roca I.
  • Alvarez J
  • Kleider Jean-Paul
  , 2015.
• Towards realistic simulation of the novel III-V/epi-Si tandem solar cell concept
  
  • Lachaume Raphaël
  • Cariou Romain
  • Decobert Jean
  • Foldyna Martin
  • Hamon Gwenaëlle
  • Roca I Cabarrocas Pere
  • Alvarez J
  • Kleider Jean-Paul
  , 2015. Multijunction solar cells based on III-V compounds have by far the highest conversion efficiency. However, the fabrication cost is very high. An attractive solution to lower the cost while maintaining high efficiencies is to design multijunctions on cheaper substrates such as silicon. Different routes have been taken to cope with lattice mismatch issues between Si and III-Vs: epitaxial growth of GaAs on Si with or without buffer layers or non-epitaxial techniques such as mechanical stacking. A novel approach has been recently presented consisting in direct epitaxial growth of thin Si or SiGe layers on GaAs by low temperature PECVD, where the high crystal quality reported opens a new way for making III-V/Si tandem solar cells. Yet, due to the low deposition rate, the epi-Si layers are still rather thin (~10μm), and though they are assumed to be of high quality, some defects might be still present at the interface or in the bulk. These critical aspects still have to be carefully investigated to evaluate the potential benefits of this novel concept. Here, numerical simulation has definitely a role to play. Therefore, we propose to simulate these novel structures using TCAD tools and to estimate the defect density inside the thin epi-layer based on experimental inputs. Realistic efficiencies achievable by this novel concept will thus be presented and discussed.
• Low Oxidation State and Enhanced Magnetic Properties Induced by Raspberry Shaped Nanostructures of Iron Oxide
  
  • Gerber Olivier
  • Pichon Benoit P.
  • Ulhaq Corinne
  • Greneche Jean-Marc
  • Lefevre Christophe
  • Florea Ileana
  • Ersen Ovidiu
  • Begin Dominique
  • Lemonnier Sébastien
  • Barraud Elodie
  • Begin-Colin Sylvie
  Journal of Physical Chemistry C, American Chemical Society, 2015, 119 (43), pp.24665-24673. Nanostructures with controlled size, morphology, and composition represent a main challenge in materials science because controlling these parameters is fundamental to optimizing the subsequent functional properties. Aggregated nanostructures, combining both individual and collective properties of nanocrystals, offer interesting perspectives to design new magnetic nanomaterials. In that context, original porous raspberry shaped nanostructures consisting of oriented aggregates of ferrite nanocrystals have been synthesized by an one-pot polyol solvothermal method. Synthesis conditions have been optimized to obtain nanostructures featured by similar sizes of about 250 nm and nanocrystal sizes modulated from 5 to 60 nm, leading to porous structures with tunable specific surface area. Structural and magnetic studies of nanostructures as a function of the nanocrystal size evidenced their low oxidation state and enhanced magnetic properties. Indeed, the oriented aggregation of nanocrystals leads to high interface between nanograins reducing significantly their surface oxidation and enhancing their saturation magnetization in comparison to individual nanoparticles of similar sizes. Magnetic moments of each grain are also consequently strongly coupled by dipolar interactions which led to superspin glass effects. (10.1021/acs.jpcc.5b08164)
  DOI : 10.1021/acs.jpcc.5b08164
• Multi-technology photovoltaic module test bench on the SIRTA meteorological and climate observatory
  
  • Migan-Dubois Anne
  • Mambrini Thomas
  • Badosa Jordi
  • Haeffelin Martial
  • Nassar Joaquim
  • Pavlov Marko
  • Bourdin Vincent
  , 2015.
• Photocathodes based on organic semiconductors coupled to a MoS3 catalyst for solar hydrogen production
  
  • Jousselme Bruno
  • Tondelier Denis
  • Geffroy Bernard
  • Artero Vincent
  , 2015.
• Dispositifs OLED réalisés par voie liquide à partir de molécules fluorescentes photopolymérisables
  
  • Geffroy Bernard
  • Derue Lionel
  • Simon Olivier
  • Maindron Tony
  • Ishow Eléna
  , 2015.
• Control of radio frequency capacitively coupled plasma asymmetries using Tailored Voltage Waveforms
  
  • Bruneau Bastien
  , 2015. This thesis describes the study of capacitively coupled plasmas excited with Tailored Voltage Waveforms (TVWs) and their use in silicon thin film fabrication for photovoltaic applications. Tailoring the voltage waveforms applied on an electrode of a plasma reactor is a recent technique, which has been developed after the discovery of the electrical asymmetry effect. Compared to standard sinewaves, TVWs are composed of a fundamental frequency, in the radio frequency domain, and its first harmonics. Any waveform can then be approximated by selecting the first components of its Fourier series. It has been shown for example that the ion energy can be controlled by the amplitude asymmetry of the waveform, the ion flux being kept constant. However, at high pressure, this decoupling weakens. We further explore the reasons behind it, using both simulations and experiments. Based on this knowledge, we make use of the ability of TVWs to vary the ion energy to understand its effect on silicon thin film deposition. We find well-defined energy thresholds above which we observe, through several characterization techniques, a lower nucleation density in the case of microcrystalline silicon growth. This indicates that ions with energy above these thresholds can break the crystalline bonds. We confirm this result by studying low-temperature epitaxial growth on a crystalline silicon wafer. Above the energy threshold, epitaxy breakdown occur, and distinct amorphous columns are observed in cross-section transmission electron microscopy images, which are initiated at locations where the crystal was broken by high energy ions. Because of unexpected different nucleation densities for sawtooth-up and down waveforms, despite the similar ion energies, we further explore the effect of these waveforms on plasma discharges. We find, using simulations in argon, that the asymmetry in the sheaths motion created by these waveforms induces a strong localization of the ionization events close to one electrode, and consequently a strong ion flux asymmetry. This localization is confirmed experimentally with phase-resolved optical emission spectroscopy. Surprisingly, we find that, for a given waveform, this asymmetry can be reversed for different chemistries (namely CF4 plasmas), because of different electron heating mechanisms. This new asymmetry can be fully controlled via the rise-to-fall ratio of the waveform, i.e. its temporal asymmetry, and therefore opens the path for new applications of TVWs.
• Plasma-Texturing Processes and a-Si:H Surface Passivation on c-Si Wafers for Photovoltaic Applications
  
  • Murias D.
  • Moreno M.
  • Reyes-Betanzo C.
  • Torres A.
  • Ambrosio R.
  • Rosales P.
  • Martinez José
  • Vivaldo I.
  • Roca I Cabarrocas P.
  Journal of Solar Energy Engineering, American Society of Mechanical Engineers, 2015, 137 (5). (10.1115/1.4031105)
  DOI : 10.1115/1.4031105
• Investigation of Photovoltaic Properties of Single Core–Shell GaN/InGaN Wires
  
  • Messanvi A.
  • Zhang H.
  • Neplokh V.
  • Julien F. H.
  • Bayle F.
  • Foldyna M.
  • Bougerol C.
  • Gautier E.
  • Babichev A.
  • Durand C.
  • Eymery J.
  • Tchernycheva M.
  ACS Applied Materials & Interfaces, Washington, D.C. : American Chemical Society, 2015, 7 (39), pp.21898–21906. (10.1021/acsami.5b06473)
  DOI : 10.1021/acsami.5b06473
• Piezoresistivity of thin film semiconductors with application to thin film silicon solar cells
  
  • Lange D.
  • Cabarrocas P.Roca I
  • Triantafyllidis N.
  • Daineka D.
  Solar Energy Materials and Solar Cells, Elsevier, 2015. (10.1016/j.solmat.2015.09.014)
  DOI : 10.1016/j.solmat.2015.09.014
• Bi-Sn alloy catalyst for simultaneous morphology and doping control of silicon nanowires in radial junction solar cells
  
  • Yu Zhongwei
  • Lu Jiawen
  • Qian Shengyi
  • Misra Soumyadeep
  • Yu Linwei
  • Xu Jun
  • Xu Ling
  • Wang Junzhuan
  • Shi Yi
  • Chen Kunji
  • Roca I Cabarrocas Pere
  Applied Physics Letters, American Institute of Physics, 2015, 107 (16). (10.1063/1.4933274)
  DOI : 10.1063/1.4933274
• Dispositif et méthode de caractérisation polarimétrique déportée par fibre optique
  
  • de Martino Antonello
  • Pagnoux Dominique
  • Vizet Jérémy
  • Manhas Sandeep
  • Vanel Jean-Charles
  • Deby Stanislas
  , 2015, pp.Brevet international.
• Effect of argon ion energy on the performance of silicon nitride multilayer permeation barriers grown by hot-wire CVD on polymers
  
  • Alpuim P
  • Majee S
  • Cerqueira M.F.
  • Tondelier D
  • Geffroy B
  • Bonnassieux Y
  • Bouree Jean Eric
  Thin Solid Films, Elsevier, 2015, 595, pp.258-265. Permeation barrier Polymer substrate Permeation barriers for organic electronic devices on polymer flexible substrates were realized by combining stacked silicon nitride (SiN x) single layers (50 nm thick) deposited by hot-wire chemical vapor deposition process at low-temperature (~100°°C) with a specific argon plasma treatment between two successive layers. Several plasma parameters (RF power density, pressure, treatment duration) as well as the number of single layers have been explored in order to improve the quality of permeation barriers deposited on polyethylene tere-phthalate. In this work, maximum ion energy was highlighted as the crucial parameter making it possible to minimize water vapor transmission rate (WVTR), as determined by the electrical calcium test method, all the other parameters being kept fixed. Thus fixing the plasma treatment duration at 8 min for a stack of two SiN x single layers, a minimum WVTR of 5 × 10 −4 g/(m 2 day), measured at room temperature, was found for a maximum ion energy of ~30 eV. This minimum WVTR value was reduced to 7 × 10 −5 g/(m 2 day) for a stack of five SiN x single layers. The reduction in the permeability is interpreted as due to the rearrangement of atoms at the interfaces when average transferred ion energy to target atoms exceeds threshold displacement energy. (10.1016/j.tsf.2015.09.048)
  DOI : 10.1016/j.tsf.2015.09.048
• Device and method for remote polarimetric characterisation
  
  • de Martino Antonello
  • Pagnoux Dominique
  • Vizet Jérémy
  • Manhas Sandeep
  • Vanel Jean-Charles
  • Deby Stanislas
  , 2015.
• Investigation of Hybrid Tunnel Junction Architectures for III-V/Si Tandem Solar Cells
  
  • Hamon Gwenaelle
  • Cariou Romain
  • Lachaume Raphaël
  • Decobert Jean
  • Louarn Kevin
  • Chen Wanghua
  • Alvarez J
  • Kleider Jean-Paul
  • Cabarrocas Pere Roca I.
  , 2015, pp.75-79. We fabricated n-Si/p-GaAs and p-Si/n-GaAs junctions, by combining low temperature (under 200°C) RF-PECVD for Si and MOVPE for GaAs. In particular, we focused on low-resistance Si/GaAs tunnel junctions (< 1 mΩ.cm 2) suitable for the interconnection of two subcells in tandem III-V/Si solar cells. We first demonstrate the growth of highly doped epitaxial silicon films on GaAs despite the 4% lattice-match between these two materials. Spectroscopic ellipsometry measurements were used to confirm the quality of the epitaxial Si layers. The electrical properties of the grown junctions were measured based on four-point probes method and analyzed using TCAD simulations on Silvaco. We demonstrate a very low resistance for the p-Si/n-GaAs junction, down to 3.10-5 .cm 2 , with current densities above 10.000 A/cm 2 , suitable for ultra-high concentration photovoltaics, largely exceeding the requirement for our low concentration targeted conditions (below 20 suns). (10.4229/EUPVSEC20152015-1CO.10.4)
  DOI : 10.4229/EUPVSEC20152015-1CO.10.4
• Electronic properties of CVD Graphene capped with p and n-type doped amorphous silicon
  
  • Arezki Hakim
  • Boutchich Mohamed
  • Alamarguy David
  • Gunes Fethullah
  • Madouri Ali
  • Alvarez J
  • Cabarrocas Pere Roca I.
  • Kleider Jean-Paul
  • Yao Fei
  • Lee Young Hee
  , 2015.
• Characterization of a-Si:H/c-Si heterojunction by temperature dependent modulated photoluminescence
  
  • Xu Ming
  • Boutchich Mohamed
  • Sobkowicz Igor Paul
  • Alvarez J
  • Brüggemann Rudolf
  • Cabarrocas Pere Roca I.
  • Kleider Jean-Paul
  , 2015.
• Characterization of graphene and applications to heterojunctions
  
  • Boutchich Mohamed
  • Kleider Jean-Paul
  • Ouerghi Abdelkarim
  • Younghee Hong-Lee
  • Lee Young Hee
  • Cabarrocas P.Roca I
  • Chen Chaoyu
  • Ávila Jose
  • Maria-Carmen Asensio
  , 2015.
• Multi-Technology Photovoltaic Module Test Bench on the Sirta Meteorological and Climate Observatory
  
  • Badosa Jordi
  • Bourdin Vincent
  • Haeffelin Martial
  • Mambrini Thomas
  • Migan-Dubois Anne
  • Nassar Joaquim
  , 2015.