Publications

2005

• Physico-Chimie des plasmas de silane pour la formation de nacocristaux de silicium a tempétature ambiante : application à des dispositifs.
  
  • Suendo Veinardi
  , 2005. Information technology has grown rapidly in the last few decades and is becoming one of the basic needs of humankind. As this technology grows, the demand for new materials to develop it also increases. So far, silicon is the main semiconductor material for electronic applications, while III-V semiconductors are the main materials for photonic applications. We readily find silicon integrated circuits (ICs) around us: in our cellular phones, personal computers, cars, home appliances, etc. For the further development of this technology, a material compatible with silicon microelectronics and suitable optoelectronic properties would play an important role. In particular, research should focus on a material which could be used for the next generation of photon emitters and could be integrated directly into an IC. Indeed, it is well-known that due to its indirect band-gap structure, bulk silicon is an extremely inefficient photon emitter. Therefore, scientists have turned their interests to other more complex and expensive semiconductor materials such as GaAs (gallium arsenide), InP (indium phosphide), GaP (gallium phosphide), etc. Even though these materials have allowed the realization of laser diodes, they cannot be easily associated with silicon integrated circuits. They are incompatible because the two materials have different crystal lattice constants, a socalled lattice mismatch. Another type of materials, which also give good luminescent efficiency are organic materials. In this case, one does not encounter the lattice mismatch problem due to their amorphous structure, but their processing into devices is not always compatible with microelectronics industry standards. Moreover, the stability of these materials is quite low compared to their inorganic counterparts.
• Hydrogen storage by adsorption on activated carbon: experimental and numerical study
  
  • Hermosilla-Lara Guillaume
  • Momen Gelareh
  • Marty Philippe
  • Hassouni Khaled
  , 2005, pp.pas précise.
• Hopping current density in reversely biased crystalline silicon / amorphous carbon heterojunctions
  
  • Katsuno T.
  • Godet C.
  • Loir A.-S.
  • Garrelie Florence
  , 2006, 352 (9-20), pp.1421-1424. High density amorphous carbon (a-C) films deposited by femtosecond pulsed laser ablation were incorporated in p-type c-Si/a-C/Al devices. Rectifying I–V characteristics were measured versus temperature T (200–300 K). At low fields, the conductivity behaves as Ln (σ/σ∘∘) = −(T0/T)1/4, corresponding to 3D hopping transport. As the electric field F increases from 104 to 105 V cm−1, the decrease of both apparent slope from 230 to 100 K1/4 and prefactor σ∘∘(F) from 1016 to 104 S cm−1 is quantitatively similar for forward and reverse bias, with however a shift ΔV of 0.28 eV attributed to the heterojunction built-in potential. The observed strong decrease in the apparent prefactor σ∘∘(F) is consistent with recent modeling of field-enhanced hopping transport in exponential band tails. (10.1016/j.jnoncrysol.2005.09.038)
  DOI : 10.1016/j.jnoncrysol.2005.09.038
• Experimental and numerical study of the hydrogen's storage by adsorption on activated carbon
  
  • Hermosilla-Lara Guillaume
  • Hassouni Khaled
  • Marty Philippe
  • Momen Gelareh
  , 2005, pp.pas precisé.
• Conformal anodic oxidation of aluminum thin films
  
  • Cojocaru C. S.
  • Padovani J.M.
  • Wade T.
  • Mandoli C.
  • Jaskierowicz G.
  • Wegrowe J. -E.
  • Morral A.F.I.
  • Pribat Didier
  Nano Letters, American Chemical Society, 2005, 5 (4), pp.675-680. Membrane-based synthesis, also called template synthesis, is a very general approach used to prepare arrays of nanomaterials with monodispersed geometrical features. The most commonly used porous templates are track-etched polycarbonate and porous anodic alumina membranes. Common to all these templates is the fact that the pores are perpendicular to the surface of the membrane. Here, a novel approach is presented, where the pores are synthesized parallel to the surface of the membrane. For the first time, the anodic oxidation of an aluminum thin film is performed laterally, i.e., parallel to the surface of the substrate, instead of perpendicular as usually done. For low anodic oxidation voltages (between 3 and 5 V) we obtain highly regular and ordered pore arrays, at least over a few hundred nanometers length, with a minimum pore size of similar to 3 to 4 nm. With such porous alumina structures, the controlled in-plane organization of arrays of template-grown nanowires and carbon nanotubes for reproducible device fabrication should be much easier. (10.1021/nl050079b)
  DOI : 10.1021/nl050079b
• FTIR ellipsometry device and process for characterization and further identification of samples of complex biological materials, notably micro-organisms
  
  • Garcia-Caurel Enric
  • Drevillon Bernard
  • Schwartz Laurent
  , 2005.
• About the efficiency limits of heterojunction solar cells
  
  • Damon-Lacoste J.
  • Roca I Cabarrocas Pere
  • Chatterjee P.
  • Veschetti Y.
  • Gudovskikh A.S.
  • Kleider J.P.
  • Ribeyron P.J.
  , 2005.
• Spectroscopic study using FTIR, Raman, XPS and NEXAFS of carbon nitride thin films deposited by RF magnetron sputtering
  
  • Bouchet-Fabre B.
  • Marino E.
  • Lazar G.
  • Zellama K.
  • Clin M.
  • Ballutaud D.
  • Abel F.
  • Godet C.
  Thin Solid Films, Elsevier, 2005, 482, Issues 1-2, pp.167-171. The spectroscopic study of a-CNx thin films deposited by R.F. magnetron sputtering is reported. The bonding structure was determined using FTIR, Raman Scattering, NEXAFS and XPS results. The combination of the FTIR and Raman spectroscopy using the vibrational properties and the XPS and NEXAFS using the electronic properties of the materials is useful for a good description of the local structure in carbon nitride. The investigation is focused on the effect of the RF power and substrate temperature on the nitrogen surrounding in carbon nitride thin films. A good correlation is observed between the evolution of the π* electron states as calculated from NEXAFS, the evolution of the sp2 bonding of carbon observed in XPS, and the evolution of the electrical and optical properties of the films. These results combined with FTIR and Raman analysis and the elemental composition determined by nuclear microanalysis allow to follow the evolution of the local structure with the deposition conditions in a-CNx films. (10.1016/j.tsf.2004.11.166)
  DOI : 10.1016/j.tsf.2004.11.166
• Optical thin films deposition by MDECR-PECVD
  
  • Haj Ibrahim Bicher
  • Bulkin Pavel
  • Daineka D.
  • Drevillon Bernard
  , 2005, pp.59631Q.
• Optical properties of high-density amorphous carbon films grown by nanosecond and femtosecond pulsed laser ablation
  
  • Katsuno Takashi
  • Godet Christian
  • Orlianges J.C.
  • Loir A.-S.
  • Garrelie Florence
  • Catherinot Alain
  Applied physics. A, Materials science & processing, Springer Verlag, 2005, 81 (31), pp.471-476. High-density tetrahedral amorphous carbon (ta-C) films have been prepared by nanosecond (17 ns) and femtosecond (150 fs) pulsed laser deposition (PLD) using fluences and repetition rates compatible with fast and homogeneous growth over large areas. Their optical properties were measured by spectroscopic ellipsometry from 1.0 to 4.7 eV and analyzed using a multi-layer Tauc-Lorentz model. In spite of very different ablation mechanisms, both PLD techniques produce high density bulk layers as revealed by a refractive index (n at 2 eV) of 2.7±0.1 for both fs-PLD and ns-PLD. Films are covered by a few nm-thick sp2-rich top layer which is denser and thicker in femtosecond PLD as compared to nanosecond PLD. The respective roles of low and high energies in the kinetic energy distribution of the incident carbon species are discussed in terms of densification and sp3 →sp2 configurational relaxation predicted by the subplantation growth model. The significantly higher optical gap found in the ns-PLD films is attributed to the larger contribution of energetic species with kinetic energies Ec ≥ 200 eV, as revealed by time-of-flight optical studies. (10.1007/s00339-005-3257-6)
  DOI : 10.1007/s00339-005-3257-6
• Growth dynamics of hydrogenated silicon nanoparticles under realistic conditions of a plasma reactor
  
  • Vach H.
  • Brulin Q.
  • Chaâbane N.
  • Novikova T.
  • Roca I Cabarrocas Pere
  • Kalache B.
  • Hassouni K.
  • Botti Silvana
  • Reining Lucia
  Computational Materials Science, Elsevier, 2005, 35, pp.216-222. We present results of an extensive numerical study that was motivated by the experimental problem to understand under which conditions SinHm nanoparticles deposited by plasma enhanced chemical vapor deposition (PECVD) take an amorphous or a crystalline structure. A crystalline structure of those particles is crucial, for example, for the electrical properties and lifetime of polymorphous solar cells. First, we use a fluid dynamics model to characterize the experimentally employed silane plasma. The resulting relative densities for all plasma radicals, their temperatures, and their collision interval times are then used as input data for detailed semiempirical quantum molecular dynamics simulations. As a result the growth dynamics of nanometric hydrogenated silicon SinHm clusters is simulated starting out from the collision of individual SiHx radicals under the plasma conditions derived above. We demonstrate how the details of the plasma determine the amorphous or crystalline character of the forming nanoparticles. Finally, we show a preliminary absorption spectrum based on ab initio time-dependent DFT calculations for a crystalline Si10H16 cluster to demonstrate the possibility to monitor the cluster growth in situ. (10.1016/j.commatsci.2004.07.010)
  DOI : 10.1016/j.commatsci.2004.07.010
• Comparative study of the structure of a-CNx and a-CNx:H films using NEXAFS, XPS and FT-IR analysis
  
  • Bouchet-Fabre B.
  • Zellama K.
  • Godet C.
  • Ballutaud D.
  • Minéa T.
  Thin Solid Films, Elsevier, 2005, 482, Issues 1-2, pp.156-166. Amorphous carbon nitride thin films have become a matter of great attention due to their remarkable electronic and mechanical properties. It has been shown that hydrogen and nitrogen incorporation deeply modifies the properties of carbon films. Therefore, the optimization of their properties requires a deep knowledge of various kind of chemical bonds composing in the film matrix. The topic of this presentation is to get more insight into the different local environment of the C and N atoms for hydrogenated and hydrogen-free amorphous carbon nitrides films. H-incorporation has been varied using different deposition technique from plasma-enhanced chemical vapor deposition (PECVD) leading to highly hydrogenated films up to 40 at.% to radio-frequency (RF) magnetron sputtering providing nearly hydrogen-free films. The study of the local structure is done using the combination of Fourier transform infrared (FT-IR), X-ray photo-emission spectroscopy (XPS) and high resolution near edge X-ray absorption fine structure (NEXAFS) analysis. FT-IR spectroscopy is widely used to probe the bonding configurations in the carbonaceous materials, especially the CN, CH and NH bonds in a-CNx:H. In addition, XPS and NEXAFS provide surface information on the environment around C and N atoms and on the chemical composition. NEXAFS gives a better description of the π* states inside the films, due to its remarkable energy resolution. The combination of both characterizations FT-IR and NEXAFS may leave the controversy about the interpretation of the XPS spectra, and allows a fine analysis of the evolution of the local structure as a function of nitrogen incorporation, according to the hydrogen concentration into the films. Fundamental differences can be revealed between hydrogenated and hydrogen-free carbon nitride: in the former, hydrogen promotes double bonds CNH, whereas in the latter nitrogen atoms prefer to substitute to carbon or interconnect aromatic rings through single bonds (>CN). A strong conjugation of imines (NCNH) for PECVD film and nitrile (NCN) groups for hydrogen-free films is evidenced. (10.1016/j.tsf.2004.11.134)
  DOI : 10.1016/j.tsf.2004.11.134
• Interface properties of a-Si:H/c-Si heterojunction solar cells from admittance spectroscopy
  
  • Gudovskikh A.S.
  • Kleider J.P.
  • Damon-Lacoste J.
  • Roca I Cabarrocas Pere
  • Veschetti Y.
  • Muller J.C.
  • Ribeyron P.J.
  • Rolland E.
  , 2005.
• Metrological applications of Mueller polarimetry in conical diffraction for overlay characterization in microelectronics
  
  • Novikova Tatiana
  • de Martino Antonello
  • Ossikovski Razvigor
  • Drevillon Bernard
  European Physical Journal: Applied Physics, EDP Sciences, 2005, 31, pp.63.