Publications

1999

• Stable microcrystalline silicon thin-film transistors produced by the layer-by-layer technique
  
  • Roca I Cabarrocas Pere
  • Brenot Romain
  • Bulkin Pavel
  • Vanderhaghen Regis
  • Drévillon Bernard
  • French Ian
  Journal of Applied Physics, American Institute of Physics, 1999, 86 (12), pp.7079-7082. Microcrystalline siliconthin films prepared by the layer-by-layer technique in a standard radio-frequency glow discharge reactor were used as the active layer of top-gate thin-film transistors(TFTs). Crystalline fractions above 90% were achieved for silicon films as thin as 40 nm and resulted in TFTs with smaller threshold voltages than amorphous siliconTFTs, but similar field effect mobilities of around 0.6 cm2/V s. The most striking property of these microcrystalline silicontransistors was their high electrical stability when submitted to bias-stress tests. We suggest that the excellent stability of these TFTs, prepared in a conventional plasma reactor, is due to the stability of the μc-Si:H films. These TFTs can be used in applications that require high stability for which a-Si:HTFTs cannot be used, such as multiplexed row and column drivers in flat-panel display applications, and active matrix addressing of polymer light-emitting diodes. (10.1063/1.371795)
  DOI : 10.1063/1.371795
• Synthesis of Iron Carbide Based Nanopowders by Laser Photoinduced Reactions from Gaseous Precursors
  
  • Alexandrescu R.
  • Cojocaru Costel Sorin
  • Crunteanu Aurelian
  • Morjan I.
  • Voicu I.
  • Huisken F.
  • Kohn B.
  • Vasiliu F.
  • Fatu D.
  , 1999, 717, pp.463-470.
• Carbon Nitride Thin Films and Nanopowders Produced by CO2 Laser Pyrolysis
  
  • Alexandrescu R.
  • Cireasa R.
  • Cojocaru Costel Sorin
  • Crunteanu Aurelian
  • Morjan I.
  • Vasiliu F.
  • Kumar A.
  , 1999, 717, pp.321-328.
• Deposition of microcrystalline silicon in an integrated distributed electron cyclotron resonance PECVD reactor
  
  • Bulkin Pavel
  • Hofrichter A.
  • Brenot Romain
  • Drévillon Bernard
  Thin Solid Films, Elsevier, 1999, pp.37-40.
• Carbon nitride thin films and nanopowders produced by CO2 laser pyrolysis
  
  • Alexandrescu Rodica
  • Cireasa Raluca
  • Cojocaru Costel Sorin
  • Crunteanu Aurelian
  • Morjan I.
  • Vasiliu F.
  • Kumar Ashok
  Surface Engineering, Maney Publishing, 1999, 15 (3), pp.230-234. Nanocrystalline CNx particles and thin films were produced in a flow reactor system by the CO2 laser pyrolysis of sensitised NH3-N2O-C2 H2reactant gas mixtures. Depending on the substrate nature (silicon or quartz) the SEM and TED analysis of the CNx thin films revealed specific nucleation and growth morphologies of crystallites, resembling the β-C3 N4 phase. In the case of C3 N4 nanopowder synthesis, the relative concentration of the sensitisers (SF6 /C2 H4 ) was varied to minimise SF6 decomposition. The majority of the data obtained from powder analysis (XRD, XPS, and ir transmission measurements) suggests the presence of CN bonded phases and the formation of α-and β-C3 N4 structures.
• Plasma enhanced chemical vapour deposition of SiOxNy in an integrated distributed electron cyclotron resonance reactor
  
  • Hofrichter A.
  • Bulkin Pavel
  • Drévillon Bernard
  Applied Surface Science, Elsevier, 1999, pp.447-450.
• Silicon carbide nanoparticles produced by CO2 laser pyrolysis of SiH4/C2H2 gas mixtures in a flow reactor
  
  • Huisken F.
  • Kohn B.
  • Alexandrescu R.
  • Cojocaru Costel Sorin
  • Crunteanu Aurelian
  • Ledoux G.
  • Reynaud C.
  Journal of Nanoparticle Research, Springer Verlag, 1999, 1 (2), pp.293-303. Pulsed CO_2-laser-induced decomposition of different mixtures of SiH_4 and C_2H_2 in a flow reactor has been employed to produce silicon carbide clusters and nanoparticles with varying content of carbon. The as-synthesized species were extracted from the reaction zone by a conical nozzle and expanded into the source chamber of a cluster beam apparatus where, after having traversed a differential chamber, they were analyzed with a time-of-flight mass spectrometer. Thin films of silicon carbide nanoclusters were produced by depositing the clusters at low energy on potassium bromide and sapphire windows mounted into the differential chamber. At the same time, Si and SiC nanoparticles were collected in a filter placed into the exhaust line of the flow reactor. Both beam and powder samples were characterized by FTIR spectroscopy. The close resemblance of the spectra suggests that the composition of the beam and powder particles obtained during the same run is nearly identical. XRD spectroscopy could only be employed for the investigation of the powders. It was found that CO_2 laser pyrolysis is ideally suited to produce silicon carbide nanoparticles with a high degree of crystallinity. Nanopowders produced from the pyrolysis of a stoichiometric (2:1) mixture of SiH_4/C_2H_2 were found to contain particles or domains of pure silicon. The characteristic silicon features in the FTIR and XRD spectra, however, disappeared when C_2H_2 was applied in excess.
• A study of the mechanical behaviour of plasma deposited silica films on polycarbonates and steel
  
  • Hofrichter Alfred
  • Constantinescu Andrei
  • Benayoun Stéphane
  • Bulkin Pavel
  • Drévillon Bernard
  , 1999, 18 (4), pp.2012-2016. In the present study, we deposited amorphous hydrogenated silicon oxide films on polycarbonate, stainless steel, and silicon by plasma enhanced chemical vapor deposition using a low pressure, high density integrated distributed electron cyclotron resonance plasma reactor. Substrate curvature, vibrating slab, and Vickers indentation experiments were used to evaluate the intrinsic stress, the Young modulus of the films, and the composite hardness of the film–substrate system. The indentation experiments were modeled by finite element analysis and the calculated values were compared to experimentally measured hardness values. A reasonable accordance with the experiment was found both for stainless-steel and polycarbonate substrates, indicating that the modeling is valid and may be used to enhance the interpretation of the indentation experiments. The calculations show an important bending of the film in the noncontact region in the case of a Vickers indentation on a coated polycarbonate sample. The analysis of the thus-induced strain distribution in the coating indicates that the measured diagonal might be overestimated and not representative of the real contact area. The calculations indicate that the yield limit of the plasma-deposited silica films is of about 4 GPa. (10.1116/1.582464)
  DOI : 10.1116/1.582464
• Nanoparticles of Si-C-N from low temperature plasmas: selective size, composition and structure
  
  • Viera Gregorio
  • Garcia-Caurel Enric
  • Andujar José Luis
  • Bertran Enric
  Applied Surface Science, Elsevier, 1999, 144-145, pp.702.