TY - JOUR A1 - Kornev, R. A1 - Gornushkin, Igor B. A1 - Nazarov, V. A1 - Shkrunin, V. A1 - Ermakov, A. T1 - Features of hydrogen reduction of SiF4 in ICP plasma JF - Spectrochimica Acta Part B N2 - Probe diagnostics is used to determine the electron temperature and electron number density in a low pressure inductively coupled plasma (ICP) ignited in the mixture of SiF4, Ar and H2. Emission spectra of mixtures with different stoichiometry of components are investigated and the electron density distribution function (EDDF) is estimated. The optimal conditions for high conversion of SiF4 into Si are found by studying the dependence of the yield of silicon upon the ratio of reagents. The maximum achieved yield of silicon is 85% under the optimal conditions. Based on the analysis of IR and MS spectra of exhaust gases, 5% of initial SiF4 converts into volatile fluorosilanes. A rate of production of Si is 0.9 g/h at the energy consumption 0.56 kWh /g. KW - Plasma enhanced chemical vapor deposition KW - PECVD KW - Silicon tetrafluoride KW - Emission spectroscopy KW - Probe diagnostics PY - 2022 DO - https://doi.org/10.1016/j.sab.2022.106502 SN - 0584-8547 VL - 195 SP - 106502 PB - Elsevier B.V. AN - OPUS4-55316 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kornev, R. A. A1 - Sennikov, P. G. A1 - Gornushkin, Igor B. A1 - Ermakov, A. A. A1 - Shkrunin, V. E. A1 - Polykov, V. S. A1 - Kornev, A. R. A1 - Kornev, K. D. T1 - Laser induced dielectric breakdown as a novel method for the synthesis of molybdenum boride JF - Plasma chemistry and plasma processing N2 - Laser induced dielectric breakdown (LIDB) on a surface of solid Mo in H2/BF3 atmosphere at 30-760 Torr and in a gaseous mixture MoF6/H2/BF3 + at 760 Torr pressure is tested for synthesis and deposition of superhard molybdenum borides that are needed in many areas of industry and technology. The emission spectra of the plasma and the dynamics of the gas discharge near the substrate are investigated. A comparative analysis of the gas mixture before and after exposure to LIDB plasma is carried out using IR spectroscopy. The conditions for the formation of molybdenum borides are determined. A thermodynamic analysis of the MoF6/H2/BF3 and Mo/H2/BF3 systems is carried out to determine the temperature range for the formation of molybdenum borides and establish the main chemical reactions responsible for their formation. Deposits containing MoB and MoB2 phases are obtained. For the mixture MoF6/H2/BF3, the deposit exhibits an amorphous layered structure, which contains 19.15 wt% F, 30.45% O, and 0.8% Si. For the Mo/H2/BF3 system at the pressures 30 and 160 Torr, nanopowder of molybdenum boride is produced with a characteristic grain size of 100 nm. At pressures above 160 Torr, Mo nanopowder with a grain size <30 nm is obtained. KW - LIDB plasma KW - MoF6 KW - BF3 KW - Hydrogen reduction KW - Molybdenum boride PY - 2022 DO - https://doi.org/10.1007/s11090-021-10224-0 SN - 1572-8986 SP - 1 EP - 18 PB - Springer CY - Dordrecht AN - OPUS4-54290 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sennikov, P. A1 - Ermakov, A. A1 - Kornev, R. A1 - Gornushkin, Igor B. T1 - Laser induced dielectric breakdown in reactive mixture SiF4 + H2 JF - Spectrochimica Acta Part B N2 - Important chemical process of reduction of SiF4 by hydrogen is realized in laser induced dielectric breakdown (LIDB) plasma in a gas mixture of SiF4 and H2. The process may be an alternative to a method of Plasma enhanced chemical vapor deposition (PECVD) which is commonly used for production of pure and isotopically pure silicon films. The composition of laser induced plasma in gases SiF4, SiF4 + H2, SiF4 + H2 + Ar at atmospheric pressure is studied and compared to the composition of inductively coupled plasma (ICP) in the same gases but at reduced pressure of 3 Torr. The gaseous products of chemical reactions are inferred from optical emission spectroscopy (OES) and IR spectroscopy. The reaction products of silicon fluoride SiF and fluorosilanes SiHxFy (x, y = 1, 2, 3) in LIDB plasma are observed and confirmed by equilibrium chemistry calculations and simulations of plasma expansion dynamics using a fluid dynamic-chemical plasma model. It is further suggested that chemisorption of fluorinated species like SiFx (x = 1, 2) followed by the surface reaction with H-atoms lead to a formation of silicon-to‑silicon bonds on a substrate surface. A conclusion is drawn that energetic laser induced plasma can prove efficient for one-step PECVD by hydrogen reduction of SiF4. KW - Silicon halides KW - Chemical vapor deposition KW - Laser induced dielectric breakdown KW - Hydrogen reduction PY - 2021 DO - https://doi.org/10.1016/j.sab.2021.106099 VL - 179 SP - 106099 PB - Elsevier B.V. AN - OPUS4-53583 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gornushkin, Igor B. A1 - Sennikov, P. A1 - Kornev, R. A1 - Ermakov, A. A1 - Shkrunin, V. T1 - Laser Induced Dielectric Breakdown for Chemical Vapor Deposition by Hydrogen Reduction of Volatile Boron Halides BCl3 and  BF3 JF - Plasma Chemistry and Plasma Processing N2 - A possibility of deposition from laser-induced plasma is investigated in search for an economic and simple method for obtaining isotopic compounds from enriched gaseous precursors although no isotopic compounds are used in this the proof-of-principle work. A breakdown in mixtures of BCl3 and BCl3 with hydrogen, argon, and methane are studied both theoretically and experimentally. Equilibrium chemistry calculations show the deposition of boron, boron carbide, and carbon is thermodynamically favorable in BCl3 systems and only carbon in BF3 systems. Dynamic calculation of expanding plasma is performed using fluid dynamics coupled with equilibrium chemistry. Condensed phases of boron, boron carbide, and graphite are predicted with maximum concentrations in peripheral zones of the plasma. In experiment, plasma is induced in mixtures BCl3, H2 + BCl3, H2 + Ar + BCl3, H2 + BCl3 + CH4, BF3, H2 + BF3, H2 + Ar + BF3, and H2 + Ar + BF3. The gases are analyzed before, during, and after laser irradiation by optical and mass spectrometry methods. The results show the composition of reaction products close to that predicted theoretically. The conversion of precursor gases BCl3 and BF3 into gaseous and condensed products is 100% for BCl3 and 80% for BF3. Solid deposits of up to 30 mg are obtained from all reaction mixtures. Due to technical reasons only FTIR characterization of the BCl3 + H2 + CH4 deposit is done. It points to presence of condensed boron and boron carbide predicted by the model. Overall, the calculations and preliminary experimental results imply the chemical vapor deposition with laser induced plasma is promising for conversion of gaseous enriched precursors into elemental isotopes and their isotopic compounds. KW - Boron halides KW - Chemical vapor deposition KW - Laser induced dielectric breakdown, Hydrogen reduction PY - 2020 DO - https://doi.org/10.1007/s11090-020-10096-w VL - 40 IS - 5 SP - 1145 EP - 1162 PB - Springer AN - OPUS4-50968 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gornushkin, Igor B. A1 - Sennikov, P. A1 - Kornev, R. A1 - Ermakov, A. A1 - Shkrunin, V. A1 - Polyakov, V. T1 - Laser induced dielectric breakdown for synthesis of chlorofluorosilanes JF - Journal of Fluorine Chemistry N2 - Tetrafluorosilane (SF4) and tetrachlorosilane (SiCl4) plasmas have been widely used as a source of either F or Cl for etching silicon or as a source of silicon for deposition of Si-based materials. Using different combinations of F and Cl in molecules of chlorofluorosilane SiFxCly adds additional flexibility in realization of these processes. Direct synthesis of SiFxCl4-x (x=1, 2, 3) from SiF4 and SiCl4 is thermodynamically forbidden under standard conditions. This restriction is removed in low-temperature plasmas studied in this work: a laser induced dielectric breakdown (LIDB) plasma and steady-state inductively-coupled plasma (ICP). The plasmas differ in many respects including energy content, temperature, and electron density that lead to different ionization/excitation states of plasma species, which are observed from plasma optical emission spectra. IR spectroscopy and mass-spectrometry confirm the formation of three chlorofluorosilanes, SiF3Cl, SiF2Cl2, and SiFCl3 that constitute ~60% in products of LIDB plasma and split 50/50 between SiF3Cl, SiFCl3 and SiF2Cl2. Experimental observations are verified by equilibrium static calculations via the minimization of Gibbs free energy and by dynamic calculations via the chemical-hydrodynamic plasma model of a spherically expanding plasma plume. The both types of calculations qualitatively agree with the results of spectroscopic analysis and reproduce dominant presence of SiF2Cl2 as the temperature of the gas approaches the room temperature. KW - Chemical-hydrodynamic modeling KW - Chlorofluorosilanes KW - Laser induced dielectric breakdown KW - Inductively coupled plasma KW - Equilibrium chemical modeling PY - 2020 DO - https://doi.org/10.1016/j.jfluchem.2020.109692 VL - 241 SP - 109692 PB - Elsevier B.V. AN - OPUS4-51646 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -