| 1. |
- Greczynski, Grzegorz, et al.
(author)
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Control of the metal/gas ion ratio incident at the substrate plane during high-power impulse magnetron sputtering of transition metals in Ar
- 2017
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In: Thin Solid Films. - : ELSEVIER SCIENCE SA. - 0040-6090 .- 1879-2731. ; 642, s. 36-40
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Journal article (peer-reviewed)abstract
- High-power impulse magnetron sputtering (HiPIMS) of materials systems with metal/gas-atom mass ratios m(Me)/m(g) near, or less than, unity presents a challenge for precise timing of synchronous substrate-bias pulses to select metal-ion irradiation of the film and, thus, reduce stress while increasing layer density during low-temperature growth. The problem stems from high gas-ion fluxes Fg+(t) at the substrate, which overlap with metal-ion fluxes FMe+(t). We use energy-and time-dependent mass spectrometry to analyze FMe+(t) and Fg+(t) for Group IVb transition-metal targets in Ar and show that the time-and energy-integrated metal/gas ion ratio NMe+/NAr+ at the substrate can be controlled over a wide range by adjusting the HiPIMS pulse length tau(ON), while maintaining the peak target current density J(T,peak) constant. The effect is a consequence of severe gas rarefaction which scales with J(T)(t). For Ti-HiPIMS, terminating the discharge at the maximum J(T)(t), corresponding to tau(ON) = 30 mu s, there is an essentially complete loss of Ar+ ion intensity, yielding NTi+/NAr+ similar to 60. With increasing tau(ON),J(T)(t) decreases and NTi+/NAr+ gradually decays, due to Ar refill, to similar to 1 with tau(ON) = 120 s. Time-resolved ion-energy distribution functions confirm that the degree of rarefaction depends on tau(ON): for shorter pulses, tau ONHTC/SUBTAG amp;lt; FORTITLEHTC_RETAIN 60 [rs, the original sputtered-atom Sigmund-Thompson energy distributions are preserved long after the HiPIMS pulse, which is in distinct contrast to longer pulses, tau(ON) amp;gt;= 60 mu s, for which the energy distributions collapse into narrow ther-malized peaks. Thus, optimizing the HiPIMS pulse width minimizes the gas-ion flux to the substrate independent of m(Me)/m(g).
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| 2. |
- Greczynski, Grzegorz, 1973-, et al.
(author)
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Gas rarefaction effects during high power pulsed magnetron sputtering of groups IVb and VIb transition metals in Ar
- 2017
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In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films. - : American Institute of Physics (AIP). - 0734-2101 .- 1520-8559. ; 35:6
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Journal article (peer-reviewed)abstract
- The authors use energy- and time-dependent mass spectrometry to analyze the evolution of metal- and gas-ion fluxes incident at the substrate during high-power pulsed magnetron sputtering (HiPIMS) of groups IVb and VIb transition-metal (TM) targets in Ar. For all TMs, the time-and energy-integrated metal/gas-ion ratio at the substrate plane NMe+/NAr+ increases with increasing peak target current density J(T,peak) due to rarefaction. In addition, NMe+/NAr+ exhibits a strong dependence on metal/gas-atom mass ratio m(Me)/m(g) and varies from similar to 1 for Ti (m(Ti)/m(Ar) = 1.20) to similar to 100 for W (m(W)/m(Ar) = 4.60), with J(T,peak) maintained constant at 1 A/cm(2). Time-resolved ion-energy distribution functions confirm that the degree of rarefaction scales with m(Me)/m(g): for heavier TMs, the original sputtered-atom Sigmund-Thompson energy distributions are preserved long after the HiPIMS pulse, which is in distinct contrast to lighter metals for which the energy distributions collapse into a narrow thermalized peak. Hence, precise timing of synchronous substrate-bias pulses, applied in order to reduce film stress while increasing densification, is critical for metal/gas combinations with m(Me)/m(g) near unity, while with m(Me)/m(g) amp;gt;amp;gt; 1, the width of the synchronous bias pulse is essentially controlled by the metal-ion time of flight. The good agreement between results obtained in an industrial system employing 440 cm(2) cathodes and a laboratory-scale system with a 20 cm(2) target is indicative of the fundamental nature of the phenomena.
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| 3. |
- Greczynski, Grzegorz, et al.
(author)
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Time evolution of ion fluxes incident at the substrate plane during reactive high-power impulse magnetron sputtering of groups IVb and VIb transition metals in Ar/N-2
- 2018
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In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films. - : A V S AMER INST PHYSICS. - 0734-2101 .- 1520-8559. ; 36:2
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Journal article (peer-reviewed)abstract
- Reactive transition-metal (TM) nitride film growth employing bias-synchronized high power impulse magnetron sputtering (HiPIMS) requires a detailed knowledge of the time evolution of metal-and gas-ion fluxes incident at the substrate plane in order to precisely tune momentum transfer and, hence, provide the recoil density and energy necessary to eliminate film porosity at low deposition temperatures without introducing significant film stress. Here, the authors use energy- and time-dependent mass spectrometry to analyze the evolution of metal-and gas-ion fluxes at the substrate plane during reactive HiPIMS sputtering of groups IVb and VIb TM targets in Ar/N-2 atmospheres. The time-and energy-integrated metal/gas ion ratio NMe+/Ng+ incident at the substrate is significantly lower for group IVb TMs (ranging from 0.2 for Ti to 0.9 for Hf), due to high N-2 reactivity which results in severely reduced target sputtering rates and, hence, decreased rarefaction. In contrast, for less reactive group VIb metals, sputtering rates are similar to those in pure Ar as a result of significant gas heating and high NMe+/Ng+ ratios, ranging from 2.3 for Cr to 98.1 for W. In both sets of experiments, the peak target current density is maintained constant at 1 A/cm(2). Within each TM group, NMe+/N(g+)scales with increasing metal-ion mass. For the group-VIb elements, sputtered-atom Sigmund-Thompson energy distributions are preserved long after the HiPIMS pulse, in contradistinction to group-IVb TMs for which the energy distributions collapse into narrow thermalized peaks. For all TMs, the N+ flux dominates that of N-2(+) ions, as the molecular ions are collisionally dissociated at the target, and N+ exhibits ion energy distribution functions resembling those of metal ions. The latter result implies that both N+ and Me+ species originate from the target. High-energy Ar+ tails, assigned to ionized reflected-Ar neutrals, are observed with heavier TM targets. Published by the AVS.
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| 4. |
- Hellgren, Niklas, et al.
(author)
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High-power impulse magnetron sputter deposition of TiBx thin films : Effects of pressure and growth temperature
- 2019
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In: Vacuum. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0042-207X .- 1879-2715. ; 169
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Journal article (peer-reviewed)abstract
- Titanium boride, TiBx thin films are grown in pure Ar discharges by high-power impulse magnetron sputtering (HiPIMS) from a compound TiB2 target Film compositions are determined by time-of-flight elastic recoil detection analysis and Rutherford backscattering spectrometry as a function of deposition temperature (T-s = 25-900 degrees C) and Ar pressure (p(Ar) = 0.67-2.67 Pa, 5-20 mTorr). For reference, films are also grown by direct current magnetron sputtering (dcMS) under similar conditions. The HiPIMS waveform, average target power P-T, and resulting film compositions are strongly dependent not only on P-Ar, but also on T-s. At high pressures the effect of varying T-s on P-T is minimal, while at lower P-Ar the effect of T-s is more pronounced, due to substrate-temperature-induced gas rarefaction. Films grown by HiPIMS at 0.67 Pa are understoichiometric, with B/Ti = 1.4-1.5, while at 2.67 Pa, B/Ti decreases from 2.4 to 1.4 as T-s increases from 25 to 900 degrees C. dcMS-deposited films are overstoichiometric (B/Ti similar or equal to 3) when grown at low pressures, and near-stoichiometric (B/Ti similar or equal to r 1.9-2.2) for higher P-Ar. All experimental results are explained by differences in the ionization potentials of sputtered Ti and B atoms, together with P-Ar- and T-s-dependent gas-phase scattering.
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| 5. |
- Hellgren, Niklas, et al.
(author)
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High-power impulse magnetron sputter deposition of TiBx thin films : Effects of pulse length and peak current density
- 2024
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In: Vacuum. - : Elsevier. - 0042-207X .- 1879-2715. ; 222
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Journal article (peer-reviewed)abstract
- We report on a systematic study of the effect of pulse length (ton=25−200μs), and peak target current density (JT,peak=0.25−2.0A/cm2) during HiPIMS deposition of AlB2-phase TiBx thin films from a TiB2 target at a pressure of pAr=1.33Pa(10mTorr) and substrate temperature Ts=500°C. All films are under-stoichiometric with B/Ti = 1.36–1.89, with the higher values corresponding to longer pulses and higher JT,peak values. While the deposition flux, including both ions and neutrals, in general increases with increasing ton and JT,peak, the Ti+ ion flux saturates, resulting in the higher B/Ti values under these conditions. Thus, the relative amount of Ti ionization, and the degree to which these ions are guided toward the substrate by magnetic fields, are main modulators determining the composition of TiBx thin films.
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| 6. |
- Kholodnaya, G. E., et al.
(author)
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Pulsed electron beam propagation in argon and nitrogen gas mixture
- 2015
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In: Physics of Plasmas. - : AMER INST PHYSICS. - 1070-664X .- 1089-7674. ; 22:10
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Journal article (peer-reviewed)abstract
- The paper presents the results of current measurements for the electron beam, propagating inside a drift tube filled in with a gas mixture (Ar and N-2). The experiments were performed using the TEA-500 pulsed electron accelerator. The main characteristics of electron beam were as follows: 60 ns pulse duration, up to 200 J energy, and 5 cm diameter. The electron beam propagated inside the drift tube assembled of three sections. Gas pressures inside the drift tube were 760 +/- 3, 300 +/- 3, and 50 +/- 1 Torr. The studies were performed in argon, nitrogen, and their mixtures of 33%, 50%, and 66% volume concentrations, respectively. (C) 2015 AIP Publishing LLC.
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| 7. |
- Kholodnaya, Galina, et al.
(author)
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Obtaining Silicon Oxide Nanoparticles Doped with Fluorine and Gold Particles by the Pulsed Plasma-Chemical Method
- 2019
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In: Journal of Nanotechnology. - : HINDAWI LTD. - 1687-9503 .- 1687-9511.
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Journal article (peer-reviewed)abstract
- This paper presents a study on pulsed plasma-chemical synthesis of fluorine- and gold-doped silicon oxide nanopowder. The gold- and fluorine-containing precursors were gold chloride (AuCl3) and sulphur hexafluoride (SF6). Pulsed plasma-chemical synthesis is realized on the laboratory stand, including a plasma-chemical reactor and TEA-500 electron accelerator. The parameters of the electron beam are as follows: 400-450keV electron energy, 60ns half-amplitude pulse duration, up to 200J pulse energy, and 5cm beam diameter. We confirmed the composite structure of SixOy@Au by using transmission electron microscopy and energy-dispersive spectroscopy. We determined the chemical composition and morphology of synthesized SixOy@Au and SixOy@F nanocomposites. The material contained a SixOy@Au carrier with an average size of 50-150nm and a shell of fine particles with an average size of 5-10nm.
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| 8. |
- Kholodnaya, Galina, et al.
(author)
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Pulsed plasma chemical synthesis of carbon-containing titanium and silicon oxide based nanocomposite
- 2018
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In: Radiation Physics and Chemistry. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0969-806X .- 1879-0895. ; 144, s. 132-137
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Journal article (peer-reviewed)abstract
- The paper presents the results of the experimental investigation of the physical and. chemical properties of the TixSiyCzOw composite nanopowders, which were first obtained using a pulsed plasma chemical method. The pulsed plasma chemical synthesis was achieved using a technological electron accelerator (TEA-500). The parameters of the electron beam are as follows: 400-450 keV electron energy, 60 ns half-amplitude pulse duration, up to 200 J pulse energy, and 5 cm beam diameter. The main physical and chemical properties of the obtained composites were studied (morphology, chemical, elemental and phase composition). The morphology of the TixSiyCzOw composites is multiform. There are large round particles, with an average size of above 150 nm. Besides, there are small particles (an average size is in the range of 15-40 nm). The morphology of small particles is in the form of crystallites. In the TixSiyCzOw synthesised composite, the peak with a maximum of 946 cm(-1) was registered. The presence of IR radiation in this region of the spectrum is typical for the deformation of atomic oscillations in the Si-O-Ti bond, which indicates the formation of the solid solution. The composites consist of two crystal phases - anatase and rutile. The prevailing phase of the crystal structure is rutile.
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| 9. |
- Kholodnaya, G., et al.
(author)
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Study of the conditions for the effective initiation of plasma-chemical treatment of flue gas under the influence of a pulsed electron beam
- 2020
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In: Laser and particle beams (Print). - : CAMBRIDGE UNIV PRESS. - 0263-0346 .- 1469-803X. ; 38:3, s. 197-203
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Journal article (peer-reviewed)abstract
- This paper presents the results of comprehensive studies of the efficiency of a pulsed electron beam transmission through a mixture of gases: nitrogen (83%), carbon dioxide (14%), and oxygen (2.6%) in the presence of ash and water vapor. The studied concentrations correspond to the concentrations of nitrogen, oxygen, and carbon dioxide in flue gas. The pressure and concentration of water vapor and ash in the drift chamber varied (375, 560, and 750 Torr; humidity 15 +/- 5% and 50 +/- 15%). The charge dissipation of a pulsed electron beam in the gas mixture in the presence of ash and water vapor was investigated, as well as the effect of the concentration of water vapor and ash on the geometric profile of the pulsed electron beam.
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| 10. |
- Konusov, F. V., et al.
(author)
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Optical properties of carbon-containing titanium oxide nanocomposites obtained by the pulsed plasma chemical method
- 2017
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In: Fullerenes, nanotubes, and carbon nanostructures. - : TAYLOR & FRANCIS INC. - 1536-383X .- 1536-4046. ; 25:6, s. 343-347
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Journal article (peer-reviewed)abstract
- This paper presents the results of an experimental investigation on the optical properties of the TiO2 and TixCyOz nanopowders, produced by the pulsed plasma chemical method. Pulsed plasma chemical synthesis is realized on the laboratory stand, including a plasma chemical reactor (6 l) and TEA-500 electron accelerator. The parameters of the electron beam are as follows: 400-450 keV electron energy, 60 ns half-amplitude pulse duration, up to 200 J pulse energy, and 5 cm beam diameter. In TiO2 sample, obtained using the pulsed plasma chemical method, the particles can be divided into two groups: 100-500 nm large spherical particles and tiny complex particles (sized less than 100 nm). For TixCyOz sample, the morphology of the particles is mainly presented with irregular fragment shape. The average size of the particles is ranged from 200 to 300 nm. The band gap for all synthesized samples is within 2.94-3.35 eV.
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