S. P. Bugaev

The 100‐kV gas and metal ion source for high current ion implantation

The TITAN ion source is a new kind of source which can produce high current beams of both metal and gas ions simultaneously or separately. Ion beams of the elements Mg, Al, Ti, Ca, Cr, Fe, Co, Ni, Zn, Sn, Ta, Re, Y, C, He, N, Ar, and Xe have been generated. To obtain metal ions a vacuum arc is used in metal vapors created in ‘‘cathode spots.’’ To obtain gas ions a contragated arc discharge in gas current is used. The source extraction voltage is controlled within 10–100 kV. The ion current of both gas and metal was ≂1 A. The source operates in a frequency‐pulse regime at a pulse‐repetition frequency as high as 50 pps. At its normal operation the source provides a dose of 1016 ions/cm2 per minute on a 250‐cm2 area surface. The source is constructed according to the program on development of new technologies and is intended for high current surface modification and production of exotic surface alloys. At present, TITAN ion sources are utilized to modify physical‐mechanical parameters of different surfaces. ...

a-C:H films deposited in the plasma of barrier and surface discharges at atmospheric pressure

The aim of this work is the synthesis of the diamond-like coatings in a barrier and surface discharges at the atmospheric pressure and the investigation of their properties. The best characteristics had the coatings obtained from methane (the ratio of hydrogen atoms to carbon atoms is H/C=1.04, the ratio of the diamond-like and graphite-like C-C bonds sp 3 :sp 2 100%:0%) and from the acetylene and hydrogen mixture (1:19) (H/C=0.73, sp 3 :sp 2 = 68%:32%) in barrier discharge, as well as from methane in surface discharge (H/C =0.69-1.03, sp 3 :sp 2 =78%:22%). By their chemical and phase composition these coatings are close to the diamond-like hydrogenated (a-C:H) films obtained by traditional methods of plasma assisted chemical vapor deposition at low pressure (<10 Torr). At the same time proposed methods for fast deposition of a-C:H films make this process less expensive compared to the conventional techniques, which implies that the field of application of these films can be widened substantially.

Ion-assisted pulsed magnetron sputtering deposition of ta-C films

Abstract The process of ion-assisted deposition of ta-C films by pulsed magnetron sputtering of a graphite target has been investigated. Probe measurements of the magnetron discharge plasma have been performed and its space- and time-dependent characteristics have been obtained as functions of the sputtering parameters and the bias voltage applied to the substrate. It has been shown that the density of the pulsed magnetron discharge plasma approaches values typical of pulsed laser or vacuum arc cathode sputtering of graphite (1017−1018 m−3). Raman scattering was used to examine the ta-C films produced at both low and high pulsed bias voltages applied to the substrate (Usub

Plasma-Chemical Conversion of Lower Alkanes with Stimulated Condensation of Incomplete Oxidation Products

Oxidative conversion of a mixture of natural gas and oxygen in a barrier-discharge plasma-chemical reaction was investigated experimentally. The process was conducted at atmospheric pressure and room temperature. The discharge was initiated by high-voltage pulses of 50–100 μs duration at a repetition frequency of up to 2 kHz. The principal feature of the process was that in the plasma-chemical reactor conditions were created which stimulated the condensation of the products of incomplete oxidation of methane that resulted in the formation of aerosol even from nonsaturated vapor. The removal of intermediate reagents from the gaseous phases into the aerosol prevented them from further oxidation. Depending on the experimental conditions, the mass percentage of the components of the condensate formed varied within the following limits: formic acid from 20 to 40%, methanol from 8 to 15%, methylformate from 4 to 8%, and water from 40 to 60%. The conversion process has been realized on a laboratory setup of average power up to 1 kW. In the single-pass mode, a 57% degree of conversion of the mixture has been achieved. The energy value of the condensate is 15–20 kWh/kg.

Production of large-area coatings on glasses and plastics

Abstract This article describes an extended DC magnetron with a cylindrical cathode. The magnetron design provides for sputtering the cathode material on two opposite sides, allowing one to deposit coatings simultaneously on two plane substrates of area up to 2×3 m2. An extended ion source of magnetron type designed for cleaning and modification of the substrate surface prior to coating deposition is described as well. The characteristics of low-emissivity coatings on glasses and of conductive coatings on plastics are given. An electric circuit for pulsed power of a magnetron sputtering system, based on an artificial pulse-forming line, is proposed. The results of experiments where diamond-like films were deposited on large-area substrates by the method of pulsed magnetron sputtering of a graphite target synchronized with a pulsed high-voltage bias applied to the substrate are presented.

Properties of diamondlike films obtained in a barrier discharge at atmospheric pressure

Diamondlike films are synthesized from gaseous hydrocarbons in a barrier discharge at atmospheric pressure. The films were investigated using transmission electron microscopy, electron diffraction, and infrared spectroscopy. A technique for determining the quantitative characteristics of the films (hydrogen content, ratio of different types of carbon-carbon bonds and hydrocarbon groups) using standard samples is described. The highest-quality films were obtained from methane (ratio of hydrogen to carbon atoms H/C=1.04, fraction of diamondlike to graphitelike bonds sp3: sp2=100%: 0%) and from a mixture of acetylene and hydrogen in the ratio 1:19 (H/C=0.73, sp3: sp2=68%: 32%).

Deposition of highly adhesive amorphous carbon films with the use of preliminary plasma-immersion ion implantation

Abstract The usability of the following two types of plasma generators for deposition of highly adhesive a-C:H films on the large area substrates has been studied: (1) a source of plasma generated by means of a non-self-sustained arc discharge in low-pressure gas; and (2) an ion-plasma source on the basis of a Hall current accelerator with closed electron drift. The distinctive features of both sources are: (a) the possibility of the generation of extended flows (up to 2 m) of relatively dense plasma (∼10 10 cm −3 ); and (b) control of the plasma ionization degree, allowing realization of both preliminary plasma-immersion ion implantation (PIII) of a substrate and subsequent plasma-immersion ion-assisted deposition (PIID) of a-C:H film. The results of experimental investigations into the characteristics of the sources in different operational regimes are presented. Taking into account the probe measurements of plasma parameters, both generators have been optimized to operate in the PIII and PIID regimes. Characteristics of the pulsed negative bias applied to the substrate in both regimes have also been determined. It was shown that both sources allowed deposition of a diamond-like film on large-area substrates with a growth rate of 100–300 nm h −1 . A hard (20–30 GPa) a-C:H coating containing approximately 60% of carbon atoms with sp 3 hybridization and having satisfactory adhesion to the substrate can be obtained if short (∼60 μs) high-voltage (∼6 kV) bias pulses are applied to the substrate.

Use of the hydrocarbon plasma of a low-pressure arc discharge for deposition of highly adhesive a-C:H films

Abstract It has been investigated whether a source of a hydrocarbon plasma generated by a non-self-sustained low-pressure arc discharge is suitable for production of highly adhesive a-C:H films. The distinguishing feature of this plasma source is the possibility for varying the degree of plasma ionization and the degree of destruction of hydrocarbon gases, making possible to realize both pure plasma-immersion ion implantation (PIII) and plasma-immersion ion deposition (PIID) in a unified vacuum cycle. The plasma parameters were measured with probes as functions of discharge current. Based on these measurements, the parameters of plasma generator have been determined for the PIII and PIID operation. The parameters of the pulsed bias voltage applied to the substrate in the process of the ion implantation and growth of an a-C:H film have also been preliminary chosen. For PIID it has been demonstrated that the improvements in quality of the a-C:H coating and in its adherence to the substrate are attained when an energy per carbon atom built in the coating is lying in the range 200–500 eV. The growth rates of a-C:H films in this case are approximately 200–300 nm/h. It was shown that the most favorable for achieving high energies per deposited carbon atom and for reducing of residual intrinsic stress are short (∼60 μs) high-voltage (>1 kV) substrate bias pulses.

Phase transformations in Mo under simultaneous implantation of metal and gas ions

Abstract Phase transformations of molybdenum under ion implantation with metal and gas ions have been studied by means of transmission electron microscopy. It is shown that, as a result of ion mixing of the surface-adsorbed gas elements of the ion source, thin (⩽ 100 nm) solid layers of the interstitial phases may be formed in the ion-implanted layers. The mechanisms of formation of the structure found are discussed by investigating the crystallographic details of phase transformations.

Amorphous hydrogenated carbon films deposited by a closed-drift ion source

The general possibility of the extended (∼30 cm) closed-drift ion source application for deposition of wear-resistant amorphous hydrogenated carbon (a-C:H) films on large-area dielectric substrates, in particular, on carbon-fiber plastic, is shown. Parameters of the “ion” and the “plasma” regimes of the ion source operation in argon and methane are defined. It is shown that the ion current nonuniformity is in the range of ±5–15% depending on the operation mode. Optimum conditions for the substrate precleaning in argon and hard, well-adhered a-C:H films deposition from methane are determined. The films are characterized by high hardness (∼11 GPa) and low surface roughness (∼0.13 nm) that leads to a several times lower friction coefficient (0.05) and wear rate (0.001 μm 3 m −1 N −1 ) compared to glass and carbon-fiber plastic substrates.