Filtered Vacuum Arc Deposition System Research Articles

Swift heavy ion irradiation of metal containing tetrahedral amorphous carbon films

Thin carbon films were grown at room temperature on (001) n-Si substrate using dual cathode filtered vacuum arc deposition system. Graphite was used as a source of carbon atoms and separate metallic electrode was simultaneously utilized to introduce Ni or Cu atoms. Films were irradiated by 100MeV Ag7+ ions to fluences in the range 1×1010–3×1011cm−2. Rutherford backscattering spectroscopy, Raman scattering, scanning electron microscopy and atomic force microscopy in conductive mode were used to investigate film properties and structure change under irradiation. Some conductive channels having metallic conductivity type were found in the films. Number of such channels is less than number of impinged ions. Presence of Ni and Cu atoms increases conductivity of those conductive channels. Fluence dependence of all properties studied suggests different mechanisms of swift heavy ion irradiation-induced transformation of carbon matrix due to different chemical effect of nickel and copper atoms.

Properties of SnO 2 films fabricated using a rectangular filtered vacuum arc plasma source

Transparent and conducting SnO 2 films of 57–200nm thickness were deposited on microscope glass slide substrates, using a rectangular filtered vacuum arc deposition system. The 40 glass slides were equally distributed on a 400 × 420mm substrate carriage, and were exposed to a Sn plasma beam, produced by a rectangular vacuum arc plasma gun with a Sn cathode, and passed through a rectangular magnetic macroparticle filter towards the substrates. The carriage with the substrates was transported past the 94 × 494mm filter outlet. The SnO 2 films were fabricated on the glass substrates at room temperature by maintaining the chamber oxygen background pressure at 0.52Pa. The film composition, and electrical and optical properties were studied as a function of the film thickness. The films were stored under ambient air conditions, and their electrical resistance was measured as a function of storage time over a period of several months. The average resistivity of films was 10–17mΩ cm for films with thickness ( t) less than 100nm, but that of t > 100nm it was 5–9mΩ cm. The resistivity of the films with t > 100nm did not change significantly after 8months of storage in ambient air. The optical transmittance of the films in the visible spectrum was in the range of 75–90%. The optical constants, i.e., the refractive index and the extinction coefficient of the films at wavelength λ = 550nm were in the range of 2.02–2.09 and 0.013–0.023, respectively, and the optical band gap energy was 4.15–4.21eV. Unlike the electrical resistivity, the optical parameters weakly depended on t.

Chemical and thermal stability of the characteristics of filtered vacuum arc deposited ZnO, SnO2 and zinc stannate thin films

ZnO, SnO2 and zinc stannate thin films were deposited on commercial microscope glass and UV fused silica substrates using filtered vacuum arc deposition system. During the deposition, the substrate temperature was at room temperature (RT) or at 400 °C. The film structure and composition were determined using x-ray diffraction and x-ray photoelectron spectroscopy, respectively. The transmission of the films in the VIS was 85% to 90%. The thermal stability of the film electrical resistance was determined in air as a function of the temperature in the range 28 °C (RT) to 200 °C. The resistance of ZnO increased from ∼ 5000 to 105 Ω when heated to 200 °C, that of SnO2 films increased from 500 to 3900 Ω, whereas that of zinc stannate thin films increased only from 370 to 470 Ω. During sample cooling to RT, the resistance of ZnO and SnO2 thin films continued to rise considerably; however, the increase in the zinc stannate thin film resistance was significantly lower. After cooling to RT, ZnO and SnO2 thin films became practically insulators, while the resistance of zinc stannate was 680 Ω. The chemical stability of the films was determined by immersing in acidic and basic solutions up to 27 h. The SnO2 thin films were more stable in the HCl solution than the ZnO and the zinc stannate thin films; however, SnO2 and zinc stannate thin films that were immersed in the NaOH solution did not dissolve after 27 h.

The dependence of filtered vacuum arc deposited ZnO–SnO2 thin films characteristics on substrate temperature

ZnO–SnO2 thin films were deposited by filtered vacuum arc deposition system and characterized using x-ray diffraction (XRD), energy dispersive spectroscopy, atomic force microscopy (AFM), spectrophotometer and ex situ variable angle spectroscopic ellipsometry. According to the XRD analysis the films were amorphous, independent of the deposition conditions. The root-mean-squares (RMS) of surface roughness and the average grain size obtained from the AFM images were 0.2–0.8 nm and 15–20 nm, respectively. Averaged optical transmission was 85%, and the refractive index and extinction coefficient of the films were in the range 2.05–2.28 and 0.001–0.044 at 500 nm wavelength, respectively. The range of the optical band gap of the films was 3.43–3.70 eV, depending on deposition conditions. The lowest resistivity was of the order of 10−2 Ω cm for films deposited on 400 °C heated substrates, while films deposited on substrates at room temperature were non-conducting, and films on 200 °C heated substrates were weakly conducting(∼101–2 Ω cm). The resistivity of films decreased with increasing pressure for 200 and 400 °C heated substrates relative to RT deposited films. The effect of deposition conditions on the optical constants was analysed statistically by single and two sided variance analysis, using the analysis code ‘Analysis Of Variance’ to determine the significance of the differences between sets.

Filtered vacuum arc deposition of transparent conducting Al-doped ZnO films

Transparent conducting ZnO:Al and ZnO films of 380–800 nm thickness were deposited on glass substrates by filtered vacuum arc deposition (FVAD), using a cylindrical Zn cathode doped with 5–6 at.% Al or a pure Zn cathode in oxygen background gas with pressure P = 0.4–0.93 Pa. The crystalline structure, composition and electrical and optical properties of the films were studied as functions of P. The films were stored under ambient air conditions and the variation of their resistance as function of storage time was monitored over a period of several months. The Al concentration in the film was found to be 0.006–0.008 at.%, i.e., a few orders of magnitude lower than that in the cathode material. However, this low Al content influenced the film resistivity, ρ, and its stability. The resistivity of as-deposited ZnO:Al films, ρ = (6–8) × 10 − 3 Ω cm, was independent of P and lower by a factor of 2 in comparison to that of the ZnO films deposited by the same FVAD system. The ρ of ZnO films 60 days after deposition increased by a factor of ∼ 7 with respect to as-deposited films. The ZnO:Al films deposited with P = 0.47–0.6 Pa were more stable, their ρ first slowly increased during the storage time (1.1–1.4 times with respect to as-deposited films), and then stabilized after 30–45 days.

Effect of deposition conditions on the characteristics of ZnO–SnO 2 thin films deposited by filtered vacuum arc

ZnO–SnO 2 thin films were deposited on microscope glass substrates by filtered vacuum arc deposition system. The effects of deposition conditions on film characteristics were studied using cathodes prepared with three different ratios of atomic concentrations of Zn to Sn. The micro and the macro properties of the films were investigated as a function of cathode composition, arc current, background oxygen deposition pressure, and deposition time. X-ray diffraction analysis indicated that deposited films were amorphous, independent of the cathode composition. The atomic concentration ratio of Zn to Sn in the film as determined by XPS analysis were 33.9%: 10.6%, 43.9%: 3.8%, 44.7%: 4.7% for 50%: 50%, 70%: 30% and 90%: 10% Zn–Sn alloy cathodes, respectively. Film transmission in the visible was 70 to 90%, affected by interference effects. The maximal and minimal values of the refractive index n and the absorption coefficient k in the visible were 2.11 to 1.94 and 0.07 to 0.001, respectively. The optical band gap was in the range of 3.13 to 3.59 eV. All films were highly resistive independent of deposition conditions used.

Growth of ZnO nanorods by air annealing of ZnO films with an applied electric field

A novel method of ZnO nanorods growth is presented based on low temperature (300 °C) air annealing of ZnO film while applying an electric field (∼10 V/cm) parallel to the film. The films were deposited on glass substrates using a filtered vacuum arc deposition system equipped with a Zn cathode, at an arc current of 160 A, oxygen pressure of 3.2 mTorr, and deposition time of 30 s. Cu tape electrodes were applied on each end of the coated sample, and used to apply the electric field. The samples were annealed in a quartz furnace at 200, 300, 400 °C for 20 or 60 min. Each sample surface was examined using a Scanning Electron Microscope (SEM) and a High Resolution SEM (HRSEM) to study its micro- and nano-structure. The film crystallographic structure was studied using X-ray diffractometry (XRD). ZnO rods with lengths of ∼3 μm were observed on the samples annealed at 300 °C for 20 min with an electric field of ∼103 V/m, while separated conical forms with lengths of ∼0.5 μm and base width of ∼150 nm were observed after annealing under the same conditions but without any electric field. The rod growth rate and area density were ∼2.0–2.5 nm/s, and ∼3×107 cm−2, respectively.

Microstructure and magnetic properties of FePt:Ag nanocomposite films on SiO 2/Si(1 0 0)

FePt:Ag nanocomposite films were prepared by pulsed filtered vacuum arc deposition system and subsequent rapid thermal annealing on SiO 2/Si(1 0 0) substrates. The microstructure and magnetic properties were investigated. A strong dependence of coercivity and ordering of the face-central tetragonal structure on both Ag concentration and annealing temperature was observed. With Ag concentration of 22% in atomic ratio, the coercivity got to 6.0 kOe with a grain size of 6.7 nm when annealing temperature was 400 °C.

Air annealing effects on the optical properties of ZnO–SnO2 thin films deposited by a filtered vacuum arc deposition system

ZnO–SnO2 transparent and conducting thin films were deposited on microscope glass substrates by a filtered vacuum arc deposition (FVAD) system. The cathode was prepared with 50%:50% atomic concentration of Zn:Sn. The films were annealed in air at 500 °C for 1 h. Structural and compositional analyses were obtained using XRD and XPS diagnostics. X-ray diffraction analysis indicated that as-deposited and air-annealed thin ZnO–SnO2 films were amorphous. The atomic ratio of Zn to Sn in the film obtained using the 50%:50% cathode as determined by XPS analysis was ∼2.7:1 in the bulk film. The optical properties were determined from normal incidence transmission measurements. Film transmission in the visible was 70% to 90%, affected by interference effects. Annealed films did not show higher transmission in the VIS compared to as-deposited films. Assuming that the interband electron transition is direct, the optical band gap was found to be in the range 3.34–3.61 eV for both as-deposited and annealed films. However, the average Eg for annealed films was 3.6 eV, larger by 0.2 eV than that of as-deposited. The refractive index n increased while the extinction index k decreased significantly with annealing.

Dependence of zinc oxide thin film properties on filtered vacuum arc deposition parameters

The micro-properties (structure and composition) and macro-properties (electrical and optical properties) of zinc oxide thin films deposited on glass substrates using a filtered vacuum arc deposition system were investigated as a function of oxygen pressure (0.37–0.5 Pa) and arc current (100–300 A). The films were polycrystalline and the crystal plane orientation varied with the oxygen pressure and arc current, tending to be aligned parallel to the c-axis. The sizes of the crystallite grains were 10–35 nm. The films were found to be compressively stressed, with stress in the range of −2.5–0 GPa. The stress in any sample decreased as a function of arc current; however, its dependence on the pressure also depended on the applied arc current. The compressive stress in samples deposited with arc current in the range 100–150 A, decreased with the pressure from −2.5 to −1.5 GPa (0.37–0.5 Pa), whereas it increased with the oxygen pressure in samples deposited with arc current ranging from 200–300 A. The compressive stress in all samples deposited with the highest oxygen pressure (0.51 Pa) was in a relatively narrow range of −2.1 to −1.7 GPa.Film composition, determined by x-ray photoelectron spectroscopy, depended weakly on the deposition parameters. All samples had zinc excess, with a typical oxygen to zinc atomic concentration ratio of 0.7–0.8. Film thickness, in the range of 80–780 nm, depended linearly on both the deposition parameters.The electrical resistivity (ρ) of the films was in the range of (1–5) × 10−4 Ωm, depending weakly on the deposition parameters. The electrical resistivity of the films with larger grain size was higher than that of films with smaller grains, whereas it increased with film stress. The optical transmission of the films, expressed by the extinction coefficient, depended strongly on both the deposition parameters (arc current and oxygen pressure). The lowest extinction was obtained with films deposited with higher pressure (P ⩽ 0.5 Pa) and lower arc current (I ⩾ 200 A). The lowest extinction coefficient was ∼4 × 10−4 nm−1 in the visible and the near-IR range of the spectrum. Films with larger grain size and lower stress had a relatively larger extinction coefficient (∼8 × 10−3 nm−1).

Electro-optical and structural properties of thin ZnO films, prepared by filtered vacuum arc deposition

Thin ZnO films were deposited at room temperature on glass substrates by a filtered vacuum arc deposition system. The electrical, optical and structural properties were investigated as a function of the oxygen pressure in the range of 0.26–0.73 Pa and arc current in the range of 100–300 A. No additional treatment was applied to the samples. Film thickness was in the range of 100–400 nm, depending linearly on the arc current. As-deposited electrical resistivity was in the range of (1–2)×10 −4 Ω m and the optical transmission of 300-nm-thick films was in the range of 85–95% in the visible and near-IR spectral region. Minimal resistivity of 1.05×10 −4 Ω m was obtained for a 240-nm-thick film, which had ∼94% transmittance in the visible and near-IR range, and which was deposited at 0.42-Pa oxygen pressure. The relative standard deviation of the measured parameters, determined on a set of seven samples deposited with the same current and pressure was less than 4%. XPS analysis showed that the films were non-stoichiometric both on the surface and within the film, and that the composition was weakly pressure dependent. X-ray diffraction analysis showed the films to be crystalline, with a pressure dependent preferred orientation.

Field electron emission characteristics of nitrogenated tetrahedral amorphous carbon films

The electron field emission characteristics of the nitrogenated tetrahedral amorphous carbon (ta-C:N) films deposited by a pulsed filtered vacuum arc deposition system at various conditions were investigated. The wider region of N content in the films (0–21 at.%) allow us to study systematically the effects of N content and the other related parameters on field emission characteristics of the films. It was found that the field emission for both batches of ta-C:N samples depended upon the N content and this effect dominated the effects of the other parameters, such as sp 3 content, resistivity of the films, band gap of the films, and Fermi level position. The threshold field was found to first increase with increasing N content up to 5 at.%, then started to decrease up to a minimum of approximately 4 V/μm at 10 at.%. When the N content became higher than 10 at.%, the threshold field was found to increase again. Such complicated variation of the threshold field with the N content of the ta-C:N films was discussed in terms of a three-step field emission model.

Synthesis and structure of nitrogenated tetrahedral amorphous carbon thin films prepared by a pulsed filtered vacuum arc deposition

Nitrogenated tetrahedral amorphous carbon (ta-C:N) thin films have been prepared by a pulsed filtered vacuum arc deposition system at various conditions. The chemical composition and structure of the ta-C:N films were investigated by Non-Rutherford backscattering spectroscopy, Auger electron spectroscopy, Raman, and Fourier transform infrared transmission measurements. It was observed that the amount of N atoms incorporated into the ta-C:N films, as well as the fraction and size of the sp 2 clusters, increased with increasing nitrogen pressure during deposition. On the other hand, the substrate negative bias voltage has different effects on the composition and structure of the films. The N content initially rises with increasing substrate negative bias voltage and then starts to decrease as it is further increased, while the sp 2 fraction increases monotonically with the increase of negative bias voltage. No or very few CN bond exists in the films. With increasing N content the components of the single CN and disorder activated CC diminish. The compressive stress in the films is found to decrease sharply with the increase of nitrogen content, and then keep almost constant when the N content is increased further.

Optical properties of nitrogenated tetrahedral amorphous carbon films

The chemical composition, structural, and optical properties of nitrogenated tetrahedral amorphous carbon (ta-C:N) films deposited by a pulsed filtered vacuum arc deposition system were characterized by non-Rutherford backscattering spectroscopy, Raman spectroscopy, and ultraviolet-visible spectroscopy. It was observed that the amount of nitrogen atoms incorporated into the ta-C:N films, as well as the sp2 fraction of the films, increased with increasing nitrogen pressure PN during deposition. As a result, the optical band gap of the ta-C:N films also decreased with increasing PN. At a fixed nitrogen partial pressure of 4×10−3 Pa, the nitrogen content was found to first increase with increasing substrate negative bias voltage (−Us), up to a maximum of about 14.5 at. % at −Us of 100 and 150 V, then decreases with further increase of −Us. The sp2 fraction however increased monotonically with increasing −Us. The optical band gap of the ta-C:N films initially increased with increasing −Us, up to a maximum at a certain −Us, and then decreased with further increase in −Us. The variation of the optical band gap with the negative substrate bias voltage was discussed in terms of the different sp2-bonded carbon configurations existing in the films and the graphitization of the ta-C:N films, as indicated by the Raman and density measurement results.

XPS of Ti+TiN+(N,C) multilayer films deposited by filtered cathodic arc deposition with controlled feed gas flow rate

Abstract Ti+TiN+Ti(N,C) films are deposited in a filtered vacuum arc deposition system by controlling the gas inlet order and gas flow rate, with a steady increase of C 2 H 2 and a steady decrease of N 2 flow rate. X-ray photoelectron spectroscopy (XPS) has been used to analysis the element depth profile. The C1s, N1s and Ti2p spectra are discussed.

Macroparticle distribution in a quarter-torus plasma duct of a filtered vacuum arc deposition system

The macroparticle (MP) flux distribution in a quarter-torus filtered vacuum arc deposition system was experimentally investigated and compared with theoretical predictions based on a previously developed model. The average MP flux was measured by collecting the MPs generated from a Ti cathode on substrates located at different radial positions on the entrance and the exit planes of the quarter-torus filter, and measuring the MP size distribution function using an automated microscopic image analysis system. The average MP flux along the torus centre line decreased by a factor of 50 from the entrance to the exit, while the average MP flux decrease near the outer wall of the torus was more moderate. The flux near the outer wall was greater by a factor of three than the centreline flux. Increasing the toroidal magnetic field from 4 to 10 mT resulted in no substantial change in the MP flux on the centreline, while near the outer wall it decreased by a factor of two. The experimental results on the MP flux in the near outer wall region are consistent with electrostatic reflection of the charged MPs by the charged wall.

Ion current distribution within a toroidal duct of a filtered vacuum arc deposition system

Vacuum arcs were established on a 90-mm-diameter Ti cathode in a deposition apparatus consisting of a spacer, 122 mm-diameter annular anode, quarter-torus magnetic macroparticle filter, and a deposition chamber. A toroidal magnetic field generally parallel to the torus walls of up to 20 mT was applied. The ion current in various cross-sections of the toroidal duct was measured using: 1) a disc probe of 130-mm diameter, oriented normal to the torus axis used to measure the transmitted ion current, and 2) a hollow cylindrical probe of 135-mm diameter and 25-mm height, whose axis coincided with the torus axis, used to measure ion current losses to the duct wall. The distribution of ion current loss was studied using an 8-segment hollow cylindrical multiprobe, where the individual probes were equally distributed on the circumference of a 130-mm-diameter circle. It was shown that: 1) the ratio of ion currents collected on the cylindrical and disc probes at first decreases with increasing the toroidal field, and then becomes approximately constant; 2) the presence of the large-diameter disc probe does not influence the value of the ion current on the cylindrical probe; and 3) the maximum ion current density near the torus walls is located in the +g direction and displaces in the -(B/spl times/g) direction with increasing the toroidal field, where g and B are the vectors of the centrifugal acceleration and the magnetic field, respectively.

Influence of gas pressure on the ion current and its distribution in a filtered vacuum arc deposition system

A filtered vacuum arc deposition system consisted of a cathode, an annular anode, a quarter torus duct macroparticle filter, and a deposition chamber. Arcs were sustained on a Ti cathode in the presence of noble background gases helium and argon, and reactive gases nitrogen and oxygen. The gas pressure was continuously varied from 3 × 10 −5 Torr (4 mPa) to 0.1 Torr (13.3 Pa). A toroidal magnetic field of up to 20 mT, and a straight field in the deposition chamber of up to 10 mT were imposed for plasma guiding. The total saturation ion current was measured with a 130 mm diameter probe. The ion current density distribution was measured with a nine-segment multi-probe, and the individual probe element currents were fitted to a two-dimensional Gaussian distribution. It was shown that in the presence of a noble gas the total saturation ion current at first increases with increasing the background gas pressure, then achieves a maximum at a pressure of 10 mTorr (1.3 Pa) for He, and at 2 mTorr (0.26 Pa) for Ar, where its value is 1.4–2 times greater than in vacuum. With further increase in the pressure the ion current strongly decreases. In the presence of reactive gases this maximum is not observed, and the total ion current strongly decreases at pressures greater than 2–3 mTorr (0.26–0.4 Pa). In contrast to this, a maximum is observed in the ion current collected on small diameter individual probes of multi-probe, positioned towards the direction of the plasma beam displacement. With increasing gas pressure, the distribution width decreases, and a displacement of the beam center is observed both in the − g direction and in the ( B × g) direction, where B and g are vectors of the toroidal field and centrifugal acceleration, respectively. The present results show that proper substrate positioning in the deposition chamber must take into account the beam displacement due to the background gas.

Ion current distribution in a filtered vacuum arc deposition system

The ion current distribution produced by a filtered vacuum arc deposition system consisting of a 90-mm diameter cathode, 122-mm internal diameter anode, and a 240-mm major radius / 80-mm minor radius quarter-torus duct macroparticle filter was measured with a nine-element multi-probe, and the total ion current was measured with a 130-mm diameter probe. Arcs were sustained on Ti and Sn cathodes, with currents of 300–340 and 160–175 A, respectively. Radial magnetic fields of up to 3 mT were imposed on the cathode surface for cathode spot rotation, and fields of up to 20 mT generally parallel to the duct were imposed for plasma guiding. In general, the plasma distribution function exiting from the duct was approximately Gaussian, but with an offset from the center of the duct. At the torus exit, the Ti plasma beam was offset 12 mm towards the outside of the torus at B = 4 mT, while with increasing toroidal field the beam center moved towards the center of the duct, and reached the center at B = 8 mT. The beam was offset towards the inside of the torus for B > 8 mT, reaching a displacement of up to 5 mm for B = 12 mT. The Sn beam, by contrast, was shifted towards the inside of the torus, and the displacement from the center was as much as 15 mm. In addition, for both cases an offset in the (B × g) direction was observed, where B is the duct magnetic field vector and g is a vector pointing outward from the toroidal center of curvature. The displacements from the center were stronger for Sn plasma (up to 16 mm) than for Ti plasma (up to 7 mm). The displacement from the center in both directions grew with the distance from the exit of the torus. A beam steering coil, whose axis was normal to the axis of plasma duct, was used to shift the plasma beam center towards the chamber axis.

Ion current distribution in a filtered vacuum arc deposition system

The ion current distribution produced by a filtered vacuum arc deposition system consisting of a 90-mm diameter cathode, 122-mm internal diameter anode, and a 240-mm major radius / 80-mm minor radius quarter-torus duct macroparticle filter was measured with a nine-element multi-probe, and the total ion current was measured with a 130-mm diameter probe. Arcs were sustained on Ti and Sn cathodes, with currents of 300–340 and 160–175 A, respectively. Radial magnetic fields of up to 3 mT were imposed on the cathode surface for cathode spot rotation, and fields of up to 20 mT generally parallel to the duct were imposed for plasma guiding. In general, the plasma distribution function exiting from the duct was approximately Gaussian, but with an offset from the center of the duct. At the torus exit, the Ti plasma beam was offset 12 mm towards the outside of the torus at B = 4 mT, while with increasing toroidal field the beam center moved towards the center of the duct, and reached the center at B = 8 mT. The beam was offset towards the inside of the torus for B > 8 mT, reaching a displacement of up to 5 mm for B = 12 mT. The Sn beam, by contrast, was shifted towards the inside of the torus, and the displacement from the center was as much as 15 mm. In addition, for both cases an offset in the (B × g) direction was observed, where B is the duct magnetic field vector and g is a vector pointing outward from the toroidal center of curvature. The displacements from the center were stronger for Sn plasma (up to 16 mm) than for Ti plasma (up to 7 mm). The displacement from the center in both directions grew with the distance from the exit of the torus. A beam steering coil, whose axis was normal to the axis of plasma duct, was used to shift the plasma beam center towards the chamber axis.