Cathodic arc plasma deposition of nano-multilayered ZrN/AlSiN thin films

Thin films of ZrN/AlSiN were deposited on SKD 11 tool steel substrate using Zr and AlSi cathodes in an Ar/N₂ gas mixture in a cathodic arc plasma deposition system. The influence of the AlSi cathode arc current and the substrate bias voltage on the mechanical and structural properties of the films was investigated. X-ray diffraction, electron probe micro-analysis, high resolution transmission electron microscopy, nanoindentation and profilometry were used to characterize the films. The ZrN/AlSiN thin films had a multilayered structure by rotating the substrate in which nano-crystalline ZrN layers alternated with amorphous AlSiN layers. The hardness of the films increased as the AlSi cathode arc current was raised from 35 to 40 A, and then decreased with a further increase of the current. The hardness of the films increased with the increase of the bias voltage from − 50 to − 100 V. Further increase in the bias voltage decreased the hardness. The films exhibited a maximum hardness of 38 GPa. With the increase of bias voltage, the residual stress of the films correlated well with the hardness.     

Deposition of nanolayered CrN/AlBN thin films by cathodic arc deposition: Influence of cathode arc current and bias voltage on the mechanical properties

Thin films of CrAlBN were deposited on SKD 11 tool steel substrate using Cr and AlB cathodes in a cathodic arc plasma deposition system. The influence of AlB cathode arc current and substrate bias voltage on the mechanical and the structural properties of the films was investigated. The CrAlBN thin films had a multilayered structure in which the nano-crystalline CrN layer alternated with the amorphous AlBN layer. The hardness of the films increased as the AlB cathode arc current was raised from 35 to 45 A, and then decreased with further increase of the current. The hardness of the films increased rapidly with the increase of the bias voltage from − 50 to − 150 V. Further increase in the bias voltage decreased the hardness. The maximum hardness of 48 GPa was obtained at the bias voltage of − 150 V. With the increase of bias voltage, a good correlation between the residual stress and the hardness of the films was observed.     

Al and Zn film deposition using a vacuum arc plasma source with a refractory anode

The radially expanding plasma plume generated in a Hot Refractory Anode Vacuum Arc was used to deposit thin Al and Zn films on glass substrates. The electrode separation was 10 mm, arc time varied up to 165 s, and current (I) was 100-225 A. The cathode was a water-cooled Al or Zn cylinder. A graphite anode with 9 or 30 mm height was used with the Al cathode, and 10 or 30 mm height Mo anode was used with the Zn cathode. A mechanical shutter controlled the substrate exposure onset and duration (15 s) to the anodic plasma. The distance from the arc axis to the substrate (L) was varied between 80 and 165 mm. The film thickness was measured with a profilometer, and macroparticle (MP) presence on the coating surface was examined by optical microscopy.It was found that the deposition rate increased as a function of time to a peak, and then decreased to a steady-state value. The peak occurred sooner using the 9 mm anode than with the 30 mm anode. The peak deposition rate increased and the peak time decreased with I. The steady-state deposition rate was larger for Zn (~ 2 μm/min) than for Al cathodes (~ 1 μm/min) at I = 225 A and L = 110 mm. The arc voltage for Al was ~ 20-22 V and for Zn it was 11 V. The deposition rate peak appeared due to MPs evaporating from the hot anode, where they had initially condensed during the conventional arc stage when the anode was still cold. This effect was significant with low melting temperature Al and Zn cathodes, and negligible with Cu and Ti cathodes studied previously.     

Mechanical properties of high-density diamond like carbon (HD-DLC) films prepared using filtered arc deposition

Because high density DLC (HD-DLC) films prepared using filtered arc deposition (FAD) systems possess high hardness, low friction coefficients, and a smooth surface, they have been good candidates for use in tribological applications. The aim of present work is the investigation of the mechanical and structural properties of HD-DLC films.The experimental conditions were the following: arc current, 50 A; base pressure, less than 3 × 10^− 3 Pa; substrate bias, DC-100 V; substrate temperature, less than 100 °C. The HD-DLC films were formed on silicon wafers and tungsten carbide (WC) substrates. The film properties of hardness, composition, structure, and friction were analyzed.The film hardness is high, 80-90 GPa, with a low friction coefficient of less than 0.1.     

The effect of applied substrate negative bias voltage on the structure and properties of Al-containing a-C:H thin films

Al-containing hydrogenated amorphous carbon (Al-C:H) films were prepared using a magnetron sputtering Al target in the CH₄ and Ar mixture atmosphere with various applied substrate pulse negative bias voltages. The hydrogen content and internal stress of the film decrease dramatically with the substrate pulse bias voltage increase. However, the hardness values of the films keep at high level (∼ 20 GPa) without any obvious changes with the increase of the applied substrate pulse bias voltages. The Al-C:H film prepared at applied substrate high bias voltage shows a long wear life and low friction coefficient.     

Layer formation by resputtering in Ti-Si-C hard coatings during large scale cathodic arc deposition

This paper presents the physical mechanism behind the phenomenon of self-layering in thin films made by industrial scale cathodic arc deposition systems using compound Ti-Si-C cathodes and rotating substrate fixture. For the as-deposited films, electron microscopy and energy dispersive X-ray spectrometry reveals a trapezoid modulation in Si content in the substrate normal direction, with a period of 4 to 23 nm dependent on cathode configuration. This is caused by preferential resputtering of Si by the energetic deposition flux incident at high incidence angles, when the substrates are facing away from the cathodes. The Ti-rich sub-layers exhibit TiC grains with sizes up to 5 nm, while layers with high Si-content are less crystalline. The nanoindentation hardness of the films increases with decreasing layer thickness.     

Filtered vacuum arc deposition of undoped and doped ZnO thin films: Electrical, optical, and structural properties

Filtered vacuum (cathodic) arc deposition (FVAD, FCVD) of metallic and ceramic thin films at low substrate temperature (50-400 °C) is realized by magnetically directing vacuum arc produced, highly ionized, and energetic plasma beam onto substrates, obtaining high quality coatings at high deposition rates. The plasma beam is magnetically filtered to remove macroparticles that are also produced by the arc. The deposited films are usually characterized by their good optical quality and high adhesion to the substrate. Transparent and electrically conducting (TCO) thin films of ZnO, SnO₂, In₂O₃:Sn (ITO), ZnO:Al (AZO), ZnO:Ga, ZnO:Sb, ZnO:Mg and several types of zinc-stannate oxides (ZnSnO₃, Zn₂SnO₄), which could be used in solar cells, optoelectronic devices, and as gas sensors, have been successfully deposited by FVAD using pure or alloyed zinc cathodes. The oxides are obtained by operating the system with oxygen background at low pressure. Post-deposition treatment has also been applied to improve the properties of TCO films.The deposition rate of FVAD ZnO and ZnO:M thin films, where M is a doping or alloying metal, is in the range of 0.2-15 nm/s. The films are generally nonstoichiometric, polycrystalline n-type semiconductors. In most cases, ZnO films have a wurtzite structure. FVAD of p-type ZnO has also been achieved by Sb doping. The electrical conductivity of as-deposited n-type thin ZnO film is in the range 0.2-6 × 10^− 5 Ω m, carrier electron density is 10²³-2 × 10²⁶ m^− 3, and electron mobility is in the range 10-40 cm²/V s, depending on the deposition parameters: arc current, oxygen pressure, substrate bias, and substrate temperature. As the energy band gap of FVAD ZnO films is ∼ 3.3 eV and its extinction coefficient (k) in the visible and near-IR range is smaller than 0.02, the optical transmission of 500 nm thick ZnO film is ∼ 0.90.     

Microstructure, mechanical and electrochemical properties evaluation of pulsed DC reactive magnetron sputtered nanostructured Cr-Zr-N and Cr-Zr-Si-N thin films

Cr-Zr-Si-N thin films with various Zr contents were deposited by a bipolar asymmetric pulsed DC reactive magnetron sputtering system. In addition, a Cr-Zr-N film without Si addition was fabricated as a reference. The influence of Zr on the constitution, microstructure, mechanical, tribological and electrochemical properties of Cr-Zr-Si-N films was investigated. The microstructure of thin films was determined by a glancing angle X-ray diffractometer (GA-XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), respectively. A nanoindenter, a Vickers micro hardness tester and pin-on-disk wear tests were adopted to evaluate the hardness, toughness and tribological properties of thin films, respectively. The electrochemical properties of thin films were also evaluated in 3.5 wt.% NaCl aqueous solution. In case of the Cr-Zr-Si-N films, the Si content was fixed around 6-8 at.% and various Zr contents ranging from 0.5 to 13.6 at.% were achieved by changing the Zr target power density. In comparison to the Cr-Zr-N reference film, the addition of ~ 7.0 at.% Si in Cr-Zr-Si-N films resulted in a refined columnar structure and enhanced mechanical and anti-corrosion properties. A lattice constant expansion of these films was observed with increasing Zr content. A nanostructured thin film with around 5-10 nm grain size was obtained in case of a Cr-13.6 at.% Zr-6.8 at.% Si-N film. In general, the hardness, plastic deformation resistance and corrosion resistance increased also with increasing Zr content in the Cr-Zr-Si-N films. The Cr-Zr-Si-N film containing 13.6 at.% Zr exhibited a combination of high hardness, good mechanical properties, adequate tribological performance and excellent corrosion resistance in this study.     

LiCoO2 cathode thin film fabricated by RF sputtering for lithium ion microbatteries

Thin films of lithium cobalt oxide were deposited on Pt or Pt/Ti/quartz glass substrates by radio frequency (RF) magnetron sputtering at the substrate temperatures from room temperature to 500 °C. As the substrate temperature increased, the film structure changed from amorphous structure to crystallinity with a strong (003) texture as characterized by X-ray diffraction. The surface morphology and cross-section were observed using scanning electron microscopy. It was found that the films tended to crack at a high substrate temperature. Charge-discharge tests of these films were conducted and compared. The different electrochemical characteristics of these films were attributed to the modified crystallography, morphology, and thermal stress. The LiCoO₂ film deposited at 400 °C showed a well-defined 4.0 V voltage plateau on charge and a 3.9 V plateau on discharge, and delivered 54.5 μAh/cm² μm at the first discharge capacity, with good cycling performance, giving evidence that such films could be used as the thin film cathodes for lithium microbatteries.     

Structure and properties of Ti–Al–Y–N coatings deposited from filtered vacuum-arc plasma

Ti_0.5Al_0.5N coatings with a small amount of Y (up to 1 at.%) were deposited by filtered vacuum arc plasma at pulsed high voltage negative substrate bias potential with amplitude up to 2.5 kV and their microstructure was studied. X-ray fluorescence analysis showed that this deposition method allows ensuring well the conformity of the elemental composition of the metallic components of cathodes and films. X-ray diffraction measurements of the films with yttrium revealed a solid solution (Ti,Al)N phase with a cubic NaCl-type structure as the only crystalline phase. The films deposited with an amplitude of the substrate bias potential in the range of 1–1.5 kV were characterized by a strong axial texture [110]. In these films an increase of the yttrium content leads to the reduction of the nitride lattice parameter and growth of coherent scattering zone dimension as well as to a decrease of the surface roughness. Coatings containing 1 at.% Y exhibited high hardness of 32–36 GPa and oxidation resistance.     

Study on nanocrystalline Cr2O3 films deposited by arc ion plating: I. composition, morphology, and microstructure analysis

Nanocrystalline Cr₂O₃ thin films were deposited on silicon wafers with (100) orientation by arc ion plating (AIP) technique at various negative bias voltages. By virtue of X-ray diffraction analysis, scanning electron microscope, and high-resolution transmission electron microscope, the influence of substrate bias voltage on the film growth process, microstructure, and characteristics was investigated systematically, including the phase constituents, grain size, lattice constant, chemical compositions, as well as surface and cross-section morphologies. With increasing the bias voltage, the grain size and lattice constant of AIP Cr₂O₃ films first decreased slightly, and then increased gradually again. Both reached the minimum (35 nm and 13.57 Å) when the bias voltage was − 100 V. However, the bias voltage had little effect on the phase constituents and chemical compositions of AIP Cr₂O₃ films. During the film growth process, the surfaces of Cr₂O₃ films were getting smoother with the negative bias voltage increase, in the meantime, their microstructures evolved from coarse columnar grains to fine columnar grains, short columnar recrystallized grains, and fine columnar grains again.     

Structural and mechanical stability upon annealing of arc-deposited Ti-Zr-N coatings

Ti-Zr-N coatings were formed by the method of vacuum arc deposition using combined Ti and Zr plasma flows in a N₂ atmosphere at different ratios of arc currents of Ti and Zr cathodes. After deposition, obtained samples were annealed in vacuum at the temperature of 850 °C. The element and phase composition, residual stresses and nanohardness were studied by Auger-Electron Spectroscopy, X-ray diffraction (XRD) and nanoindentation, respectively.XRD analysis reveals the formation of ternary Ti-Zr-N nitride coatings with the structure of solid solutions. It is shown that Ti-Zr-N coatings possess high hardness in comparison with TiN and ZrN binary nitrides. An increase in hardness is observed with increasing Zr content. However, it is established that after annealing coatings keep better stability of hardness with decrease of Zr content. The intrinsic stress in the as-deposited coatings is found to be largely compressive (− 4 GPa) and almost independent of Zr content, but much higher than in ZrN and TiN binary nitrides (− 2 GPa). After annealing, a significant stress relaxation is observed in all coatings due to relief of growth-induced point defects. Stress analysis on as-grown and annealed samples enabled us to determine the stress-free lattice parameter a₀. This latter is expanded by ∼ 0.4-0.7% as compared to Vegard's law.The thermal stability of Ti-Zr-N coatings will be discussed in terms of evolution and interdependence between structure, composition and hardness after annealing.     

Effect of substrate bias in amorphous carbon films having embedded nanocrystallites

The effect of substrate bias on the structural, morphological, electrical and mechanical properties of amorphous carbon (a―C) films having embedded nanocrystallites deposited by filtered cathodic jet carbon arc technique has been investigated. X-ray diffraction exhibits predominantly an amorphous nature of the film. High resolution transmission electron microscope investigations reveal largely an amorphous structure. However, an ultra-fine nanograined microstructure with the average grain size between 20 and 50 nm was observed throughout the entire film and the majority of the individual grains were single crystallites with the preferred interplanar spacing of about 0.2 nm. All the parameters evaluated were seen to depend strongly on the negative substrate bias and exhibit maxima or minima in the properties of the films deposited at − 150 V substrate bias. These a-C films having embedded nanocrystallites act as hard coating materials.     

Preparation of ZrO<Subscript>2</Subscript> dielectric layers by subsequent oxidation after Zr film deposition with negative substrate bias voltage

ZrO₂ dielectric layers were prepared by a two-step process, a deposition of pure Zr film with and without a negative substrate bias voltage and a subsequent oxidation of the Zr films. We focused on the effect of the negative substrate bias voltage on the Zr film deposition and the subsequent oxidation of the Zr films. As a result, the Zr film deposited at the substrate bias voltage of −50 V (Vs = −50 V) was found to have a high intensity peak of Zr (100) and a uniform and smooth surface. From the capacitance-voltage and current-voltage measurements of the ZrO₂ films, a high dielectric constant of 21 and the equivalent oxide thickness (EOT) of 2.6 nm were obtained on the oxidation layer of the Zr film deposited at Vs = −50 V. On the other hand, a low dielectric constant of 15 and the EOT of 3.6 nm was obtained on that of the Zr film deposited at Vs = 0 V. The leakage current density of the ZrO₂ film (Vs = −50 V) was 5.69×10⁻⁴ A/cm², and this value was much lower than the 1.21×10⁻⁴ A/cm² for the ZrO₂ film (Vs = 0 V). It was found that the two-step process by subsequent oxidation after film deposition using a negative substrate bias voltage is useful for obtaining high-quality dielectric layers.     

Zirconium vacuum arc operation in a mixture of Ar and O2 gases: Ar effect on the arcing characteristics,deposition rate and coating properties

The effect of oxygen and argon partial pressures (P_O2, P_Ar) in a Zr vacuum arc on plasma ion current density J_p, arc voltage V_arc, deposition rate v_d, and selected coating properties was determined. A d.c. arc current of I_arc = 100 A was initiated between a Zr cathode and a grounded anode. Cathode spots produced a plasma jet, which entered a 1/8 torus macroparticle (MP) filter. The plasma was guided by a d.c. magnetic field through an aperture to a glass substrate or a flat disk probe, mounted on a rotatable holder. J_p was measured with the probe, negatively biased to V_b = − 60 V. Coating thickness was measured using a profilometer, and coating properties were investigated using optical microscopy, energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), nano-indentation and optical analysis.     

Combinatorial approach to the growth of α-(Al1 − x,Crx)2O3 solid solution strengthened thin films by reactive r.f. magnetron sputtering

The development of new coatings with superior functionalities for high performance cutting tools is a key challenge in manufacturing. In this context, the synthesis of aluminium oxide and derivative oxide thin films is attracting large scientific and technical interests. The present paper addresses fundamental materials science-based aspects of the physical vapour deposition (PVD) growth of Al-Cr-O thin films at a substrate temperature of 500 °C. A combinatorial experimental approach was chosen to describe the growth and microstructure evolution of Al-Cr-O thin films by means of reactive r.f. magnetron sputtering. A segmented target consisting of two half plates of Al and Cr was used for the deposition carried out under stationary conditions in a laboratory-scale PVD coater. Opposite to the cathode five substrate samples were placed in a line. The r.f. cathode power was set to 500 W and the r.f. substrate bias was set to − 100 V. The total gas pressure was kept constant at 0.4 Pa for all experiments with a fixed ratio of oxygen to argon gas flow. Detailed results on the coatings composition, constitution, microstructure and properties as a function of the elemental composition are presented. X-Ray Diffraction (XRD), X-Ray Reflection (XRR), Transmission Electron Microscopy (TEM) and Electron Probe Microanalysis (EPMA) studies prove the growth of nanocrystalline, stoichiometric, metastable corundum-like solid solution strengthened α-(Al_1 − x,Cr_x)₂O₃ thin films with a high degree of crystallinity, grain sizes between 27 ± 6 nm (in the case of Al-rich coatings) and 44 ± 17 nm (in the case of Cr-rich coatings), Vickers micro hardness values up to 2620 ± 80 HV0.05 and thin film densities between 4.00 g/cm³ (in the case of Al-rich coatings) and 4.86 g/cm³ (in the case of Cr-rich coatings).     

Effect of the aluminium content and the bias voltage on the microstructure formation in Ti1 − xAlxN protective coatings grown by cathodic arc evaporation

The effect of aluminium contents and bias voltage on the microstructure of cathodic arc evaporated Ti_1 − xAl_xN coatings was investigated with the aid of X-ray diffraction experiments and transmission electron microscopy. The coatings were deposited from mixed Ti-Al targets with different Ti:Al ratios (60:40, 50:50, 40:60 and 33:67) at bias voltages ranging between − 20 V and − 120 V. The microstructure of the coatings was described in terms of the phase composition, crystallite size and residual stress and related to the indentation hardness. The microstructure features were found to be related to the uniformity of the local distribution of Ti and Al in (Ti,Al)N, which was controlled, for a certain overall chemical composition of the coatings, by the bias voltage. The consequences of large local fluctuations of the Ti and Al concentrations in Ti_1 − xAl_xN that occurred at higher bias voltages were the phase segregation, which was indicated through the formation of the fcc-(Ti,Al)N/fcc-AlN nanocomposites and the increase of the compressive residual stress in the face-centred cubic (Ti,Al)N. Concurrently, the increasing bias voltage contributed significantly to the reduction of the crystallite size. Higher residual stress and smaller crystallite size increased the hardness of the coatings. The overall chemical composition of the coatings influenced mainly their phase composition. The high concentration of Al in (Ti,Al)N led to the formation of wurtzitic AlN in the coatings.     

Deposition of BN films on metal substrates from a fluorine-containing plasma

Boron nitride (BN) films were deposited on Mo, W, Ni, Ti and Zr substrates by DC arc jet chemical vapor deposition using a gas mixture of Ar-N₂-BF₃-H₂ at 50 Torr, a substrate temperature of 850-1150 °C, and a − 85 V substrate bias. Cubic BN (c-BN) films showing clear c-BN Raman peaks were obtained on Mo and W, but they did not adhere well to the substrates. Hexagonal or turbostratic BN was deposited predominantly on Ni substrates, which is similar to the preferable deposition of graphitic carbons in diamond CVD. High quality c-BN films with good adhesion were obtained on Ti and Zr. The reasons for these differences among metal substrates are discussed.     

高功率脉冲和脉冲直流磁控共溅射CrAlN薄膜的研究

目的通过掺杂适量Al元素来固溶强化Cr N薄膜,从而提高薄膜的抗氧化性能和热稳定性。方法采用高功率脉冲磁控溅射和脉冲直流磁控溅射复合镀膜技术制备了Cr Al N薄膜,利用XRD、纳米压痕仪、应力仪、摩擦磨损试验机系统地研究了不同基体偏压对CrAlN涂层结构和力学性能的影响。结果所有CrAlN涂层均以fcc-(Cr,Al)N相为主,且随着基体偏压的增加,沿(111)晶面生长的衍射峰逐渐减弱,并向小角度偏移;薄膜压应力显著增加,最大值为-2.68GPa;薄膜硬度先上升后下降,在基体偏压为-30V时,硬度达到最大值22.3 GPa;H/E值和H~3/E~(*2)值随着基体偏压的增加,近似线性增大,当偏压为-120 V时,均达最大值0.11、0.21 GPa,同时摩擦系数和磨损率逐渐减小。结论当基体偏压为-120 V时,CrAlN薄膜具有最佳的耐磨性能,H/E和H~3/E~(*2)在一定程度上可评价涂层的耐磨性。     

Constitution, microstructure, and battery performance of magnetron sputtered Li-Co-O thin film cathodes for lithium-ion batteries as a function of the working gas pressure

Li-Co-O thin film cathodes have been deposited onto Si and stainless steel substrates by RF magnetron sputtering from a ceramic LiCoO₂ target at various working gas pressures from 0.15 to 25 Pa. Composition, crystal structure and thin film morphology were examined and properties such as intrinsic stress, conductivity and film density were determined. As-deposited films at 0.15 Pa as well as in the range between 5 Pa and 10 Pa working gas pressure showed a nanocrystalline metastable rocksalt structure with disordered cation arrangement and were nearly stoichiometric. To induce a cation ordering the films were annealed in a furnace at temperatures between 100 and 600 °C for 3 h in argon/oxygen atmosphere (Ar:O₂ = 4.5:5) of 10 Pa. This cation ordering process was observed by XRD and Raman spectroscopy. For the films deposited at 10 Pa gas pressure an annealing temperature of 600 °C leads to the formation of the high temperature phase HT-LiCoO₂ with a layered structure. The Raman spectrum of the films deposited at 0.15 Pa and annealed at 400 °C indicates the formation of the low temperature phase LT-LiCoO₂ with a cubic spinel-related structure, which is assumed to be stabilized due to high compressive stress in the film. The electrochemical characterisation of annealed thin film cathodes revealed that the discharge capacity strongly depends on the crystal structure. Thin Li-Co-O films with a perfect layered HT-LiCoO₂ structure showed the highest discharge capacities.