Hardness of nanocomposite a-C:Si films deposited by magnetron sputtering

Hydrogen-free a-C:Si films with Si concentration from 3 to 70 at.% were prepared by magnetron co-sputtering of pure graphite and silicon at room temperature. Mechanical properties (hardness, intrinsic stress), film composition (EPMA and XPS) and film structure (electron diffraction, Raman spectra) were investigated in dependence on Si concentration, substrate bias and deposition temperature. The film hardness was maximal for ∼ 45 at.% of Si and deposition temperatures 600 and 800 °C. Reflection electron diffraction indicated an amorphous structure of all the films. Raman spectra showed that the films in the range of 35–70 at.% of Si always contain three bands corresponding to the Si, SiC and C clusters. Photoelectron spectra showed dependency of Si–C bond formation on preparation conditions. In the films close to the stoichiometric SiC composition, the surface and sub-surface carbon atoms exhibited dominantly sp³ bonds. Thus, the maximal hardness was observed in nanocomposite a-C:Si films with a small excess of carbon atoms.     

Structural and photoelectrochemical properties of SrTaO2N oxynitride thin films deposited by reactive magnetron sputtering

In this study, the influence of the degree of crystallization and thickness of films was correlated with the photoelectrochemical performance of SrTaO₂N semiconductor films for O₂ evolution reaction under visible light irradiation. Oxynitride films were deposited on various substrates using the sputtering in Ar + N₂ reactive atmosphere from a home-made SrTaO₂N target. Films with stoichiometric composition were obtained at a high temperature (T_S =800 °C) with reduced bandgap. The different substrates led to diverse degrees of film crystallization, from weakly crystallized to fully c-axis oriented. The photoelectrochemical performance was improved by improving the film crystallinity and the thickness. For further improvement of the photoelectrochemical performance, the following three limiting factors are identified: 1) low absorption coefficient, especially in the visible domain from 500 to 600 nm; 2) short lifetimes of excited charge carriers; and 3) permittivity with only moderate values lower than 10 in the visible-light domain.     

Dielectric properties of amorphous BaTiO3 films deposited by RF magnetron sputtering

In the present paper, dielectric properties of a-BaTiO₃ films have been investigated as a function of frequency (10⁻¹ to 10⁵ Hz) and temperature (25–350 °C) using the dielectric spectroscopy technique. Relaxation and ac-conductivity processes were analyzed in order to study charge transport in the bulk and at the electrode-film interfaces. It seems that the oxygen vacancies play an essential role in both processes.     

Structural and optical properties of ZnS thin films deposited by RF magnetron sputtering

Zinc sulfide [ZnS] thin films were deposited on glass substrates using radio frequency magnetron sputtering. The substrate temperature was varied in the range of 100°C to 400°C. The structural and optical properties of ZnS thin films were characterized with X-ray diffraction [XRD], field emission scanning electron microscopy [FESEM], energy dispersive analysis of X-rays and UV-visible transmission spectra. The XRD analyses indicate that ZnS films have zinc blende structures with (111) preferential orientation, whereas the diffraction patterns sharpen with the increase in substrate temperatures. The FESEM data also reveal that the films have nano-size grains with a grain size of approximately 69 nm. The films grown at 350°C exhibit a relatively high transmittance of 80% in the visible region, with an energy band gap of 3.79 eV. These results show that ZnS films are suitable for use as the buffer layer of the Cu(In, Ga)Se₂ solar cells.     

Corrosion performance of thin hydrogenated amorphous carbon films prepared by magnetron sputtering

Hydrogenated amorphous carbon (a-CH_x) films were prepared by magnetron sputtering at different H₂/Ar gas flow ratios. Several sets of perpendicular magnetic recording disks with a-CH_x overcoats of 5 nm were prepared for accelerated environmental corrosion test. The corrosion spots on the disks and the corrosion products were analyzed using optical surface analyzer and time-of-flight secondary ion mass spectroscopy, respectively. Other techniques, such as Raman spectroscopy, atomic force microscopy nano-scratch and contact angle measurement, were used to characterize the properties of a-CH_x films. Compared to pure carbon overcoat, all the a-CHx overcoats have better corrosion resistance and higher polar component of surface free energy. The a-CH_x film with appropriate H content shows the highest scratching resistance, and the corresponding disk has the lowest corrosion area on the disk surface after the accelerated corrosion.     

Atomic force microscopy investigation of the effects of annealing on amorphous carbon nitride films deposited by r.f. magnetron sputtering

Atomic force microscopy is used to study the effects of thermal annealing on the surface topography and the tribological properties of amorphous carbon nitride thin films deposited by r.f. magnetron sputtering. The results show that the surface roughness decreases with increasing annealing temperature. The friction coefficients at the interface between a Si₃N₄ tip and the amorphous carbon nitride films surface decrease with increasing smoothness of the surface.     

Effect of deposition parameters on properties of TiO2 films deposited by reactive magnetron sputtering

TiO₂ films were grown onto unheated 5083 aluminum alloy substrates by reactive magnetron sputtering from a pure Ti target in Ar-O₂ gas mixture in different power, bias voltage, Ar/O₂ ratio and deposition time at room temperature. The effects of different deposition parameters on the structure and properties of TiO₂ films were investigated systematically by field emission scanning electron microscope (FESEM), atomic force microscope (AFM), X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), nanoindentation tests, electrochemical tests and antibacterial tests. The results show that power and bias voltage are two main factors to affect the structure and properties of TiO₂ films during the sputtering process. XRD results show that anatase phase is the main phase of the film, and the enhanced content of anatase phase with the increase of sputtering power and bias voltage. Nanoindentation tests exhibit that higher H/E (Hardness/Modulus) ratio can be achieved by depositing TiO₂ film. And the corrosion resistance and antifouling property are all improved after depositing TiO₂ film. 2# sample shows the optimal corrosion resistance, E_corr and I_corr are −0.27388 V and 3.7232 μA/cm², respectively. 1# sample exhibits excellent antibacterial property, the d ensity of bacteria is only 217 cell / mm², which is 484% higher than that of uncoated matrix.     

Sulphur doped DLC films deposited by DC magnetron sputtering

Diamond‐like carbon (DLC) and sulphur doped diamond‐like carbon (S‐DLC) films were synthesised at different sulphur molar percentage of 0%, 2%, 5%, 8% and 10% by direct current (DC) magnetron sputtering process using novel compressed sulphur‐graphite targets at relatively low power density. Films were characterised for their morphologies, structural, electrical and optical properties. Scanning electron microscope images reveal changes in the quality of the obtained films shown by the denser packing of DLC grains at different sulphur percentage. The conductivities of S‐DLC films were found to be in the range of 6.0 × 10^?3–0.6/Ω cm. The optical band gap energies were found to be in the range of ～1.4–2.0 eV. Both electrical and optical measurements exhibit nonlinear responses with optimum at around 5% sulphur molar percentage (minimum for conductivity and maximum for optical band gap energy). These trends of change in both conductivity and optical band gap energy are consistent with the variation in bond characters of the films indicated by Raman spectroscopy. © 2011 Canadian Society for Chemical Engineering     

Enhanced photocatalytic activity of TiO2-ZnO thin films deposited by dc reactive magnetron sputtering

The effect of deposition conditions on the photocatalytic activity of TiO₂-ZnO thin films was studied. By using a (Ti)₉₀-(Zn)₁₀ alloy target, the samples were deposited at room temperature on glass substrates by dc reactive magnetron sputtering and post-annealed in air at 500 °C. The dependence of the physical properties of the films on the O₂/Ar gas ratio and the deposition working pressure was investigated. XRD patterns showed mainly the formation of the anatase phase of TiO₂. Optical absorption measurements exhibited a blue shift of the band-gap energy with increasing working pressure. XPS spectra indicated the presence of the Ti⁴⁺ and Zn²⁺ oxidation states, which correspond to TiO₂ and ZnO, respectively. The chemical state of Ti was further analyzed by means of the modified Auger parameter, α’, which gave a value of ca. 873 eV. The photocatalytic property of the films was assessed by the degradation of a methylene blue aqueous solution. The maximum photocatalytic performance was observed for the samples deposited at 3.0 mTorr and O₂/Ar gas ratio of 10/90. These results are explained in terms of the structural, optical, and morphological properties of the films.     

Adhesion and fatigue resistance of Ta-doped MoS2 composite coatings deposited with pulsed-DC magnetron sputtering

MoS₂–Ta composite coatings were deposited using the pulsed-DC magnetron sputtering technique. X-ray diffraction (XRD), scanning electron microscopy, energy dispersive spectroscopy, and atomic force microscopy were used to determine the structural properties of the MoS₂–Ta composite coatings. The hardness values and adhesion and fatigue features of the coatings were determined using a microindentation hardness test and a scratch test, respectively. The scratch tests were evaluated using two modes: a standard mode (under a progressive load) and a multimode (sliding-fatigue with a constant sub-critical load within the same scratch track). Failure mechanisms of the scratch tracks were determined by examining the resulting micrographs. The MoS₂–Ta coatings have a dense columnar microstructure. XRD patterns of the coatings revealed MoS₂ (0?0?2), MoS₂ (1?0?0), MoS₂ (1?0?3), and α-Ta (1?1?0) reflections. The thickness, roughness, hardness, and elemental ratio values of the coatings were significantly affected by the target currents. The adhesion of the coatings dramatically increased with an increase in the thickness, hardness, and Ta/Mo ratio and with decreases in the roughness. The MoS₂–Ta composite coatings with a high load-bearing capacity exhibited excellent fatigue resistance.     

Structural and nanomechanical properties of BiFeO3 thin films deposited by radio frequency magnetron sputtering

The nanomechanical properties of BiFeO₃ (BFO) thin films are subjected to nanoindentation evaluation. BFO thin films are grown on the Pt/Ti/SiO₂/Si substrates by using radio frequency magnetron sputtering with various deposition temperatures. The structure was analyzed by X-ray diffraction, and the results confirmed the presence of BFO phases. Atomic force microscopy revealed that the average film surface roughness increased with increasing of the deposition temperature. A Berkovich nanoindenter operated with the continuous contact stiffness measurement option indicated that the hardness decreases from 10.6 to 6.8 GPa for films deposited at 350°C and 450°C, respectively. In contrast, Young''s modulus for the former is 170.8 GPa as compared to a value of 131.4 GPa for the latter. The relationship between the hardness and film grain size appears to follow closely with the Hall–Petch equation.     

Effect of the substrate temperature on the physical characteristics of amorphous carbon films deposited by d.c. magnetron sputtering

The growth rate, composition, electrical resistivity, mass density, refractive index and microstructure of amorphous carbon (a-C) films prepared by direct current (d.c.) magnetron sputtering were investigated as functions of the substrate temperature (50–350°C). The hydrogen content determined by elastic recoil detection analysis (ERDA) and the electrical resistivity of films were found to be dependent on both the base pressure in the deposition chamber and substrate temperature. For films deposited below 200°C, the hydrogen content was less than 2 at.% and the substrate temperature was the only parameter which affected their electrical resistivity. The electrical resistivity decreased from 0.2 to 0.03 Ωcm as the substrate temperature increased from 50 to 200°C. The mass density of films evaluated from Rutherford backscattering (RBS) data and film thickness decreased from 2.2 to 1.4 g cm⁻³ with increasing substrate temperature. A linear relationship between the refractive index and the mass density of a-C films was clearly established. From the optical measurements, the decrease in mass density was correlated to an increase in porosity of films with increasing substrate temperature. The decrease in electrical resistivity with increasing substrate temperature was attributed to a graphitization of a-C films. This modification of the microstructure of a-C films as the deposition temperature was varied from 50 to 350°C was observed by examination of the cross-section of samples by transmission electron microscopy and Raman spectroscopic analyses of a-C films.     

Advanced TiC/a-C:H nanocomposite coatings deposited by magnetron sputtering

TiC/a-C:H nanocomposite coatings have been deposited by magnetron sputtering. They consist of 2–5 nm TiC nanocrystallites embedded in the amorphous hydrocarbon (a-C:H) matrix. A transition from a columnar to a glassy microstructure has been observed in the nanocomposite coatings with increasing substrate bias or carbon content. Micro-cracks induced by nanoindentation or wear tests readily propagate through the column boundaries whereas the coatings without a columnar microstructure exhibit substantial toughness. The nanocomposite coatings exhibit hardness of 5–20 GPa, superior wear resistance and strong self-lubrication effects with a friction coefficient of 0.05 in air and 0.01 in nitrogen, under dry sliding against uncoated bearing steel balls. Especially, reversible transitions from low to ultra-low friction are observed if the atmosphere is cycled between ambient air and nitrogen. The lowest wear rate is obtained at high humidity.     

An investigation of the work function and stability of chromium oxide thin films deposited by reactive magnetron sputtering

Journal of Applied Electrochemistry - The deposition parameters used during the sputtering process are instrumental in determining the properties of the deposited films and can be optimised to...     

Study of the thermal stability of carbon nitride thin films prepared by reactive magnetron sputtering

CN_x amorphous films have been prepared by reactive magnetron sputtering in a pure N₂ discharge. The films grown on NaCl have been characterised by Fourier transform infrared spectroscopy (IR), transmission electron microscopy (TEM), and electron energy loss spectroscopy (EELS). C/N atomic ratios have been determined by EELS with values in the range 2.0–1.2 for samples grown under different conditions. The thermal stability of the films upon heating in vacuum was followed ‘in situ’ at the transmission electron microscope by EELS. This study has been completed by a thermogravimetric and mass spectrometer analysis of evolved gases upon heating in nitrogen flow and vacuum, respectively. Under these conditions the films are stable up to 1023 K. Above this temperature the films decompose by elimination of nitrogen remaining a carbonaceous residue. The thermal stability of the films upon annealing in air was studied by following the evolution of the X-ray photoelectron spectroscopy (XPS) peaks during heating in air of films grown on steel. Deconvolution analysis of the XPS spectra allows to determine the evolution of the different type of bonds. In particular pure carbon in the films appears more reactive to oxygen than CN and C–N bonds.     

Zinc oxide films deposited by radio frequency plasma magnetron sputtering technique

Zinc oxide (ZnO) is a wide band gap transparent conductive oxide (TCO) material with a lot of potential applications including transparent thin-film sensors, transistors (TFTs), solar cells, and window insulation systems. In this work, ZnO films were deposited on glass substrates by the radio frequency (RF) plasma magnetron sputtering deposition technique. The effects of the RF power on the properties of the ZnO films were elucidated. The influences of the RF power on the surface morphology, structural, and optical properties of the ZnO films were investigated by Mahr surface profilometer, Atomic Force Microscopy (AFM), X-ray diffractometer (XRD), and ultraviolet–visible (UV–VIS) spectrophotometer. To allow for accurate comparison of the power effects, ZnO films with similar thickness deposited at different RF powers were examined. The RF power effects on the properties of the ZnO films are revealed and discussed in this paper.     

Growth evolution of CaB6 thin films deposited by DC magnetron sputtering

CaB₆ films were deposited by a DC magnetron sputtering method to explore the growth evolution systematically through changing sputtering time. The crystalline structure was characterized by XRD and GIXRD respectively, which showed that the films were anisotropic with nanocrystalline structure. The grain sizes increased with the deposition time, and a weak (100) texture appeared when the deposition time reached to 120 min. HRTEM was employed to demonstrate the crystalline structure. The surface morphology evolution of CaB₆ films was analyzed by AFM and FESEM. The results showed that the films were initially formed by fine columnar grains. With the deposition time extended, the films exhibited a dense columnar structure with faceted surfaces. The grain size, film thickness and crystallization degree all increased with the sputtering time.     

Mechanical and tribological properties of boron,nitrogen-coincorporated diamond-like carbon films prepared by reactive radio-frequency magnetron sputtering

We have deposited boron- and/or nitrogen-incorporated DLC films by radio-frequency magnetron sputtering, and systematically investigated the structure and the mechanical and tribological properties. The N content in DLC films increased with increasing N₂ flow ratio [N₂/(Ar + N₂)], and it tended to be saturated at higher N₂ flow ratios. The N content further increased with an increase in the B content of the targets. The B/C ratios of the films were almost the same as those of the B-containing targets regardless of the N content. Scratch tests revealed that the adhesion strength of N-incorporated DLC films decreased with increasing N₂ flow ratio and the critical loads of B-incorporated films were lower than that of an unincorporated film. It was found that for B, N-coincorporated films there was an optimum N₂ flow ratio at which the critical load became a maximum value, which was higher than that of the unincorporated film. The optimum N₂ flow ratio increased with an increase in the B composition of the targets. The N-incorporated films peeled off during ball-on-plate friction tests. On the other hand, the B, N-coincorporated films showed good wear-resistant properties that the specific wear rates were lower than those of the unincorporated and B-incorporated films.     

磁控溅射制备非晶态WO_3薄膜的光催化性能

采用射频反应磁控溅射工艺在玻璃基片上沉积了非晶态WO3薄膜。通过光催化降解亚甲基蓝和罗丹明B溶液实验,研究了所制WO3薄膜的光催化活性和使用寿命。X射线衍射(XRD)分析表明:所制备的WO3薄膜为非晶态。光催化实验表明:紫外光照3h后,薄膜对亚甲基蓝和罗丹明B溶液的最大降解率分别为83.26%和72.73%。重复使用3次后,薄膜对亚甲基蓝的降解率保持在75%以上,7次使用后薄膜基本丧失光催化活性。采用去离子水超声处理30min的方法可使已失活薄膜对亚甲基蓝的降解率从20%恢复至81%。