DC Reactive Magnetron Sputtering Process Research Articles

Oxygen plasma treatment WO3 nanorods for Improvement H2S gas sensing

Herein, the oxygen (O2) plasma has been used to post-treat tungsten oxide (WO3) nanorods to improve the sensing performance of the H2S gas sensor. The reactive DC magnetron sputtering process with the glancing-angle deposition (GLAD) technique was used to prepare the WO3 nanorods. After deposition, the WO3 nanorod thin films were treated with O2 plasma at different treatment power from 100 – 200 W. The physical structure of as-deposition and treated WO3 nanorod thin films was investigated crystal structure and morphology by grazing incident X-ray diffraction (GIXRD), field-emission scanning electron microscope (FE-SEM), and high-resolution transmission electron microscope (HRTEM). The result indicated that the WO3 nanorod structure transformed to the monoclinic polycrystalline phase. FE-SEM and HRTEM observed slight changes in the shape of the WO3 nanorods. The H2S sensing properties were measured at 10 ppm at 150 – 350°C operating temperatures. At an operating temperature of 200 °C, the response to H2S of O2 plasma treated WO3 nanorods is increased by a factor of 5 – 15, and the maximum response to H2S is 15. The results showed that the O2 plasma treatment process improved the sensing response of the WO3 nanorods.

In-situ hydrogenated V2O5 thin films: Study of the structural dynamics and their behavior as Li-ion batteries cathode

This investigation focuses on a one-step preparation method to produce hydrogenated V2O5 thin films by controlling the atmosphere of the DC reactive magnetron sputtering process. An increasing hydrogen flux during the film deposition promotes the formation of defects such as oxygen vacancies and hydroxyl sites in the oxide matrix. The hydrogenated samples were tested as cathodes in Li-ion batteries and exhibited lower charge capacities but superior stability to cycling compared to pristine V2O5 film. These results pave the way to prepare hydrogenated transition metal oxide thin films by a simple route without further thermal procedures and affordable conditions.

Tweaking the mechanical stability of Al1−xWxN ternary nitride alloys for hard coating applications, and study on their structural, photoluminescence and surface chemical analysis

This study focuses on the synthesis and achievement of ternary Al1−xWxN nitride films as hard coating materials. A dual-target DC reactive magnetron sputtering process was used to coat Al1−xWxN thin films on Si (100), glass, and transparent quartz substrates. The elemental analysis of the films was calculated by energy dispersion spectroscopy and the corresponding value of x changes from 0 to 1. The X-ray diffraction data showed a-axis orientation of the AlN films with hexagonal phase and amorphous nature for Al0.78W0.22N and Al0.58W0.42N films. Atomic force microscopy analysis showed that the surface morphology of Al0.78W0.22N films was better than that of AlN and Al0.3W0.7N films, as evidenced by the significantly lower root-mean-square roughness value of 1.79 nm compared to 5.78 and 13.9 nm, respectively. The resistivity of Al1−xWxN films was determined by a four-probe method and resulted in a record low value of 4.08 × 10−5 Ω-m for WN films. The photoluminescence emission spectra showed distinct peaks in the visible region at different wavelengths, and the deconvoluted blue emission peak was attributed to the native defects in the Al1−xWxN films. X-ray absorption spectroscopy data showed an increase in feature-a from Al0.78W0.22N to Al0.58W0.42N films, indicating stronger hybridization of N 2p with Al 3p and W 5d orbitals due to π * -resonance. The oxygen content calculated by X-ray photoelectron spectroscopy was 34.6, 35.39, and 19.74 at% on the surface of AlN, Al0.58W0.42N, and WN films, respectively. The surface oxidation of AlN films triggered the transfer of charge from nitrogen to oxygen on the surface of AlN films. The nanoindentation results showed that the Al0.3W0.7N films have hardness and elastic modulus of 17.84 GPa and 196.96 GPa, which are higher than those of the other Al1−xWxN films, while the AlN films have higher fracture toughness due to the reduction of contact pressure.

Growth of Highly c-Axis Oriented AlScN Films on Commercial Substrates.

In this work, we present a method for growing highly c-axis oriented aluminum scandium nitride (AlScN) thin films on (100) silicon (Si), silicon dioxide (SiO2) and epitaxial polysilicon (poly-Si) substrates using a substrate independent approach. The presented method offers great advantages in applications such as piezoelectric thin-film-based surface acoustic wave devices where a metallic seed layer cannot be used. The approach relies on a thin AlN layer to establish a wurtzite nucleation layer for the growth of w-AlScN films. Both AlScN thin film and seed layer AlN are prepared by DC reactive magnetron sputtering process where a Sc concentration of 27% is used throughout this study. The crystal quality of (0002) orientation of Al0.73Sc0.27N films on all three substrates is significantly improved by introducing a 20 nm AlN seed layer. Although AlN has a smaller capacitance than AlScN, limiting the charge stored on the electrode plates, the combined piezoelectric coefficient d33,f with 500 nm AlScN is only slightly reduced by about 4.5% in the presence of the seed layer.

Interface-driven magnetic anisotropy of epitaxial [formula omitted] thin films

The effect of film-substrate interface on the magnetic anisotropy (MA) of epitaxial Fe4N thin films grown on single crystalline MgO (100) and MgO (111) substrates has been studied in this work. Both samples were grown simultaneously using a reactive dc magnetron sputtering process at a substrate temperature of 250°C. Single phase Fe4N samples were found to grow epitaxially on (100) and (111) oriented MgO substrates as confirmed from out-of-plane x-ray diffraction and in-plane ϕ-scan measurements. The MA of (100) and (111) oriented Fe4N samples was measured using longitudinal magneto-optical Kerr effect (MOKE). In spite of being grown simultaneously, the MA of both these samples was found to be different. Secondary ion mass spectroscopy and x-ray reflectivity measurements revealed the formation of a dense layer at the film-substrate interface. The MA of this dense layer along with the MA of Fe4N has a dramatic effect on magnetic reversal depending on the orientation of the substrate. Further, from the MOKE measurements, the difference in the magnetization switching processes was found to depend on the microstructure and orientation of Fe4N thin films.

Oxygen effect on structural and optical properties of zinc oxide

ABSTRACTThis article deals with an investigation of the effect of oxygen content on optical and structural properties of ZnO films. Zinc oxide films were deposited with the DC reactive magnetron sputtering process on Si(100) and glass substrates. ZnO films were elaborated at different oxygen flow rates from (O2) 12 to 35 sccm. The evolution of optical and structural properties as a function of O2 was investigated by X-ray diffraction, Profilometer, Field Emission Scanning Electron Microscopy (FESEM) and ultraviolet–visible. By increasing O2, the crystallite size increases from 20 to 27 nm, which leads to an enlargement in the ZnO band gap from 3.18 to 3.30 eV. At 30 sccm of O2, the films present a significant improvement in the band gap (3.30 eV). The results reveal that with increasing O2, all films show a high crystallinity in the wurtzite phase and present a (002)ZnO preferential orientation along the c-axis. ZnO exhibited a good self-texture.

Bio-tribocorrosion behavior of a nanocrystalline TiZrN coating on biomedical titanium alloy

A nanocrystalline TiZrN graded coating was deposited on biomedical titanium alloy by DC reactive magnetron sputtering process. The microstructure and compositions of the coating were characterized by XRD, TEM and EPMA. The electrochemical corrosion and bio-tribocorrosion behavior of the coated titanium alloy under open circuit potential (OCP) and applied potentials (−0.15 V ~ +0.25 V) were investigated in Hank's solution with and without 25% calf serum. Compared with TiN coating, the hardness of TiZrN coating is greatly increased due to the Zr solid solution strengthening and nanocrystalline strengthening. Under the conditions of OCP and applied anodic potentials, the TiZrN coated Ti alloy exhibits significantly improved anti-tribocorrosion and anti-friction performances, which are attributed to that the stable Ti and Zr oxide or oxynitride passive film on coating near surface and the increased mechanical properties of the coating decrease the synergistic effect of corrosion and wear. 25% calf serum in Hank's solution enhances the chemical stability of the TiZrN coating through adsorption and bio-lubrication mechanism, and therefore further improves the tribocorrosion performance of the coated Ti alloy.

Performance analysis and comparative assessment of nano-composite TiAlSiN/TiSiN/TiAlN coating in hard turning of AISI 52100 steel

The present study investigates the machining performance of coatings deposited by cathode arc evaporation (CAE) and DC reactive magnetron sputtering (DCRMS) process with different structures and deposition layers on Al2O3/TiCN ceramic inserts in turning of hardened steel under dry cutting environment. Mono-layered AlCrN and multi-layered AlTiN were deposited using CAE process whereas nano-structured TiAlSiN/TiSiN/TiAlN coating was deposited using DCRMS process. The coated tools resulted in improved machining performance when compared to uncoated cutting tool. The CAE process resulted in surface defects like droplets and pores whereas the sputtering process generated droplet free surface that helped in superior performance of TiAlSiN/TiSiN/TiAlN coating when compared with AlTiN and AlCrN coatings. Moreover, nanostructure in TiAlSiN/TiSiN/TiAlN coating prevented coating flaking or peeling and ensured superior anti-abrasive behaviour due to its amorphous structure.

Structure and magnetization of [formula omitted] thin film

In this work, we studied the local structure and the magnetization of Co4N thin films deposited by a reactive dc magnetron sputtering process. The interstitial incorporation of N atoms in a fcc Co lattice is expected to expand the structure. This expansion yields interesting magnetic properties e.g. a larger magnetic moment (than Co) and a very high value of spin polarization ratio in Co4N. By optimizing the growth conditions, we prepared Co4N film having lattice parameter close to its theoretically predicted value. The N concentration was measured using secondary ion mass spectroscopy. Detailed magnetization measurements using bulk magnetization method and polarized neutron reflectivity confirm that the magnetic moment of Co in Co4N is higher than that of Co.

Rare earth Ce-modified (Ti,Ce)/a-C:H carbon-based film on WC cemented carbide substrate**Project supported by the National Natural Science Foundation of China (Grant Nos. 51302116 and 51365016) and the Program for Excellent Young Talents, Jiangxi University of Science and Technology, China.

WC cemented carbide suffers severe wear in water environments. A novel carbon-based film could be a feasible way to overcome this drawback. In this study, a rare earth Ce-modified (Ti,Ce)/a-C:H carbon-based film is successfully prepared on WC cemented carbide using a DC reactive magnetron sputtering process. The microstructure, mechanical properties, and tribological behavior of the as-prepared carbon-based film are systematically investigated. The results show that the doping Ti forms TiC nanocrystallites that are uniformly dispersed in the amorphous carbon matrix, whereas the doping Ce forms CeO2 that exists with the amorphous phase in the co-doped (Ti,Ce)/a-C:H carbon-based film. The mechanical properties of this (Ti,Ce)/a-C:H film exhibit remarkable improvements, which could suggest higher hardness and elastic modulus as well as better adhesive strength compared to solitary Ti-doped Ti/a-C:H film. In particular, the as-prepared (Ti,Ce)/a-C:H film presents a relatively low friction coefficient and wear rate in both ambient air and deionized water, indicating that (Ti,Ce)/a-C:H film could feasibly improve the tribological performance of WC cemented carbide in a water environment.

Effect of structural defects on corrosion initiation of TiN nanocrystalline films

TiN thin films were deposited on AISI304 stainless steel using a DC reactive magnetron sputtering process. An in situ observation is carried out in order to investigate the relationship between the corrosion initiation and the structural defects such as pores and pinholes by using atomic force microscopy (AFM). It is found that the corrosion initiates at some larger structural pores in the form of the detachment of the particles which will plug the transport path for the corrosion products, whereas the small enough pinholes are easily filled in by corrosion products at the beginning of corrosion. Also, the surface roughness of the corroded film is improved with increasing the corrosion time. The corrosion morphology after polarization test shows that fewer and large pits appear on the TiN-coated substrates probably associated with large structural defects such as high density area of through film pores or pinholes present in the films, which is in accord with those results obtained by in situ AFM observation. Additionally, the effect of bias voltages on corrosion resistance of the films is also involved because the structural defects are strongly associated with the bias voltages.

Sputtering-Pressure Dependent Optical and Microstructural Properties Variations in DC Reactive Magnetron Sputtered Titanium Nitride Thin Films

Titanium nitride thin films were prepared using DC reactive magnetron sputtering process in a 99.998% reactive nitrogen atmosphere. The sputtering pressure was varied to study its influence on the as-deposited films, using low (0.80 Pa), intermediate (3.40-5.33 Pa) and high (11.33 Pa) sputtering pressures. The deposited films possessed colour that ranged from dark blue, characteristic of oxygen-rich titanium nitride films, to reflective golden yellow, reminiscent of stoichiometric TiNx films. Studies on the optical and microstructural properties were carried out using UV-visible spectrophotometry, scanning electron microscopy (SEM) and X-ray diffractometry. Characterization results showed variation in the optical and structural properties of the film depending on the deposition sputtering pressure with relatively higher enhancement in the optical transmittance of up to 97.52% in the visible region for films deposited under high and intermediate sputtering pressure conditions. The deposition rate of the films was found to decrease with sputtering pressure. In the same vein, the optical transmittance of the films reduced from 97.52 to 10.05% and the transmission band shifted towards higher wavelength with the decrease of the sputtering pressure.

Influence of Substrate Temperature on the Properties of Al-Doped Zinc Oxide Films Prepared by DC Reactive Magnetron Sputtering

Transparent and conductive c-axis oriented aluminum-doped zinc oxide (AZO) films have been prepared on glass substrate by dc reactive magnetron sputtering process. The structural, optical and electrical properties of the films were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), UV-Visible spectrophotometer and Hall effect measurement system. As the substrate temperature increased, the results showed that grain size of the AZO films gradually increased, the films had a strong c-axis oriented and the crystallization of films became better. The absorption edge first shows a red shift, and then switches to the blue shift with increasing substrate temperature. Optical band gap of AZO films first decreases and then increases with increasing substrate temperature. Resistivity of AZO films decreases with increasing substrate temperature but the rate of decline of resistivity becomes slow after substrate temperature reaches 250 °C. The carriers concentration of AZO films increases with substrate temperature increase.

Technological Parameters and Electrical Properties of Ti/TiN Multilayer Films Prepared by Magnetron Sputtering

A series of Ti/TiN multilayer films was deposited on Si substrates by DC reactive magnetron sputtering process. The influence of sputtering current density and substrate temperature on cycle membrane structure and its electrical properties was investigated in this study. The results show that: when the current density is 0.4A, the sheet resistance and electrical resistivity of the film are of the minimum value. The sheet resistance and electrical resistivity of the film decrease with an increase of substrate temperature. Therefore, sputtering current density should be controlled between 0.3-0.4A, while the substrate temperature should be above 400°C. For a given modulation period and modulation ratio, with the change of number of cycles the films can present a unique set of colours, and its electrical resistivity decreases with an increase in the number of cycles. When the number of cycles is greater than 4, the sheet resistance is significantly reduced, and when the number is greater than 15, the prepared films come off. To keep the number of cycles at five and change the modulation period, it is shown that a minimum electrical resistivity exists.

Tribological properties of Cr–Si–N nanocomposite film adherent silicon under various environments

Chromium nitride thin films have good corrosion resistance and mechanical properties. However, their hardness is slightly lower than that of other hard coatings. The concept of nanocomposite thin films is employed by adding silicon to form Cr–Si–N thin films with enhanced hardness and wear resistance. In this study, Cr–Si–N films with various Si contents were coated on silicon wafer to enhance the tribological properties and anticorrosion by a bipolar symmetry pulsed DC reactive magnetron sputtering process. The tribological properties were studied by a pin-on-disk tester. The tests were conducted with the same operating condition under three different environments. They were performed in the ambient atmosphere (in 55% humid air), DI water, and 0.01 M NaCl aqueous solution, respectively. The wear tests revealed that, as the silicon content was increased, even though the Cr–Si–N films had a better anticorrosion property they had an inferior performance on wear resistance. The results were concluded to be mainly due to Cr–Si–N films’ microstructures and adhesion to the Si substrate rather than their hardness and toughness.

Characteristics of N-doped TiO 2 thin films grown on unheated glass substrate by inductively coupled plasma assisted dc reactive magnetron sputtering

N-doped TiO 2 thin films have been deposited on unheated glass substrates by an inductively coupled plasma (ICP) assisted direct current (dc) reactive magnetron sputtering. All films were produced in the metallic mode of sputtering in order to achieve a high deposition rate. The structures and properties of the N-doped TiO 2 films were studied by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, field emission scanning electron microscopy and UV–Vis spectrophotometer. Experimental results show that we can obtain well crystallized N-doped anatase phase TiO 2 thin films at low deposition temperature and at high deposition rate by using the ICP assisted dc reactive magnetron sputtering process. The doping of nitrogen into TiO 2 lattices leads to a smooth shift of the absorption band toward visible light regions.

Microstructure and mechanical properties of pulsed DC magnetron sputtered nanocomposite Cr–Cu–N thin films

The nanocomposite Cr–Cu–N thin films have been deposited at a substrate temperature of 250 °C by a bipolar asymmetric pulsed DC reactive magnetron sputtering process. Different Cu contents ranging from 0.4 to 14.9 at.% were achieved. The structures of Cr–Cu–N thin films were analyzed by XRD. The surface and cross sectional morphologies of thin films were examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The nanoindentation and scratch tests were adopted to evaluate the mechanical and tribological properties of Cr–Cu–N coatings. The influences of Cu content on the structure, mechanical and tribological properties of Cr–Cu–N coatings were explored. It is observed that the columnar structure no longer exists when the Cu content exceeds 10.9 at.%. The stability of CrN phase in the coating is influenced by the Cu content. The scratching coefficient of thin films decreases with increasing Cu content. Sufficient adhesion and tribological properties of Cr–Cu–N coatings are achieved. The maximum average hardness around 20 GPa and scratching coefficient around 0.1 are found in the coatings with around 2.1 to 2.6 at.% Cu in this work.

The mechanical properties evaluation of the CrN coatings deposited by the pulsed DC reactive magnetron sputtering

The chromium nitride coatings have been deposited by the bipolar symmetric pulsed DC reactive magnetron sputtering process at different temperature and pulse substrate bias. The pulse frequencies of target power and the substrate bias were kept at 2 kHz and 50 kHz, respectively. The nanoindenter, scratch and Daimler-Benz Rockwell-C adhesion tests were adopted to evaluate the mechanical properties of the CrN coatings. The preferred orientation of the CrN coatings changed from (111) to (200) with increasing substrate temperature and negative bias voltage applied. The hardness and adhesion properties of the coatings also increased with substrate temperature and a − 290 V bias voltage. A CrN film with 21 GPa in hardness and good adhesion property was deposited at 300 °C and − 290 V bias. It is observed that through the bipolar symmetry pulsed DC reactive magnetron sputtering process, the CrN films with sufficient adhesion performance was achieved in this work.

Superhard nanocomposite coatings of TiN/a-C prepared by reactive DC magnetron sputtering

Single layer TiN coatings were prepared on silicon (111) substrates using a multi-target reactive DC magnetron sputtering process at various nitrogen flow rates and substrate biases. TiN coatings prepared at a nitrogen flow rate of 0.6 sccm, a power density of 5.4 W/cm 2 and a substrate bias of −275 V, showed a nanoindentation hardness of 3300 kg/mm 2, whereas amorphous carbon (a-C) coatings prepared under similar deposition conditions exhibited a hardness of 800 kg/mm 2. Subsequently, nanocomposite coatings of TiN/a-C were prepared on silicon (111) and M3 tool steel substrates by rotating the substrate back and forth between the titanium and the graphite targets. The nanocomposite coatings were prepared at various carbon concentrations. Structural characterization of the coatings was done by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The compositions of the coatings were determined using energy dispersive X-ray analysis (EDAX). The nanocomposite coatings exhibited a broad (111) reflection of cubic TiN phase in XRD data. Nanoindentation data showed that about 1.5-μm-thick TiN/a-C nanocomposite coatings exhibited a maximum hardness of 4800 kg/mm 2 at a carbon concentration of approximately 17 at.%. The TEM micrographs showed that TiN nanocrystals were embedded in a-C matrix and the average crystallite size was 78 Å. The selected area electron diffraction of the nanocomposite coatings showed the presence of both nanocrystalline (TiN) and amorphous (a-C) phases. This was confirmed by high-resolution TEM studies.

Structure, hardness and thermal stability of TiAlN and nanolayered TiAlN/CrN multilayer films

TiAlN films were deposited on silicon (1 1 1) substrates from a TiAl target using a reactive DC magnetron sputtering process in Ar+N 2 plasma. Films were prepared at various nitrogen flow rates and TiAl target compositions. Similarly, CrN films were prepared from the reactive sputtering of Cr target. Subsequently, nanolayered TiAlN/CrN multilayer films were deposited at various modulation wavelengths ( Λ). X-ray diffraction (XRD), energy dispersive X-ray analysis, nanoindentation and atomic force microscopy were used to characterize the films. The XRD confirmed the formation of superlattice structure at low modulation wavelengths. The maximum hardness of TiAlN/CrN multilayers was 3900 kg/mm 2, whereas TiAlN and CrN films exhibited maximum hardnesses of 3850 and 1000 kg/mm 2, respectively. Thermal stability of TiAlN and TiAlN/CrN multilayer films was studied by heating the films in air in the temperature range ( T A) of 500–900 °C for 30 min. The XRD spectra revealed that TiAlN/CrN multilayers were stable up to 800 °C and got oxidized substantially at 900 °C. On the other hand, the TiAlN films were stable up to 700 °C and got completely oxidized at 800 °C. Nanoindentation measurements performed on the films after heat treatment showed that TiAlN retained a hardness of 2200 kg/mm 2 at T A=700 °C and TiAlN/CrN multilayers retained hardness as high as 2600 kg/mm 2 upon annealing at 800° C.