DC Reactive Magnetron Co-sputtering Research Articles

Impact of Silver Incorporation and Flash-Lamp-Annealing on the Photocatalytic Response of Sputtered ZnO Films.

Thin films of silver-doped zinc oxide (SZO) were deposited at room temperature using a DC reactive magnetron co-sputtering technique using two independent Zn and Ag targets. The crystallographic structure, chemical composition and surface morphology of SZO films with different silver concentrations were correlated with the photocatalytic (PC) properties. The crystallization of the SZO films was made using millisecond range flash-lamp-annealing (FLA) treatments. FLA induces significant structural ordering of the wurtzite structure and an in-depth redistribution of silver, resulting in the formation of silver agglomerates. The wurtzite ZnO structure is observed for silver contents below 10 at.% where Ag is partially incorporated into the oxide matrix, inducing a decrease in the optical band-gap. Regardless of the silver content, all the as-grown SZO films do not exhibit any significant PC activity. The best PC response is achieved for samples with a relatively low Ag content (2-5 at.%) after FLA treatment. The enhanced PC activity of SZO upon FLA can be attributed to structural ordering and the effective band-gap narrowing through the combination of silver doping and the plasmonic effect caused by the formation of Ag clusters.

Palladium enhanced electrochemical supercapacitive performance of chromium oxide thin films synthesized by sputtering process

Recently, the use of transition metal oxide electrodes for supercapacitor applications has increased due to the possibility of variable mixed valence states. The present study has established the use of Pd-Cr2O3 composite thin films as a working electrode for high-performance supercapacitors. The reactive dc magnetron co-sputtering method has been used for the fabrication of thin film of Cr2O3 and Pd-Cr2O3 on SS-304 substrate. X-ray diffraction and X-ray photoemission spectroscopy techniques were used to examine the surface chemistry and phase purity of chromium oxide and Pd-Cr2O3 composite thin films. The incorporation of Pd in Cr2O3 delivers a drastic change in the surface morphology. Due to the modified morphology and electronic properties, a noticeable improvement in the electrochemical properties of Pd-Cr2O3 electrode is observed. The obtained value of specific capacitance for this electrode is 401 Fg−1 at 0.1 mAcm−2 scan rate and within the potential window range 0 to +1.2 V. This value of specific capacitance is almost twice in comparison to the Cr2O3 based electrode. The Pd-Cr2O3 composite thin film shows a good cycle retention capability of 8000 cycles with 87.5 % retention. The obtained value of energy density and power density for Pd-Cr2O3 electrode was 80.2 Whkg−1 and 3.23 kWkg−1, respectively at 0.1 mAcm−2. Consequently, this composite material electrode can be seen as a promising advancement for electrodes in supercapacitor devices.

Pseudocapacitive Kinetics in Synergistically Coupled MoS2-Mo2N Nanowires with Enhanced Interfaces toward All-Solid-State Flexible Supercapacitors.

Pseudocapacitive kinetics in rationally engineered nanostructures can deliver higher energy and power densities simultaneously. The present report reveals a high-performance all-solid-state flexible symmetric supercapacitor (FSSC) based on MoS2-Mo2N nanowires deposited directly on stainless steel mesh (MoS2-Mo2N/SSM) employing DC reactive magnetron co-sputtering technology. The abundance of synergistically coupled interfaces and junctions between MoS2 nanosheets and Mo2N nanostructures across the nanocomposite results in greater porosity, increased ionic conductivity, and superior electrical conductivity. Consequently, the FSSC device utilizing poly(vinyl alcohol)-sodium sulfate (PVA-Na2SO4) hydrogel electrolyte renders an outstanding cell capacitance of 252.09 F·g-1 (44.12 mF·cm-2) at 0.25 mA·cm-2 and high rate performance within a wide 1.3 V window. Dunn's and b-value analysis reveals significant energy storage by surface-controlled capacitive and pseudocapacitive mechanisms. Remarkably, the symmetric device boosts tremendous energy density ∼10.36 μWh·cm-2 (59.17 Wh·kg-1), superb power density ∼6.5 mW·cm-2 (37.14 kW·kg-1), ultrastable long cyclability (∼93.7% after 10,000 galvanostatic charge-discharge cycles), and impressive mechanical flexibility at 60°, 90°, and 120° bending angles.

Effects of Y and Ho doping on microstructure evolution during oxidation of extraordinary stable Hf-B-Si-Y/Ho-C-N films up to 1500 °C

Hard, and optically transparent amorphous Hf6B12Si29Y2C2N45 and Hf5B13Si25Ho3C2N48 films were prepared by reactive pulsed dc magnetron co-sputtering and annealed up to 1500 °C in air. The evolved microstructures were studied by X-ray diffraction and transmission electron microscopy to understand the Y- and Ho– doping effects on thermal stability and oxidation behavior. A three-layered microstructure developed in both annealed films. A fully oxidized layer formed at the top surface consisting of cubic fluorite Hf(Y/Ho)O2 nanoparticles embedded in an amorphous SiOx-based matrix. The oxide layer is about 36 % thinner compared to undoped films with similar composition [1]. A recrystallized structure formed at the bottom of both films composed mainly of Hf(Y/Ho)N and α-/β-Si3N4. All Hf(Y/Ho)N in the middle layer was oxidized producing vertically oriented Hf(Y/Ho)O2 nanocolumns surrounded by Si3N4 nanocrystalline. The Y- and Ho– doping found to stabilize the cubic fluoride oxide structure and promoted its (1 1 1) columnar texture. The oxidation mechanism of Si3N4 nanodomains occurs via formation of β-SiO2 first followed by its transformation to amorphous SiOx. It is suggested that substitution of Hf4+ with Y3+ and Ho3+ ions within the Hf(Y/Ho)O2 formed an anion vacancy defect structure to preserve charge neutrality affecting the oxidation mechanism in the doped films.

Vanadium-Doped Ni/YSZ Anode Functional Layers for Solid Oxide Fuel Cells Produced via Magnetron Sputtering

The electrode performance of solid oxide fuel cells (SOFC) strongly depends on its microstructural characteristics, such as the porosity, percolated paths of ionically and electronically conductive phases and in particular, the grain size1. Deploying alternative manufacturing techniques that deposit nanostructured materials results in finer particle sizes and thus, increases the quantity of triple-phase boundaries. For that reason, the magnetron sputtering technique, which offers elemental distribution at the nanoscale, high deposition rates, reproducibility, scalability and excellent uniformity over large-area substrates has been chosen as the deposition method to fabricate anode functional layers (AFLs) for SOFCs.Nanostructured NiO-YSZ thin films have been previously produced by reactive pulsed DC magnetron co-sputtering of metallic targets of zirconium-yttrium and nickel, defining the optimal deposition parameters to create state-of the-art AFLs. Former studies reported limitations of the process control during reactive magnetron sputtering, regarding the film’s composition 1,2. Since the composition strongly relies on the amount of reactive gas, i.e., oxygen, present during deposition, a feedback control system is required to prevent oxygen built-up leading to target poisoning and lower deposition rates.Herein, we present a reactive feedback control system, that manages quantities of oxygen introduced to the sputtering chamber during deposition based on the oxygen partial pressure. This facilitates stable operation conditions, prevents target poisoning, and maintains the coating characteristics, i.e., its microstructure and desired composition when varying process parameters, such as the deposition pressure, target-substrate distance, or the deposition angle.Based on recent studies 3–5, the future of oxide-based anode materials for SOFCs will greatly focus on reducing the Ni catalyst content through alternative non-precious metal doping and increasing the cell performance by tailoring the microstructure of the AFL. This would allow Ni coarsening to be mitigated and maintain the nanostructure over the lifetime of the cell. Therefore, in this study complex transition metal oxides, such as vanadium, tantalum or manganese oxides, were doped into SOFC anodes to study their influence on the structural and morphological properties of magnetron sputtered AFL. The effect of dopant concentration on the properties of Ni-YSZ films in as-deposited, pre-annealed and reduced state was analysed using SEM, EDS, XRD and XPS. To characterise the electrochemical performance of the deposited films, polarisation curves were obtained from SOFC single stack assemblies under hydrogen and air flows for anode and cathode, respectively, at operating temperatures of 750, 800 and 850 ℃.References Lim, Y., Lee, H., Hong, S. & Kim, Y. B. Co-sputtered nanocomposite nickel cermet anode for high-performance low-temperature solid oxide fuel cells. J. Power Sources 412, 160–169 (2019).Ionov, I. V. et al. Reactive co-sputter deposition of nanostructured cermet anodes for solid oxide fuel cells. Jpn. J. Appl. Phys. 57, 30–34 (2018).Atkinson, A. et al. Advanced anodes for high-temperature fuel cells. Nat. Mater. 3, 17–27 (2004).Van Overmeere, Q. & Ramanathan, S. Thin film fuel cells with vanadium oxide anodes: Strain and stoichiometry effects. Electrochim. Acta 150, 83–88 (2014).Garcia-Garcia, F. J., Beltran, A. M., Yubero, F., Gonzalez-Elipe, A. R. & Lambert, R. M. High performance novel gadolinium doped ceria / yttria stabilized zirconia / nickel layered and hybrid thin film anodes for application in solid oxide fuel cells. J. Power Sources 363, 251–259 (2017). Figure 1

Vanadium-Doped Ni/YSZ Anode Functional Layers for Solid Oxide Fuel Cells Produced via Magnetron Sputtering

The electrode performance of solid oxide fuel cells (SOFCs) strongly depends on their microstructural characteristics, such as the porosity, percolated paths of ionically and electronically conductive phases and in particular, the grain size. Deploying alternative manufacturing techniques, such as magnetron sputtering, that deposits nanostructured materials results in finer particle sizes and thus, increases the quantity of triple-phase boundaries in the anode functional layer (AFL) for SOFCs. Nanostructured NiO-YSZ thin films have been previously produced by reactive pulsed DC magnetron co-sputtering of metallic targets of zirconium-yttrium and nickel, defining the optimal deposition parameters to create state-of-the-art AFLs. Based on recent studies 1–3, the future of oxide-based anode materials for SOFCs will greatly focus on advancing the electrocatalyst through alternative non-precious metal doping and increasing the cell performance by tailoring the microstructure of the AFL. Therefore, in this study, vanadium oxides were doped into SOFC anodes using different concentrations to study their influence on the structural and morphological properties of magnetron-sputtered AFLs.

Composite Assembling of Oxide-Based Optically Transparent Electrodes for High-Performance Asymmetric Supercapacitors.

Simultaneously achieving a transparent and high-energy density supercapacitor is a major challenge because of the trade-off between energy storage capacity and optical transparency of active electrode materials. Herein, we demonstrate a novel approach to construct an optically transparent asymmetric supercapacitor (Trans-ASC) by assembling positive (ZnO-SnO2) and negative (TiO2-SnO2) composite thin-film electrodes on a conductive indium-doped tin oxide substrate via reactive DC magnetron cosputtering. The optical transmittance for both composite thin films is found to be 68% (ZnO-SnO2) and 64% (TiO2-SnO2). Furthermore, electrochemical kinematics of the primed transparent electrodes are scrutinized in 0.5 M KOH electrolyte without affecting the transparency of active electrodes. The structural reliability of the electrodes aids the superb electrochemical performance to construct a Trans-ASC, TiO2-SnO2//ZnO-SnO2, which works at a voltage of +1.2 V and attains a higher areal capacitance of 44.6 mF cm-2 at 2 mA cm-2. The assembled Trans-ASC delivers a maximum areal energy density of 8.75 μW h cm-2 with an optimal areal power density of 570 μW cm-2. Additionally, the capacitance retention of 81.6% and transparency of both electrodes remain almost the same (up to 60% for ZnO-SnO2 and 62% for TiO2-SnO2) even after 10,000 charging-discharging cycles. These remarkable electrochemical properties and outstanding cycling stability of the designed Trans-ASC device make it a potential candidate for storing energy and for further use in transparent electronic devices.

Mechanical and tribological properties of Ti-Al-Ta-N/TiAl and Ti-Al-Ta-N/Ta multilayer coatings deposited by DC magnetron sputtering

The mechanical properties, microstructure, adhesion and wear behavior of a Ti0.41Al0.48Ta0.11N monolithic coating and Ti0.41Al0.48Ta0.11N/Ti0.45Al0.55 and Ti0.41Al0.48Ta0.11N/Ta multilayers were investigated. The coatings were deposited on titanium substrates by reactive DC magnetron co-sputtering. The hardness and reduced elastic modulus of the coatings were determined by nanoindentation. The multilayer coatings were found to exhibit the lower mechanical characteristics than those of the monolithic coating due to the contribution of the softer metal interlayers to their measured values. Adhesion evaluation was performed by scratch testing. The Ti0.41Al0.48Ta0.11N/Ti0.45Al0.55 multilayer was characterized by stronger adhesion to the titanium substrate than the monolithic coating, whereas the Ti0.41Al0.48Ta0.11N/Ta multilayer exhibited poorer adhesion. In contrast, both the multilayers showed improved wear resistance compared with the monolithic coating. The best wear performance was demonstrated by the Ti0.41Al0.48Ta0.11N/Ti0.45Al0.55 multilayer that was attributed to stronger bonding between the layers as well as the lower hardness of the Ti0.45Al0.55 layers, which allowed for the accommodation of a larger amount of deformation via their plastic flow.

Photocatalytic activity of TiO2/SiO2 nanocomposites synthesized by reactive magnetron sputtering technique

TiO2 / SiO2 nanocomposites were synthesized by DC reactive magnetron cosputtering technique using different O2 : Ar gas mixing ratios. The structural and spectroscopic characteristics of the synthesized samples were introduced using x-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy, energy-dispersive x-ray spectroscopy, and UV-visible spectroscopy. The XRD results revealed that all nanocomposite samples were polycrystalline. The functional groups of these samples were identified by FTIR. The UV-visible spectra of these samples showed an absorption edge at 450 nm. The results of photodegradation of organic and water pollutants under UV irradiation suggest that the photocatalytic activity of TiO2 / SiO2 nanocomposite is highly improved as compared with that of TiO2 nanophotocatalyst.

Durability-enhanced monolithic inorganic electrochromic devices with tantalum-doped nickel oxide as a counter electrode

Nickel oxide (NiO) is a well-known electrochromic (EC) material with anodic coloration. However, NiO degrades significantly upon cycling with Li + /H + -conducting electrolytes. Doping with various additives is the most effective method to enhance the cycling stability of NiO films. In this study, films of tantalum-doped nickel oxide, denoted as Ni 1- x Ta x oxide, were deposited onto indium tin oxide (ITO)-coated glass substrates by reactive DC magnetron co-sputtering from Ni and Ta metal targets for use as counter electrodes in monolithic inorganic EC devices (ECDs). The influence of the Ta content on the composition, structure, optical properties and EC properties of NiO was investigated. It was found that the microstructure of the Ni 1- x Ta x oxide films was closely related to the EC performance and cycling stability. With moderate optical modulation, the cycling stability and optical transmittance of the Ni 1- x Ta x oxide film with x = 0.274 were increased. All-solid-state inorganic ECDs were fabricated with the configuration ITO/WO 3 /Ta 2 O 5 /Ni 1- x Ta x oxide/ITO/glass. The full ECDs showed different EC behaviors compared to those of the Ni 1- x Ta x oxide single layers, which was attributed to the different counter electrode/ion conductor interfaces of the solid–solid and solid–liquid interfaces, respectively. The ECD fabricated with the Ni 1- x Ta x oxide film with x = 0.065 showed stable transmittance modulation up to 1000 cycles. We propose a degradation mechanism for monolithic all-solid-state inorganic ECDs based on the observed degradation in the EC performance, which can pave the way for highly durable ECDs for various optoelectronic devices. • Ta-doped Ni oxides were prepared by reactive DC magnetron co-sputtering with Ta content between 0.065 and 0.490. • A Ta content of 0.274 led to the most stable cycling stability with moderate optical modulation. • Ni 1- x Ta x oxide with x = 0.065 is an excellent electrochromic material for highly reliable electrochromic devices.

Tantalum-Titanium Oxynitride Thin Films Deposited by DC Reactive Magnetron Co-Sputtering: Mechanical, Optical, and Electrical Characterization

The possibility to tune the elemental composition and structure of binary Me oxynitride-type compounds (Me1Me2ON) could lead to attractive properties for several applications. For this work, tantalum-titanium oxynitride (TaTiON) thin films were deposited by DC reactive magnetron co-sputtering, with a –50 V bias voltage applied to the substrate holder and a constant substrate temperature of 100 °C. To increase or to decrease in a controlled manner, the Ti and Ta content in the co-sputtered films, the Ti and Ta target currents were varied between 0.00 and 1.00 A, in 0.25 A steps, while keeping the sum of the currents applied to the two targets at 1.00 A. The reactive gases flow, consisting of a nitrogen and oxygen gas mixture with a constant N2/O2 ratio (85%/15%), was also kept constant. The single-metal oxynitrides (TaON and TiON) showed a low degree of crystallinity, while all the other co-sputtered films revealed themselves to be essentially amorphous. These two films also exhibited higher adhesion to the metallic substrate. The TaON film showed the highest hardness value (14.8 GPa) and the TiON film a much lower one (8.8 GPa), while the co-sputtered coatings exhibited intermediary values. One of the most interesting findings was the significant increase in the O content when the Ti concentration surpassed the Ta one. This significantly influenced the optical characteristic of the films, but also their electrical properties. The sheet resistivity of the co-sputtered films is strongly dependent on the O/(Ta + Ti) atomic ratio.

Fabrication of an acetone gas sensor based on Si-doped WO3 nanorods prepared by reactive magnetron co-sputtering with OAD technique

Gas sensing technology is currently applied in a variety of applications. In medical applications, gas sensors can be used for the detection of the biomarker in various diseases, metabolic disorders, diabetes mellitus, asthma, renal, liver diseases, and lung cancer. In this study, we present acetone sensing characteristics of Si-doped WO3 nanorods prepared by a DC reactive magnetron co-sputtering with an oblique-angle deposition (OAD) technique. The composition of Si-doped in WO3 has been studied by varying the electrical input power applied to the Si sputtered target. The nanorods film was constructed at the glancing angle of 85°. After deposition, the films were annealed at 400 °C for 4 h in the air. The microstructures and phases of the materials were characterized by x-ray photoelectron spectroscopy (XPS), x-ray diffraction (XRD), and field-emission scanning electron microscopy (FESEM). The results showed that 1.43 wt% Si-doped WO3 thin film exhibited the maximum response of 5.92 towards 100 ppm of acetone at performing temperature (350 °C), purifying dry air carrier. The process exposed in this work demonstrated the potential of high sensitivity acetone gas sensor at low concentration and may be used as an effective tool for diabetes non-invasive monitoring.

Effect of Zr content on the structure and morphology of CrZrN thin films prepared by reactive DC magnetron co-sputtering method

In this research, nanostructured chromium zirconium nitride (CrZrN) thin film has been deposited on Si(100) substrates by reactive DC magnetron co-sputtering method without in situ substrate heating and post-deposition annealing. The effects of Zr content on thin film structure and morphology were investigated. The Zr content in the films were varied by applied the sputtering current of Zr target (Izr) in the range of 300 to 900 mA, whereas the current of Cr target was kept at 300 mA. The crystal structure, microstructure, morphology, thickness, and chemical composition were characterized by glancing angle X-ray diffraction (GA-XRD), field emission scanning electron microscopy (FE-SEM), and energy-dispersive X-ray spectroscopy (EDS) techniques, respectively. The results showed that the increase of Izr not only increased the deposition rate, but also increased the Zr content of the as-deposited film ranging from 3.9 to 26.5 at%. The as-deposited thin films were formed as a (Cr,Zr)N solid solution, with fcc structure in (111) and (200) plane, where Cr atoms were replaced by Zr atoms in the CrN lattice. The 2θ diffraction peaks were shifted to the lower value as increase of Zr content which was obtained by increased Izr. The nanocrystalline CrZrN structure with crystal sizes smaller than 10 nm structure were calculated for as-deposited thin films. The lattice parameters increased from 4.187 to 4.381 Å, whereas the crystal size decreased from 8.3 to 6.4 nm. The FE-SEM images of all the CrZrN films exhibited compact columnar with dense morphology as a function of Zr content. Moreover, the thickness of the CrZrN thin films was increased of 302 – 421 nm.

Approaching Theoretical Band Gap of ZnSnN2 Films via Bias Magnetron Cosputtering at Room Temperature

Zinc tin nitride (ZnSnN2) is a promising semiconductor candidate for solar cell applications and optoelectronic devices. However, the practical use of this material has been limited by several issues as, among others, oxygen contamination, a very high concentration of free carriers, and the difficulty to reach the theoretically predicted band gap. Here, we deposit thin films of ZnSnN2 by reactive DC magnetron cosputtering at room temperature with an RF bias power (Pb) in the range of 0–50 W. Using first principles calculations, we explore the structural and optoelectronic properties that are favorably compared to experimental results. We demonstrate that the optical band gap energy can be decreased from 1.7 to 1.34 eV, close to the predicted value of 1.37 eV. The free electron concentration is decreased down to 1017 cm–3 which results in the reduction of the absorption by free electrons in the IR range. In addition, in a given range of applied bias powers, we observe a densification of the films and a significant decrease of their oxygen contamination from 6.7 down to 2.0 at. %. The study underlines that a value of 20 W power bias leads to the optimal structural, optical, and electrical properties. Our results provide an interesting method to obtain a potential candidate for photovoltaic applications, in an environmentally friendly way, for low-cost industrialization.

Effect of Ar/N2 flow ratio on the microstructure and mechanical properties of Ti-Cr-N coatings deposited by DC magnetron sputtering on AISI D2 tool steels

Ti-Cr-N coatings were deposited on Si (100) and AISI D2 tool steel substrates by reactive DC magnetron co-sputtering technique from titanium and chromium target in mixed Ar/N2 atmosphere. The Ar/N2 ratio effects on the chemical composition, structure, morphology, intrinsic stress and mechanical properties of the Ti-Cr-N coatings were investigated. The growing process of Ti-Cr-N coatings can be divided into three stages: Stage I, in poisoning mode (low flow ratio 1 < Ar/N2 ≤ 1.4), Stage II, in transition mode (intermediate flow ratio 1.4 ≤ Ar/N2 ≤ 3) and Stage III in metallic mode (Ar/N2 > 3). For all samples, XRD analysis shown the formation of mixed nitrides phases. In stage I, Ti2N, TiN0.3, and hexagonal-Cr2N phases were observed. In Stage II, TiN0.3, Cr2N, and cubic-TiN phases were formed, while only TiN and Cr2N are observed in stage III. The coatings deposited with Ar/N₂ ratio of 3 shows the largest hardness of 24 GPa which is attribute to the dense structure and smoother surface morphology. The properties of the films are discussed in terms of evolution growth stages resulting by the variation of Ar/N2 flow ratios.

Magnetron co-sputtered Bi12TiO20/Bi4Ti3O12 composite – An efficient photocatalytic material with photoinduced oxygen vacancies for water treatment application

Bi12TiO20/Bi4Ti3O12 composite photocatalyst was investigated as an alternative to the conventionally used titanium dioxide, to tackle the well-known drawbacks of fast charge-carriers recombination and low quantum efficiency of TiO2. Polycrystalline Bi12TiO20/Bi4Ti3O12 thin films were produced by pulsed DC reactive magnetron co-sputtering, a method of high industrial relevance, and compared to titanium dioxide coatings produced with the same technique. Following the deposition process, optimum thermal treatment temperature and length were established, to obtain crystallisation. The synthesised coatings were thoroughly analysed with a range of techniques, including Raman spectroscopy, XRD, SEM, TEM, EDX, XPS and AFM. The photocatalytic properties of Bi12TiO20/Bi4Ti3O12 composite were assessed through methylene blue degradation and E. coli inactivation tests under UV-A irradiation. The results indicated considerably higher efficiency of the composite photocatalyst when compared to TiO2. Moreover, the reusability assessment of Bi12TiO20/Bi4Ti3O12 thin films revealed an incremental performance increase after each consecutive test, leading to a 6-fold increase in photocatalytic activity between the first and 15th cycle. Time-resolved photoluminescence and XPS analysis highlighted an increased presence of oxygen vacancies, forming over repeated usage of bismuth titanate, leading to longer lifetimes of photogenerated species and enhanced photocatalytic performance.

Co-sputtering of hbox {Al}_{1-x}hbox {Sc}_{x}hbox {N} thin films on Pt(111): a characterization by Raman and IR spectroscopies

In this work, aluminium scandium nitride (hbox {Al}_{1-x}hbox {Sc}_{x}hbox {N}) thin films are deposited by reactive DC magnetron co-sputtering on Pt(111) layers. The sputtering power of the Sc target is varied in a broad range up to 900 W to effectively vary the Sc content later assessed using energy-dispersive X-ray spectroscopy (EDX). We show that commonly used X-ray diffraction techniques may yield ambiguous results, and thus, additional verification is crucial to substantiate the actual composition of the sputtered thin films. Therefore, we employ optical spectroscopy techniques, such as Raman and Fourier transformed infra-red (FTIR) spectroscopies in order to study the vibrational properties of the alloys. Our Raman spectra show that low Sc content leads to a phase separation with the formation of cubic ScN and AlScN phases during the sputtering process. Nevertheless, small amounts of the wurtzite phase are detected in the rock-salt dominated samples owing to the enhancement of the hbox {A}_{{1}}(LO) phonon mode by the Berreman effect in the FTIR spectra. The Sc-induced shifts of the AlN phonon modes are determined in a broad range of Sc content.

Structure, stress, and mechanical properties of Mo-Al-N thin films deposited by dc reactive magnetron cosputtering: Role of point defects

In this work, the structural and mechanical properties of ternary Mo-Al-N alloys are investigated by combining thin film growth experiments and density functional theory (DFT) calculations. Mo1−xAlxNy thin films (∼300 nm thick), with various Al fractions ranging from x = 0 to 0.5 and nitrogen-to-metal (Al + Mo) ratio ranging from y = 0.78 to 1.38, were deposited by direct-current reactive magnetron cosputtering technique from elemental Mo and Al targets under Ar + N2 plasma discharges. The Al content was varied by changing the respective Mo and Al target powers, at a fixed N2 (20 SCCM) and Ar (25 SCCM) flow rate, and using two different substrate temperatures Ts = 350 and 500 °C. The elemental composition, mass density, crystal structure, residual stress state, and intrinsic (growth) stress were examined by wavelength dispersive x-ray spectroscopy, x-ray reflectivity, x-ray diffraction, including pole figure and sin2ψ measurements, and real-time in situ wafer curvature. Nanoindentation tests were carried out to determine film hardness H and elastic modulus EIT, while the shear elastic constant C44 was measured selectively by surface Brillouin light spectroscopy. All deposited Mo1−xAlxNy films have a cubic rock-salt crystal structure and exhibit a fiber-texture with a [001] preferred orientation. The incorporation of Al is accompanied by a rise in nitrogen content from 44 to 58 at. %, resulting in a significant increase (2%) in the lattice parameter when x increases from 0 to 0.27. This trend is opposite to what DFT calculations predict for cubic defect-free stoichiometric Mo1−xAlxN compounds and is attributed to variation in point defect concentration (nitrogen and metal vacancies) when Al substitutes for Mo. Increasing Ts from 350 to 500 °C has a minimal effect on the structural properties and phase composition of the ternary alloys but concurs to an appreciable reduction of the compressive stress from −5 to −4 GPa. A continuous increase and decrease in transverse sound velocity and mass density, respectively, lead to a moderate stiffening of the shear elastic constant from 130 to 144 GPa with increasing Al fraction up to x = 0.50, and a complex and nonmonotonous variation of H and EIT is observed. The maximum hardness of ∼33 GPa is found for the Mo0.81Al0.19N1.13 film, with nitrogen content close to the stoichiometric composition. The experimental findings are explained based on structural and elastic constant values computed from DFT for defect-free and metal- or nitrogen-deficient rock-salt MoAlN compounds.

Effect depositions parameters on the characteristics of Ni0.5Co0.5Fe2O4 nanocomposite films prepared by DC reactive magnetron Co-Sputtering technique

In this work, spinel ferrites (NiCoFe2O4) were prepared as thin films by dc reactive dual-magnetron co-sputtering technique. Effects of some operation parameters, such as inter-electrode distance, and preparation conditions such as mixing ratio of argon and oxygen in the gas mixture, on the structural and spectroscopic characteristics of the prepared samples were studied. For samples prepared at inter-electrode distance of 5 cm, only one functional group of OH- was observed in the FTIR spectra as all bands belonging to the metal-oxygen vibration were observed. Similarly, the XRD results showed that decreasing the pressure of oxygen in the gas mixture lead to grow more crystal planes in the samples prepared at inter-electrode distance of 5 cm. The energy band gap was determined for the sample prepared with mixing ratio of 65:35 and found to be 2.7, 2 and 3.35 eV for direct allowed, direct forbidden and indirect allowed transitions, respectively. The high structural purity was confirmed as no traces for any elements other than Co, Ni, Fe and O were found in the final samples.

Photocatalytic activity of Ag-doped TiO2 nanostructures synthesized by DC reactive magnetron co-sputtering technique

In this work, silver-doped titanium dioxide (Ag-doped TiO2) nanostructures synthesized by a dc reactive magnetron co-sputtering technique at different gas mixing ratios (Ar:O2). The structural and spectroscopic characteristics of the prepared samples were introduced by X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy and UV–visible spectroscopy. The XRD results reveal that all samples have anatase phase of tetragonal system. The functional groups of these samples were identified by FTIR. The shift in absorption edge to longer wavelength (from 387.5 to 418.9 nm) and higher absorption in the visible light region were observed. The results of photodegradation of the organic pollutant (methylene blue) using visible light irradiation (λ > 400 nm) suggest that the TiO2 photocatalyst was highly improved after doped with silver as compared with the undoped TiO2 photocatalyst.