Effects of annealing on wettability and physical properties of SnO thin films deposited at low RF power densities

The SnO thin films were deposited at low RF power densities by RF magnetron sputtering. According to XRD and XPS analyses, the SnO thin film comprised nanocrystalline orthorhombic SnO with a (110) orientation. Reducing RF power density resulted in better nanocrystallinity, changing hydrophobicity to hydrophilicity, and increasing the optical transmission in the UV–vis–NIR region. After annealing, the SnO thin film favored p-type conductivity and hydrophilicity. As the annealing temperature increased, the coexistence of nanocrystalline orthorhombic SnO and tetragonal SnO₂ in the film clearly increased the optical transmission in the ultraviolet region. The SnO thin films after annealing at 500 ℃ in vacuum and N₂ (200 sccm) exhibited a higher hole mobility and a better optical selection in the ultraviolet region, respectively.     

Optical and electrical properties of Al doped ZnO thin film with preferred orientation in situ grown at room temperature

To optimize the process and obtain highly conducting and transparent Aluminum-doped zinc oxide (AZO) thin films, AZO films were deposited on glass substrates at room temperature by Radio-frequency (RF) magnetron sputtering with various Argon flow rates. The influences of Argon flow rate on structure, morphology, optical, electrical and photoluminescence properties of AZO films were investigated by varying the Argon flow rate from 36 to 68 sccm. The best quality AZO film with resistivity 1.39 × 10⁻³ Ω cm, sheet resistance 8.2 Ω/sq and 84.2% average visible transmittance was prepared at 44 sccm for 30 min. Also, the self-heating effect of target was investigated by preparing AZO films for 10 min and 20 min at 44 sccm, 180 W and 1.0 Pa. The influence of increasing structural quality actually affected by Argon flow rate was more prominent on carrier concentration than mobility. The schematic illustration of microstructural evolution was proposed. The average growth rate of around 60 nm/min demonstrated the self-heating effect of target was weak and could be ignored.     

氮氩气流量比对磁控溅射氮化钛薄膜微观结构的影响

采用扫描电镜(SEM)和X射线衍射仪(XRD)研究了氮气流量(5、10、25、50 sccm)及氮氩气流量比(4∶1、3∶2、2∶3、1∶4)对磁控溅射TiN薄膜微观形貌和相组成的影响。结果显示,所得样品具有纳米级TiN薄膜的基本特征。当N2与Ar的总流量为5 sccm,而它们的流量比为4∶1时,可以制得品质较好的蓝紫色TiN薄膜。     

Characteristics of Li–P–W–O–N electrolyte for all solid state electrochromic devices

A LiPON–WO₃ composite thin film (LPWON) was evaluated for use as a solid electrolyte in solid state electrochromic (EC) devices. LiPO₄ and a WO₃ (2 wt%) composite sputtering target was synthesized by a ball milling process. The LPWON thin films were deposited by RF magnetron sputtering in Ar + N₂ and N₂ atmospheres. The structural, electrochemical, and optical properties of the LPWON electrolytes were characterized by X-ray diffraction (XRD), UV–visible spectroscopy, and an impedance analyzer. EC mirrors with WO₃ (coloring layer), LPWON (solid electrolyte), and stainless steel (mirror electrode) on ITO (transparent electrode) glass were fabricated to analyze the improved EC properties due to the LPWON electrolyte. The LPWON may lead to electrolytes with more stable potential cycle properties.     

Growth and Characterization of Tungsten Oxide Thin Films using the Reactive Magnetron Sputtering System

WO₃ thin film is one of the most important and applied metal oxide semiconductors that have attracted the scientist’s attention in recent decades. WO₃ thin films by two different methods: reactive and non-reactive RF magnetron sputtering deposited on soda lime glass. The effect of presence and absence of oxygen gas in system and RF power on structural, morphological and optical properties of thin films were investigated. The XRD analysis of the films shows the amorphous structure. Spectrophotometer analysis and calculation show that the optical properties of reactive sputtered layers were better than the non-reactive sputtered thin films. By changing deposition parameters, over 70 % transmission achieved for WO₃ films. The results showed that reactive sputtering method improved the optical properties of layers and increased band gap up to 3.49 eV and on the other hand reduced roughness of thin films. On the whole, presence of oxygen in the chamber during sputtering improved properties of WO₃ thin films.     

Effects of nitrogen flow rate on the microstructure and mechanical and tribological properties of TiAlN films prepared via reactive magnetron sputtering

In this study, TiAlN ceramic films were fabricated via reactive magnetron sputtering on a Ti6Al4V titanium alloy substrate. The effects of N₂ flow rates on the microstructure and mechanical and tribological properties of the films were systematically studied. With increasing N₂ flow rate, the films underwent a morphological evolution from a fine columnar structure to a coarse structure with holes and microcracks. In addition, the preferred orientation of the films varied from TiAlN (220) to the (111) plane. However, a high N₂ flow rate (≥20sccm) resulted in target poisoning and reduced the deposition rate, which resulted in defects such as cavities and holes on the surface. Moreover, with increasing N₂ flow rate, the hardness and elastic modulus first increased and then reduced owing to grain refinement. The films deposited at a N₂ flow rate of 16 sccm exhibited the smallest wear width and the lowest wear rate. As the N₂ flow rate increased from 12 to 24 sccm, the wear mechanism of the films changed from abrasive and adhesion wear to abrasive wear caused by severe plastic deformation, which was directly related to the microstructural evolution and mechanical properties.     

Influence of N2 flow rate on microstructure and properties of CrNx ceramic films prepared by MPP technique at low temperature

In this study, CrN_x ceramic films were prepared utilizing modulated pulsed power magnetron sputtering (MPP) technique at low deposition temperature, with varying flow rates of the reactive gas, i.e. N₂. The influences of N₂ flow rate on the density of the plasma surrounding the target sheath, microstructure evolution, mechanical/tribological and anti-corrosion properties of the as-deposited CrN_x ceramic films were investigated systematically. Results indicated that the plasma density increased sharply with increasing N₂ flow rate in the range of 75 sccm to 175 sccm. Nevertheless, with further increase of N₂ flow rate to 200 sccm, the growing trend of ionization slowed down probably due to the insufficiency of the power density. With increasing N₂ flow rate, the Cr elemental concentration decreased from 69.7 at.% to 57.5 at.%, and that of N increased from 23.2 at.% to 36.6 at.%. The sub-stoichiometric ratio of the CrN films could be attributed to the relative lower reactive kinetic energy at low deposition temperature. The analyses on the microstructure evolution of CrN_x films revealed that with insufficient introduced nitrogen, competitive growth between Cr₂N(110), Cr₂N(111), Cr(110) phases (note that all crystalline planes indexed here are parallel to the coating surface) were found; and with relative sufficient nitrogen, fcc-CrN phase took over, with preferred orientation of (111). Due to the improvement of density and the fine-grain strengthening mechanism, with 100 sccm N₂ flow rate, the hardness of the CrN_x films obtained the maximum value of 21.4 GPa. The films deposited at 75 sccm nitrogen showed the highest friction coefficient (i.e. ~0.75), which could be partially attributed to the presence of impurity particles on the film surface. And for the remaining films, the friction coefficient maintained in the range of 0.38–0.52. As for the anti-corrosion properties, the CrN_x film deposited at 100 sccm nitrogen showed the lowest corrosion current (i.e. 44.2 nA/cm²), indicating excellent anti-corrosion property.     

The effect of a buffer layer on the structure and the performance of cutting-tools for ZrWN films that are deposited using DCMS and HIPIMS

This paper determines the optimal settings for the deposition of ZrWN nitride films using reactive direct current magnetron sputtering (DCMS) and high-power impulse magnetron sputtering (HIPIMS), with pure Zr and W metal targets and Ar plasma and N₂ reactive gases. The materials tested as buffer layers are metal tungsten (W) and tungsten nitride (WN) thin films. Using a Taguchi method, this study determines the effect of deposition parameters for the buffer layer (W DC power, substrate bias, N₂/(N₂+Ar) flow rate and substrate temperature) on the structural and mechanical properties, and the dry machining performance of cutting-tools for multilayer ZrWN/W and ZrWN/WN/substrates. In the confirmation runs using grey Taguchi analysis, there is an improvement of 32.31% and 13.38% in surface roughness and flank wear, respectively. The films are characterized using X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), transmission electron microscopy (FEI-TEM) and a nanoindenter. The TEM pattern for the ZrWN films shown corresponds to the (111), (200) and (220) planes of the face-center-cubic phase. Pretreatment of a tungsten carbide tool uses oxygen plasma etching to enhance the adhesion of the multilayer ZrWN/WN coating. Compared with coatings that are deposited using DCMS, the samples that are deposited using HIPIMS exhibit a higher film density and a smoother surface. In the HIPIMS mode, the XRD diffraction peaks of the films are sharper and more intense, which indicates an improvement in crystallinity.     

Structures,morphological control,and antibacterial performance of tungsten oxide thin films

The present work describes structural, morphological, and antibacterial properties of thin film coatings based on tungsten oxide material on stainless-steel substrates. Thin films were prepared by RF magnetron sputtering of W targets in the oxygen/argon plasma environment in 60 W sputtering power. The characterization of the specimens was made on the basis of microstructure and antibacterial properties of the thin films surface. The effect of O₂/Ar ratio on the structure, morphology, and antibacterial properties of the tungsten oxide thin films was studied. Methods such as X-ray diffraction (XRD), scanning electron microscope (SEM), and Fourier Transform Infrared Spectroscopy (FTIR) were used to assess the properties of deposited thin films. XRD peak analysis indicates (100) and (200) of WO₃ phase with hexagonal structure. Moreover, the micro-strain, grain size, and dislocation density were obtained. It is noteworthy that by increasing the oxygen percentage from 10% to 20%, the grain size decreases from 81 to 23 nm while the film micro-strain and dislocation density increases. The SEM results illustrates that tungsten oxide thin films are made of interconnected nano-points in a chain shape with sphere-shaped grains with diameter variation from 10 to 100 nm. The FTIR spectra displays four distinct bands corresponds to O–W–O bending modes of vibrations and W–O–W stretching modes of the WO₃ films. The antibacterial effects of tungsten oxide thin films on steel stainless substrate against Escherichia coli bacteria are also examined for the first time and our observation shows that the number of bacteria on all tungsten oxide samples decreases after 24 h. The samples exhibit an excellent antibacterial performance. This paper renders a strategy through which the tungsten oxide thin films for antibacterial purpose and proposes that WO₃ thin films are ideal for various medical applications including stainless steel medical tools, optical coatings, and antibacterial coatings.     

Preparation of diamond like carbon thin films above room temperature and their properties

Diamond like carbon (DLC) thin films were deposited on p-type silicon (p-Si), quartz and ITO substrates by microwave (MW) surface-wave plasma (SWP) chemical vapor deposition (CVD) at different substrate temperatures (RT ∼ 300 °C). Argon (Ar: 200 sccm) was used as carrier gas while acetylene (C₂H₂: 20 sccm) and nitrogen (N: 5 sccm) were used as plasma source. Analytical methods such as X-ray photoelectron spectroscopy (XPS), FT-IR and UV–visible spectroscopy were employed to investigate the structural and optical properties of the DLC thin films respectively. FT-IR spectra show the structural modification of the DLC thin films with substrate temperatures showing the distinct peak around 3350 cm^− 1 wave number; which may corresponds to the sp² C–H bond. Tauc optical gap and film thickness both decreased with increasing substrate temperature. The peaks of XPS core level C 1 s spectra of the DLC thin films shifted towards lower binding energy with substrate temperature. We also got the small photoconductivity action of the film deposited at 300 °C on ITO substrate.     

Piezo-ferroelectric response of bismuth ferrite based thin films and their related photo/piezocatalytic performance

Bismuth ferrite based thin films were grown by RF magnetron sputtering under different experimental conditions. The effects of substrate temperature, Ar:O₂ mass flow ratio and gas mixture pressure on the films’ microstructure, phase evolution, optic, ferroelectric and magnetic properties were systematically investigated. The structural analysis results revealed an amorphous phase for the films deposited at a substrate temperature below 500 °C, while for the thin films deposited at 700 °C, a ε-Fe₂O₃ secondary phase was detected. The diffraction lines of the samples deposited at 600 °C were associated with Bi₂Fe₄O₉ and Bi₂₅FeO₄₀ phases. The increase in the mixture gas pressure up to 1 Pa showed an improved crystallinity of the deposited films, while, at higher working gas pressures, the films were found to be amorphous. The use of low O₂ to Ar mass flow ratio during the deposition led to a phase transformation process. EDX and RBS measurements exposed a uniform distribution of the main elements, revealing some stoichiometry changes induced by the pressure variation. The optical band gap values were influenced by the substrate temperature and pressure of the Ar:O₂ gas. The magnetic properties were correlated with the structural features, the highest magnetic response being observed for the sample deposited at 600 °C, 1 Pa and 3:1 Ar:O₂ gas pressure. According to the PFM results, the film deposited at 700 °C, Ar:O₂ ratio 3:1 and total gas pressure 1 Pa clearly outperformed the others due to their excellent ferroelectric properties and outstanding piezo-response. The sample deposited at 700 °C showed both visible light-driven degradation and piezodegradation activities. The piezocatalytic and photocatalytic activities were ascribed to the high piezoresponse and to a more efficient separation of electrons and holes induced by a built-in electric field that is caused by the larger remnant polarization of Bi₂Fe₄O₉ and Bi₂Fe₄O₉/ε-Fe₂O₃ hetero-junction.     

Optimization of DC Reactive Magnetron Sputtering Deposition Process for Efficient YSZ Electrolyte Thin Film SOFC

Yttria‐stabilized zirconia (YSZ, ZrO₂:Y₂O₃) thin films were deposited by reactive DC magnetron sputtering with a high deposition rate from a metallic target of Zr/Y in an argon/oxygen atmosphere. Plasma parameters and composition analysis of the gas phase reveal that the sputtering process in the “compound” mode is reached for a 2.5 sccm oxygen flow rate. Deposition onto silicon in “metal” mode at a flow rate close to the transition, allows obtaining at very high deposition rates (>10 μm h^–1) a compact columnar stoichiometric crystallized YSZ film. When deposited on NiO‐YSZ commercial anode, the obtained coatings show the same properties. In spite of the complexity of the substrate (roughness and porosity), a compact and conformed layer was formed. Annealing treatments in air or hydrogen do not significantly alter the structure of the layers. Electrochemical test at 850 °C with a screen‐printed LSM (LaSrMnO₃) cathode exhibits a satisfying gastightness (OCV = 900 mV) and a maximum power density of 350 mW cm^–2.     

Impact of Stoichiometry on Structural and Optical Properties of Sputter Deposited Multicomponent Tellurite Glass Films

Multicomponent TeO₂–Bi₂O₃–ZnO (TBZ) glass thin films were prepared using RF magnetron sputtering under different oxygen flow rates. The influences of oxygen flow rate on the structural and optical properties of the resulting thin films were investigated. We observed that thin films sputtered in an oxygen‐rich environment are optically transparent while those sputtered in an oxygen‐deficient environment exhibit broadband absorption. The structural origin of the optical property variation was studied using X‐ray diffraction, X‐ray photoelectron spectroscopy, Raman Spectroscopy, and transmission electron microscopy which revealed that the presence of under‐coordinated Te leads to the observed optical absorption in oxygen‐deficient films.     

Controlled growth of nanocrystalline aluminum nitride films for full color range

Color films are widely used for visual effect as well as for their functional properties. To date, however, synthesizing thin films with desired color remains challenging. In this work, AlN color films are deposited on Si wafers by precise control of the deposition time for different thickness during reactive magnetron sputtering from an Al target in Ar/N₂ atmosphere. The thickness, morphology, structure, composition and color index are carefully examined by field emission scanning electron microscopy, atomic force microscopy, grazing incidence X-ray diffraction, X-ray photoelectron spectrometry and colorimeter, respectively. As the film thickness changes from 57 nm to 165 nm, the film exhibits purple, indigo, blue, green, yellow, orange and red in color. These colors repeat in the same order when the thickness goes over 165 nm. Once the thickness exceeds 467 nm, overlapping of colors takes place. The mechanisms are elucidated.     

Solid oxide fuel cells with YSZ-BNO Bi-layer electrolyte film deposited by magnetron sputtering

Bi-layer electrolyte films of Zr_0.84Y_0.16O_1.92 (YSZ)- 0.79Bi₂O₃-0.21Nb₂O₅ (BNO) were deposited by RF magnetron sputtering on NiO-SDC anode substrates. The stoichiometry of the BNO electrolyte film was found strongly dependent on the ratio of Ar and O₂ during sputtering, and the BNO film deposited at a mixture of 31 sccm Ar and 7 sccm O₂ appeared to be the closest to the target composition. When deposited at 300 °C and subsequently annealed at 700 °C, the BNO electrolyte emerged to be crack free and dense with some scattering closed pores. The XRD patterns of the film are indexed to the cubic Fm m structure of Bi₃NbO₇. The as-deposited film was well-crystalline and consisted of fine grains and random orientation microstructures. For electrolyte thicknesses of approximately 4.0 μm YSZ and 1.5 μm BNO layers, the open circuit voltage (OCV) and the maximum power density of the single cell with Ag cathode read respectively 0.94 V and 10 mW/cm² at 600 °C. These OCV values are lower than the expected theoretical value due to the high partial electronic conductivity.     

(AlCrNbSiTiV)N高熵合金氮化薄膜溅镀参数的灰关联分析优化

采用直流反应式磁控溅镀法在硅晶片和住友刀具BN2000上制备(AlCrNbSiTiV)N高熵合金氮化薄膜。通过正交试验考察了溅镀功率、沉积温度、氮氩气流量比和基材偏压对薄膜的摩擦因数、硬度和刀具磨损的影响。对信噪比进行灰关联分析,以实现多目标优化,得出最佳工艺参数为:溅镀功率200 W,沉积温度200°C,氮氩气流量比0.3,基材偏压100 V。该条件下所得薄膜的摩擦因数为0.46,显微硬度为1243.72 HV,刀具磨损最小。     

Characteristics of nitrogen doped diamond-like carbon thin films grown by microwave surface-wave plasma CVD

Nitrogen doped diamond-like carbon (DLC:N) thin films were deposited on p-type silicon (p-Si) and quartz substrates by microwave (MW) surface-wave plasma (SWP) chemical vapor deposition (CVD) at low temperature (< 100 °C). For films deposition, argon (Ar: 200 sccm), acetylene (C₂H₂:10 sccm) and nitrogen (N: 5 sccm) were used as carrier, source and doping gases respectively. DLC:N thin films were deposited at 1000 W microwave power where as gas composition pressures were ranged from 110 Pa to 50 Pa. Analytical methods such as X-ray photoelectron spectroscopy (XPS), UV-visible spectroscopy, FTIR and Raman spectroscopy were employed to investigate the chemical, optical and structural properties of the DLC:N films respectively. The lowest optical gap of the film was found to be 1.6 eV at 50 Pa gas composition pressure.     

Effects of experimental parameters on the physical properties of non-stoichiometric sputtered vanadium nitrides films

Polycrystalline vanadium nitrides thin films were deposited onto (1 0 0)-oriented silicon wafers by reactive dc planar magnetron sputtering. The influence of the nitrogen gas flow (from 0 to 15 sccm) was studied. Several substrate temperatures were investigated: 150, 400 and 650 °C. Analytical techniques including X-ray diffraction and reflectivity, atomic force microscopy and optical photospectrometry were used to characterize the structure, the morphology and the optical properties of the films. The measured thickness indicates that the deposition rate is decreased (from 3.5 Å for 0 sccm to 1.5 Å for 15 sccm) with increasing nitrogen gas flow. Obtained structures depend on the substrate temperature. The structure of pure vanadium (0 sccm) varies from amorphous phase at 150 and 400 °C to -V phase at 650 °C. The films crystallize dominantly in β-V₂N_1−x phase at low nitrogen gas flows and in δ-VN_1−x phase at high nitrogen gas flows. The as-deposited VN films were highly textured. The texture seems to depend on the nitrogen gas flow. The root mean square (rms) derived from atomic force microscopy (AFM) varies with the nitrogen gas flow. The optical reflectivity of VN films shows high values in the infrared region.     

Structure and properties of Hf-O-N films prepared by high-rate reactive HiPIMS with smoothly controlled composition

Hafnium oxynitride ceramics were prepared in the form of thin films by high-power impulse magnetron sputtering of Hf in various Ar+O₂+N₂ gas mixtures. Smooth composition control was achieved by maximizing the degree of dissociation in plasma, suppressing the importance of the difference between reactivities of undissociated O₂ and N₂. The application potential of the films was further enhanced by extremely high deposition rates (e.g. 230 nm/min for stoichiometric HfO₂; achieved by feedback pulsed reactive gas flow control), low deposition temperatures (<140 °C) and not using any substrate bias. We focus on the relationships between elemental composition, phase structure, and optical, electrical, mechanical and hydrophobic properties of the materials. We quantify the evolution of smoothly controlled film properties along the transition from an oxide to a nitride, such as increasing extinction coefficient, decreasing electrical resistivity, increasing hardness or increasing water droplet contact angle.     

Influence of sputtering gas pressure on the LiCoO2 thin film cathode post-annealed at 400 °C

LiCoO₂ thin film cathodes were prepared by RF magnetron sputtering and post-annealing. The surface morphological change of the LiCoO₂ thin film wasin-situ measured by hot stage SEM with increasing temperature. The effects of sputtering gas pressure and post-annealing at low temperature (400 °C) were investigated by XRD, AFM, ICP-AES and RBS. The electrochemical characteristics of LiCoO₂ thin films were changed with variation of sputtering gas pressure. A difference of micro-structural evolution after post-annealing was observed, which related to the thin film properties. The electrochemical analysis revealed that the optimal sputtering gas pressure with the low temperature annealing step increases cell capacity and rate capability.