DC Sputtering Research Articles

Correlation of sputtering power with microstructure and ionic conductivity in lithium aluminum oxide thin films prepared by reactive co-sputtering

Li–Al–O thin films synthesized via the reactive magnetron co-sputtering have the potential to act as solid-state electrolytes in micro-batteries. In this paper, the constant RF power (155 W) and variable DC power (20–50 W) were applied to lithium (Li) and aluminum (Al) metal targets, respectively, in Ar/O2 atmosphere to produce films with adequate ionic conductivity. The influence of DC sputtering power on the composition, microstructure, band gap energy, ionic conductivity, and dielectric loss of films were studied in detail. X-ray photoelectron spectroscopy (XPS) showed a shift of the Li 1s peak towards higher binding energy with increasing DC power. X-ray diffraction (XRD) spectra confirmed the amorphous state for all as-deposited films, while the post-annealed films at 950 °C contain the γ-LiAlO2 phase. Field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM) images revealed that the increasing DC power had a significant impact on the film morphology, enlarging grain size and increasing surface roughness. Energy dispersive X-ray (EDX) spectroscopy showed that increasing the DC power increased the Al content. The optical properties were examined by ultraviolet–visible (UV–vis) spectroscopy, which indicated that increasing the Al content led to a blue shift of the absorption edge and an increase in the band gap energy (5.40–5.68 eV). Increasing the DC power resulted in an improvement of room-temperature conductivity by two orders of magnitude (∼2.85 × 10−9 S cm−1) and a decrease in the activation energy from 0.54 eV to 0.32 eV. These results suggest that composition and microstructure significantly affect the ionic transport in co-sputtered Li–Al–O films.

IoT-enabled surface-active Pd-anchored metal oxide chemiresistor for H2S gas detection

The Internet of Things (IoT) has a crucial role in advancing various fields such as Industry 4.0, Big Data, and Machine-to-Machine technologies. All systems continuously gather information on various parameters such as temperature, speed, pressure, health data, environmental conditions, and consumption. Considering this, we've developed a novel fabrication method for H2S gas sensor prototypes. These sensors are based on noble metal-functionalized on metal oxide semiconductor (MOS) chemiresistors. The fabrication process involved growing CuCrO2 sensing thin film on SiO2/Si substrates using the RF sputtering method. Subsequently, Pd nanoparticles, known for their excellent gas-sensing catalyst properties, were functionalized onto the CuCrO2 films using DC sputtering with varying sputtering times of 3, 6, 9, and 12 s. Nanorice morphology boosts gas absorption, capturing more target molecules. A 9 s Pd sputtering time greatly improved H2S sensing over other gases. CuCrO2 film with Pd showed the highest 72.3% response to 50 ppm H2S, detecting down to 0.5 ppm. These results were achieved at the optimal working temperature of 150 °C. After optimizing parameters, we transferred the technology to develop a sensor module for the prototype with IoT integration. The prototype sensor connects to NODEMCU-ESP8266 Wi-Fi, which links to a smartphone through a mobile hotspot.

Hydrogen gas sensor based on SnS nanoparticles prepared by a DC sputter process

Hydrogen gas sensor based on SnS nanoparticles prepared by a DC sputter process

Intensity modulation of UV light in gas sensor array to discriminate several analytes at room temperature

AbstractIn this study, a gas sensor array along with intensity modulation of UV light was utilized to discriminate several gases at room temperature. The sensor array was consisted of two interdigitated microelectrodes and TiO2 nanofibres were electrospun on them and calcined at 540°C for 90 min. One of these sensors was coated by 2‐nm Pt using the DC sputtering method and the other one remained uncoated. In each experiment, the sensor array was located at a distance of 30 mm from a 365‐nm UV LED. For intensity modulation of UV light, a staircase waveform voltage was applied to the UV LED. The voltage was included of three voltage steps and the measured powers at a distance of 30 mm from the UV‐LED were about 450, 560, and 680 µW/cm2, respectively. Analytes including acetone, ethanol, methanol, 2‐propanol, and carbon monoxide (CO) at various concentrations ranging from 50 to 500 ppm were examined. Three‐dimensional Principal Component Analysis mapping was successfully used for the segregation of all examined gases. The examinations revealed that using sensor array along with intensity modulation of UV light is an effective method for discrimination of several analytes at room temperature.

Fabrications of metal-insulator nanocomposite TiOx thin films and their dielectric properties

The nanocomposite titanium oxides (TiOX) films were grown on the glass substrate using the reactive DC sputtering method. A solid-state disproportionation process led to the development of a multi-phase structure, consisting of nanocrystalline dioxies (TiO2) and suboxides (TinO2n-1) embedded with an amorphous TiO2-δ matrix. As the plasma discharge impedance decreased during the sputtering growth, a sequence of TiO2 crystallites, sesquioxides (Ti2O3), and eventually monoxides (TiO) were formed. This progression came at the expense of compromising the quality of the TiO2 crystallites and resulted in the reduction of oxygen vacancies in the a-TiO2-δ matrix. Furthermore, the frequency-dependent impedance measurements revealed that the metal-insulator nanocomposite TiOx films containing TiO crystallites exhibited a remarkable permittivity above 106 in the frequency range of 102 ∼106 Hz. We believe that the observed colossal permittivity is primarily attributed to the interface polarization within the composite constituents, in addition to the electrode effects.

Ellipsometric Study on the Uniformity of Al:ZnO Thin Films Deposited Using DC Sputtering at Room Temperature over Large Areas.

Al-doped ZnO combines high transparency and conductivity with abundant and non-toxic elements; making it suitable for optoelectronic devices with large-scale applications. In order to check the quality of the material deposited over large areas, spectroscopic ellipsometry is a powerful technique that allows the determination of various optical and electrical parameters by applying suitable oscillator models. This technique is used here to obtain sheet resistance and visible transmittance data at several equidistant points of Al:ZnO thin films deposited using DC sputtering on 15 cm × 15 cm glass substrates. Independent measurements using other optical (spectrophotometry) and electrical (four point probe) methods show analogous visible transmittance but somewhat higher resistance values than those obtained with ellipsometry, which is explained by the contribution of grain-boundary scattering compared to in-grain properties provided using ellipsometry. However, the mapping of the data gives a similar spatial distribution to the different types of measurement; therefore, proving the capacity of ellipsometry to study with a single tool the uniformity of the optical and electrical characteristics of large areas.

The effect of solid solution treatment with coating on corrosion properties of AZ91 Mg alloy in simulated body fluid

The current study involves an attempt to reduce the corrosion rate of AZ91 Mg alloy that is used in biomedical applications, where it is known as biodegradable material and needs to increase its lifetime until healing can occur. Firstly, solid solution treatment at 450 °C for 8 hr. was worked to reduce the second phase represented by Mg17Al12 and then reduce the galvanic cells on the alloy’s surface. Secondly, coating with indium and titanium metals was done by DC sputtering. The characterization of treated and treated/coated specimens was accomplished by XRD, SEM/EDS, and AFM confirming the improvement of solid solution treated/In coated alloy surface compared with the treated uncoated and solid solution treated/Ti coated alloy. Corrosion properties were investigated by potentiostatic measurement indicating that the solid solution treated/In coated alloy gave lower corrosion current density (i.e., lower corrosion rate), protection efficiency equal to 38.31%, polarization resistance increased from 33.482 × 102 to 36.876 × 102 Ω.cm2 and lower porosity compared with coated specimen by Ti. The reason for this improvement comes from the full coverage of the surface by a compact regular layer of indium as well as the formation of the Mg3In phase. The porosity percentage PP% showed the high porosity for treated/Ti coated specimen which reached to 2104.1%.

A Palladium-Deposited Molybdenum Disulfide-Based Hydrogen Sensor at Room Temperature

Recently, hydrogen (H2) energy has attracted attention among eco-friendly energy sources because H2 energy is eco-friendly, energy-efficient, and abundant in nature. However, when the concentration of H2 in the atmosphere is more than 4%, H2 has a risk of explosion. H2 is a colorless, tasteless, and odorless gas that is difficult to detect with human senses. Therefore, developing an optimized hydrogen sensor is essential. Palladium (Pd) has good reactivity to hydrogen. Molybdenum disulfide (MoS2) has high carrier mobility, sensitive reactivity to toxic gases, and high surface-area-to-volume ratio. Therefore, we proposed hydrogen sensors that use Pd and MoS2. The main fabrication processes include MoS2 deposition through CVD and Pd deposition through DC sputtering. In this study, we utilized Pd and MoS2 to enable sensing at room temperature. By optimizing the Pd to a nanoparticle structure with an expansive surface area of 4 nm, we achieved a fast response time of 4–5 s and an enhanced yield through a simplified structure. Hydrogen sensors inherently exhibit sensitivity to various environmental factors. To address these challenges, technologies such as machine learning can be incorporated. Emphasizing low-power consumption and various application compatibilities becomes pivotal to promoting commercialization across diverse industries.

Low-temperature detection of acetone gas using ZnO-TiO2 nanorod on tapered multimode fiber decorated with Au-Pd thin films

This paper presents the influence of titanium dioxide (TiO2) as a catalyst to the zinc oxide (ZnO) nanorods coated on the tapered MMF fiber utilized as a sensing layer for the detection of acetone gas at low temperatures. To enhance the sensitivity of the sensor ZnO-TiO2 nanorods were decorated with Au-Pd film. Hydrothermal method was used to synthesize the ZnO nanorods while TiO2 powder was incorporated by using a simple doping procedure during fabrication. The decoration of the Au-Pd thin films is integrated with the ZnO-TiO2 by using DC sputtering method. The ZnO doped with 15 mM TiO2 shows a strong and significant peak based on XRD analysis which can be indexed to the hexagonal phase of ZnO. A few globular structures of TiO2 were randomly distributed as observed by the SEM image. Four different fiber sensing layers were prepared with respect to 10 mM ZnO precursor; ZnO nanorods (ZN), ZnO nanorods decorated with Au-Pd thin films (ZNAP), ZnO-15 mM TiO2 nanorods (ZTN) and ZnO-15 mM TiO2 nanorods decorated with Au-Pd thin films (ZTNAP). The spectrometry setup was used to measure the response of the sensor toward different concentrations of acetone gas in terms of intensity with respect to its wavelength. Notable output intensity responses were observed for ZTNAP in terms of sensitivity and standard deviation towards various acetone concentrations while the repeatability curve showed a high response of acetone gas at 10,000 ppm. All experiments were performed at the low temperature of 87 °C.

DC Saçtırma Metoduyla Üretilmiş Çift Katmanlı Mo İnce Filmlerin Yarı Kantitatif Doku Analizinin Yapılması ve Kutup Figürlerinin Araştırılması

Molibden (Mo) malzemesi benzersiz özellikleri sayesinde birçok farklı alanda kullanılmaktadır. İnce filmlerin doku analizleri sayesinde katmanlar arası arayüz durumlarının uyumluluğu araştırılmaktadır. Üretim parametrelerine ve sonrasında yapılan işlemlere göre filmlerin dokuları değişebilmektedir. Bu sebeple kullanım alanına bağlı olarak en uygun dokuya sahip Mo ince filmlerin üretilmesi için ideal üretim parametrelerinin belirlenmesi gerekmektedir. Bu çalışmada, CIGS güneş gözesi uygulamalarında sıklıkla istenen BCC yapısında ve (110) düzlemindeki Mo ince filmler üretilebilmiştir. Üretim, Mo filmin alttaş yüzeyine tutunumunu ve elektriksel iletkenliğini iyileştirmek için çift katmanlı üretim stratejisi kullanılarak gerçekleştirilmiştir. Üretilen filmlerin SEM, AFM ve XRD sistemleri ile yüzey, topoğrafya ve yapı analizleri gerçekleştirilmiş ayrıca yarı kantitatif doku analizleri yapılarak kutup figürleri elde edilmiştir. Topoğrafik ve detaylı yapısal analiz sonuçları birbirleri ile ve literatürde var olan diğer çalışmalar ile kıyaslandığında bu çalışmada ortaya koyulan üretim parametrelerinin kullanılabilirliği gösterilmiştir.

Influence of sputter pressure on magnetic and structural properties of Permalloy thin films

Well-defined and technically relevant domain configurations are sought in patterned magnetic thin films. We used Magnetic Force Microscopy to investigate these in square-patterned Permalloy films. The films were prepared using dc sputter deposition by varying the Argon pressure from 1.5×10−3 to 30.0×10−3 mbar. The Landau domain configuration was found in films prepared at 1.5×10−3 mbar pressure. With an increase in pressure, tulip and irregular domains were consecutively formed. Based on magnetic and structural characterizations, an increase in coercivity and a decrease in Permalloy film density were observed at the same time.

Optical behavior and electrical conductivity of ferromagnetic nanostructured Co:Fe thin films

Recently, there has been an increasing interest in optical applications of nanostructured metal thin films based on transparent conductive layers. There is little data published on the study of the optical behavior of ferromagnetic materials such as Co:Fe alloy thin films. DC sputtering technique was used to grow the magnetic crystalline Co:Fe thin films, on glass substrates, in different nano-thicknesses in range of 20, 35, 50, 75 and 100[Formula: see text]nm. XRD technique, atomic force microscopy (AFM), and a spectrophotometer of Ultraviolet–visible (UV–Vis) were used to analyze the films. The XRD data confirmed that the samples of Co:Fe films showed out-of-plane direction of [Formula: see text]. The data indicates that an increase in the average grain size and lattice constant of the films is presented related to increase in the nano-thickness of Co:Fe alloy thin films samples. From AFM, it is illustrated that the roughness of the film is about ([Formula: see text][Formula: see text]nm) which is due to the produced grains. The optical response, optical conductivity and electrical conductivity have been affected by the changed nano-thickness of the metallic Co:Fe thin films.

The Role of Reactive Gas Pulsing Synchronized with Digitally Processed DC Sputtering

The Role of Reactive Gas Pulsing Synchronized with Digitally Processed DC Sputtering

Gas sensing performance of Tungsten doped V2O5 nanorod thin-films deposited by hot filament CVD combined with DC sputtering

High-quality polycrystalline tungsten doped vanadium pentoxide thin-films were prepared using Hot Filament Chemical Vapor Deposition technique (HFCVD) combined with sputtering by changing target to substrate distance and reaction duration. Scanning electron microscopy and X-ray diffraction revealed that the morphologies and crystalline structures of the films are depending on the deposition parameters such as target to substrate distance and deposition time. Raman spectroscopy is also used to analyse the oxidation states of the vanadium-based films. The deposited nanorod thin-film was exposed to ammonia and ethanol gases to test their gas sensing performance. It exhibits a sensing response of 1.8 and 1.65 at a concentration of 200 ppm ammonia and ethanol and has a recovery time of 44 and 31 s, respectively.

STRUCTURAL AND MECHANICAL CHARACTERIZATION OF TUNGSTEN NITRIDE COATINGS PREPARED BY DC SPUTTERING AT CYLINDER LINER

The cylinder liner is a tube that protects the piston and is a place for the combustion process. The combustion process causes continuous friction to make the cylinder liner wear out. Therefore the cylinder liner must be made of materials that have high hardness. To obtain a high hardness level, surface treatment with DC sputtering techniques is carried out. Surface treatment with DC sputtering technique for 120 minutes with variations of Argon gas and Nitrogen gas 70:30, 80:20, and 90:10. Based on the XRD test results, all treated samples contained a WN layer. The crystal structure of the raw material samples is hexagonal, and the crystal structure of all processed samples is cubic. Vickers hardness characterization shows that the raw material is 110.93 HV. While the sample treated with Ar70:N30 was 234.66 HV. The optimum hardness occurred in samples treated with Ar80:N20 with a hardness of 311.87 HV. However, the Ar90:N10 treatment experienced a decrease in hardness to 130.44 HV. Based on the results of thin film testing, WN affects the increase in the hardness of the cylinder liner material. This is evidenced by the increase in hardness in samples coated with WN.

Synthesis and H2S Gas-Sensing Properties of SnO2/ZnO Core/Shell Structure

In the study, SnO2/ZnO core/shell nanowires were synthesized through the two-step processes. First, SnO2-core nanowires were synthesized from Sn powder source at 750 oC by a chemical vapor deposition method (CVD). The ZnO shell was then deposited on SnO2 nanowires by a DC sputtering method. The morphological and crystal structures of the grown SnO2/ZnO core/shell nanostructures were investigated by emission scanning electron microscopy (SEM), field-emission scanning electron microscopy (FESEM), and X-ray diffraction (XRD). The results indicated a successful synthesis of the SnO2/ZnO core/shell nanowires with the thickness of the ZnO shell ranging from 5 nm, 10 nm, and 15 nm. The H2S gas sensing properties of the SnO2/ZnO core/shell structure sensors were then investigated, and results pointed out that the sample with a shell thickness of 10 nm showed an effective response and recovery to H2S gas in the concentration range 0.25 ppm - 2.5 ppm at the temperature range of 300 oC, 350 oC, 400 oC. The optimal working temperature of the sensor was found at 350 oC, where the sensor has a response of 7.8 towards 2.5 ppm. The selectivity of the sensor at 350 oC was also studied. These findings suggest that the sensor could have potential applications in detecting traces of H2S gas in the medical, food, and environmental fields.

Structural, optical and electrical properties of ZnO–InN quaternary compound films

The ZnO–InN compound films were fabricated via both RF and DC sputtering by using indium and zinc metal target, where N2O and N2 gases were employed as the sputtering gas. The optical band gap was continuously tuned from 1.9 to 3.4 eV by precisely tailoring the chemical composition of the compound film. Both optical band gap and lattice spacing can be described by Vegard rule well. The carrier density can be adjusted up to 6.20 × 1020 cm−3 by varying the chemical composition of ZnO–InN compound. When the carrier density exceeds ∼1020 cm−3, the ZnO–InN compound films show the characteristics of degenerated semiconductor. Our experiments also reveal that the grain boundary scattering dominates carrier transport for ZnO–InN compound films with carrier density below 1020 cm−3.

Nonenzymatic Glucose Sensors of ZnO Nanorods Modified by Au Nanoparticles

In the article, the non-enzymatic glucose sensor Au nanoparticles (NPs) adsorbed on ZnO nanorods (NRs) was synthesized onto glass substrate by the hydrothermal method, and Au NPs were deposited on the surface of ZnO NRs via DC sputter system. The morphologies and crystal structures of ZnO and Au/ZnO NRs were investigated by field-emission scanning electron microscopy, transmission electron microscopy and X-ray diffraction. The Au NPs adsorbed on the ZnO NR (Au/ZnO) electrode exhibited excellent sensitivity and selectivity for glucose detection. Under an applied bias of 0.2V, the sensitivity of ZnO and Au/ZnO NRs electrodes were 63.4 and 182.96 μA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ∙mM for linear range at 0 to 8 mM. In the interference detective section, the electrodes of ZnO and Au/ZnO NRs exhibited excellent selectivity for glucose detection when the test solutions contain various interfering species, such as ascorbic acid and uric acid. It is demonstrated that the non-enzymatic glucose sensor of the Au/ZnO NR electrode is suitable for glucose detection in human blood samples.

Physical Properties of SnO2/WO3 Bilayers Prepared by Reactive DC Sputtering

The combination of transparent and conductive SnO2 with colored WO3 thin films has interesting uses in electrochromic windows, photovoltaic cells and photocatalytic systems, where the SnO2/WO3 bilayer can improve the device efficiency by increasing the charge separation and extending the energy range of photoexcitation. In this work, SnO2 and WO3 thin films were prepared by reactive DC sputtering from Sn and W targets, respectively. Single layers and bilayers deposited on glass substrates have been analyzed by X-ray diffraction, atomic force microscopy, spectrophotometry, and electrical measurements. SnO2 crystallizes in the cassiterite structure, whereas amorphous WO3 is obtained on bare and SnO2-coated glasses, showing higher surface roughness on the SnO2 layer. Different oxygen vacancy defects have been identified in WO3 by analyzing photoconductivity transients. The oxygen vacancy defects are responsible for the sub-bandgap absorption that causes coloration in the WO3 films. Regarding SnO2, it shows a high transmittance of about 90% in the visible and near-infrared spectral ranges.

Structural characteristics and sensing capabilities of stacked Ti/Ni sensitive film for extended-gate field-effect transistor solid-state pH sensors

This study describes a straightforward approach for fabricating stacked Ti/Ni sensitive membranes on n+-type Si substrates using dc sputtering to build solid-state extended-gate field-effect transistor (EGFET) pH sensors. The effects of rapid thermal annealing (RTA) temperature (500–700 °C) and ambient (N2 or O2) on the structural characteristics of stacked Ti/Ni sensitive films were fully explored. We used X-ray photoelectron spectroscopy, secondary ion mass spectroscopy, X-ray diffraction, atomic force microscopy, transmission electron microscopy, and energy dispersive X-ray spectroscopy to characterize the chemical compositions, element profiles, film structures, surface morphologies, film microstructures, and film compositions of the stacked Ti/Ni sensitive films. The relative structural characteristics of the stacked Ti/Ni sensitive films have a significant impact on their sensing capabilities. The most effective sensing performance, such as pH sensitivity, drift, and hysteresis, was achieved at an RTA temperature of 600 °C and in the presence of N2 gas among various RTA temperatures and annealing ambient. Due to its compact size and strong stability, the stacked Ti/Ni sensitive film shows great potential for use in future pH sensor and biosensor applications.