Sputtering Pressure Research Articles

Investigation of sputtering pressure on physical properties of CuO films and the electrical properties-temperature relationship of CuO films and p-CuO/n-GaN heterojunction

CuO had huge application prospects in the fields of semiconductor optoelectronic devices. However, the preparation of high-quality CuO films was still an urgent problem to be solved. Herein, we prepared CuO films at different sputtering pressures (0.6–2.1 Pa) by magnetron sputtering technology. The experiment results showed that the sputtering pressure had an obvious effect on the optical properties, structure, morphology and electrical properties of CuO films. It showed that relatively better CuO films could be prepared at 1.6 Pa. Moreover, Hall effect indicated that the change of ambient temperature had an obvious effect on the resistivity and carrier concentration of CuO films. Correspondingly, the p-CuO/n-GaN heterojunction device was fabricated, and the relationship between carrier transport characteristics and ambient temperature was studied. Ambient temperature had obvious influence on the turn-on voltage and rectification ratio of the device. This work provided a basis for the practical application of CuO-based optoelectronic devices.

Effects of sputtering pressure and oxygen partial pressure on amorphous Ga2O3 film-based solar-blind ultraviolet photodetectors

The coupling of Ga2O3 film with Si substrate is in favor of the development of high integration of Ga2O3-based UV photodetector. However, it is difficult in growing the high-quality crystalline Ga2O3 due to the high temperature and uncontrol growth process. In this work, the amorphous Ga2O3 (a-Ga2O3) films are deposited on Si substrates through tailoring the sputtering pressure and oxygen partial pressure to fabricate solar blind UV detectors. The results reveal that the high sputtering pressure and non-oxygen condition increase the oxygen vacancy concentration of a-Ga2O3 films. The existence of oxygen vacancy is beneficial to enhancing the internal gain of as-grown a-Ga2O3 films under UV light illumination. The UV photodetector based on the a-Ga2O3 film grown under 100 %Ar atmosphere at 20 mTorr exhibits high photodetection performances of responsivity, external quantum efficiency, and detectivity up to 2470 mA/W, 1204.7 %, and 2.55 × 1012 cm HZ1/2 W−1 under 254 nm @30 V, respectively. Alternatively, this UV photodetector hosts a rapid photo-response speed of rise time, τr and fall time, τd of 0.08 s and 0.157 s, respectively. This work offers a promising strategy to fabricate the a-Ga2O3-based solar blind UV detector with high photodetection performance, facile batch production and high integration with other electronics.

Microstructure and resistivity of Au-B supersaturated solid-solution films prepared by sputter deposition

• A series of Au–B films was deposited by magnetron sputtering. • Au-B supersaturated solid solutions without AuB 2 compounds confirmed in the films. • The microstructure of the Au–B supersaturated solid-solution films was studied. • The relationship between the resistivity and b content in the films was revealed. • The Au–B supersaturated solid-solution films were stable at room temperature. Au-B films are of interest for superconductor and hohlraums materials. A series of gold-boron (Au-B) films with different B contents has been deposited by magnetron sputtering of Au-B pseudo-alloy targets in an Ar atmosphere. The B atomic concentration of the Au-B films was varied by adjusting the B contents of the Au-B targets and sputtering pressure. The composition, microstructure and resistivity of the Au-B films were investigated by X-ray photoelectron spectrometry, X-ray diffraction and the four-probe method. Due to the mutually immiscibility of Au and B, non-equilibrium supersaturated solid solutions of B in Au with nanocrystalline microstructures instead of AuB 2 metal diboride were observed in the as-deposited films. With increasing B content, the average grain size of the films decreased and the d -spacing of Au (111) increased. The resistivity of the Au-B supersaturated solid-solution films was linearly related to the B content and no superconductivity was observed. The structure of the Au-B films was stable at room temperature for a long time, while annealing caused phase transition.

Improved frequency response of the 3.5 GHz SMR devices using Ga-doped AlN thin films as the piezoelectric layers

In this paper, the aluminum nitride (AlN) and gallium-doped aluminum nitride (AlGaN) films are adopted to fabricate the 3.5 GHz solidly mounted resonator (SMR) devices. A reactive radio frequency (RF) magnetron sputtering system and a co-puttering subsystem were used to deposit AlN and AlGaN thin films as piezoelectric layers. The sputtering parameters were fixed as sputtering pressure of 35 mTorr and sputtering power of 200 W for AlN piezoelectric layers. For the co-sputtering parameters, the sputtering pressure was set 10 mTorr, and the sputtering powers of Al and GaN targets were 175 W and 25 W, respectively, to deposit AlGaN piezoelectric layers. The X-ray diffraction (XRD) patterns showed that as compared with the 2[Formula: see text] values of the diffraction peaks of AlN thin films, those of AlGaN thin films shifted to lower values. Even the diffraction intensity of (002) peak of AlGaN thin film was higher than that of AlN film, both AlN and AlGaN thin films presented the strongly [Formula: see text]-axis orientated crystallization. The energy dispersive X-ray spectrometer (EDS) analysis showed that the content of Ga element in the AlGaN thin film, ([Formula: see text]), was about 19%. SEM images showed that the obtained AlN and AlGaN thin films exhibited uniform grain sizes and smooth surfaces. Finally, both the frequency responses of the fabricated SMR devices were measured using a network analyzer and the difference in their efficiencies were well compared. The frequency response of the fabricated SMR device with [Formula: see text][Formula: see text]N thin film showed the center frequency of 3.51 GHz, the return loss [Formula: see text] of −10.466 dB, quality factor [Formula: see text] of 170.952, electromechanical coupling coefficient [Formula: see text] of 4.026%, and FoM value of 6.838, respectively. The results show that the frequency response of SMR device has been improved by Ga doped in AlN thin film, although the [Formula: see text] value is still less than that of obtained using single crystalline AlGaN thin film.

Effect of Sputtering Pressure on the Nanostructure and Residual Stress of Thin-Film YSZ Electrolyte

Solid oxide fuel cells are energy conversion devices that contribute to carbon neutrality, with the advantages of high efficiency, clean emissions production, and distributed power generation. However, the high operating temperature of the solid oxide fuel cells causes system stability and material selection problems. In this study, we aimed to lower the operating temperature of a solid oxide fuel cell by reducing the thickness of the electrolyte via sputtering. The deposition process was conducted under various pressure conditions to find the optimal sputtering process for a gas-tight YSZ thin-film electrolyte. The gas-tightness of the YSZ electrolytes was evaluated by observing the nanostructure and cell performance. As a result, the YSZ thin-film deposited at 3 mTorr showed the best gas-tightness and cell performance. At 500 °C, 1.043 V of OCV and a maximum power density of 1593 mW/cm2 were observed. Then, X-ray diffraction was used to calculate the residual stress of the YSZ films. As a result, it was confirmed that the gas-tight film showed compressive residual stress. Through this study, we were successful in developing a room-temperature YSZ electrolyte fabrication process with excellent gas-tightness and performance. It was also proven that there is a strong relationship between the gas-tightness and residual stress. This study is expected to contribute to cost reductions and the mass production of solid oxide fuel cells.

Ballistic and thermalized regimes to tune structure and conducting properties of W–Mo thin films

W–Mo thin films are prepared by magnetron co-sputtering using glancing angle deposition. The same deposition angle αW = αMo = 80° is used for both W and Mo targets. Two different sputtering pressures are used: 0.33 Pa and 1.5 Pa, which correspond to ballistic and thermalized regimes of sputtered atoms, respectively. For each regime, W target current is kept at IW = 140 mA, whereas Mo target current gradually changes from IMo = 10–200 mA. Both regimes present porous thin films with inclined columns due to the shadowing effect that characterizes the films prepared with high oblique angle. Surface and cross-section morphologies exhibit elliptically bounded columns for the ballistic regime while they change to a cauliflower-like structure as thermalization prevails. At low pressure, the column angle β decreases with Mo target current and a Mo-enrichment of the films is noticed. Films are poorly crystallized at high pressure whatever the Mo target current with a high resistive behavior. The electrical resistivity vs. Mo content follows a rule of mixtures for films prepared at low pressure, whereas these deposited at high pressure correlate with a corrected Nordheim's law.

Reactive sputtered Ni-SDC cermet alloy anode for low-temperature solid oxide fuel cell

The facile deposition process for multi-component films is crucial in the development of thin film low-temperature solid oxide fuel cells (LT-SOFCs). Here, we report on the development and optimization of reactive sputtered Ni-SDC(Ni-Sm:CeO2) films for LT-SOFC anodes. The effects of oxygen partial pressure (PO2/PAr of 0 %–50 % at the sputter pressure of 30 mTorr) and deposition temperature on the physical, chemical and electrochemical properties of Ni-SDC films are studied. While the Ni-SDC anodes deposited at high PO2/PAr (>20 %) exhibited higher initial performance, they suffered from crack formation and massive Ni agglomeration upon operation due to NiO-to-Ni reduction and severe volume change. We further show that increasing the deposition temperature to 500 ℃ was effective in suppressing such Ni agglomeration and preserving the performance during operation.

Study on Deuterium Permeation Behavior of Palladium Films Prepared by Magnetron Sputtering Method

Pre-depositing a Pd film is crucial for accurately acquiring the hydrogen permeability of metal materials, as it permits the production of ultra-pure hydrogen. However, the microstructure of Pd film and its effect on the hydrogen isotope permeation behavior of substrate materials have been neglected. In this study, Pd films were deposited on China Low-activation Ferritic (CLF−1) steel by magnetron sputtering. The effect of sputtering pressure on the microstructure and deuterium permeation behavior of Pd films at temperatures of 550−650 °C is presented. SEM results demonstrated that the films had a columnar crystal structure with a thickness of 0.6 ± 0.2 μm. The gas-driven permeation results revealed that the deuterium ion current intensity of the coated CLF−1 sample was at least three times lower than that of uncoated CLF−1 steel, which was influenced by the combined effect of oxygen and surface cracks. Oxygen could not be excluded from the films at a sputtering pressure of 10−3 Pa order of magnitude. It was also found that the films cracked during deuterium permeation experiments, which affected the deuterium permeation behavior. Films with large surface coverage and small grain sizes exhibited better cracking resistance. Our study provides promising insights into the hydrogen permeability of Pd films.

Magnetron-sputtered gallium–magnesium–zinc oxide transparent semiconductor thin films: Structural, optical and electrical investigation

Thin transparent semiconductor films of gallium–magnesium–zinc oxide (GaMgZnO) have been prepared with magnetron-sputtering technique on quartz glass substrates. We have investigated the effects of sputtering pressure on the crystallization, micro-structure, electrical and optical features of the deposited films. The results indicated that all the deposited films were polycrystalline in nature having a hexagonal wurtzite-type crystal structure with a preferred grain orientation in the (002) direction. The sputtering pressure has a significant impact on the structure and electro-optical characteristics of the deposited films. The sample prepared under sputtering pressure of 3.6 Pa possesses the best crystalline quality and electro-optical performance, with the minimum dislocation density (3.69×1014linesm−2), tensile stress (8.26×107 Pa), resistivity (1.53×10−3Ωcm), the maximum mean visible transmittance (87.71%) and the highest figure of merit (4.73×103Ω−1cm−1). Additionally, the external extrapolation method is employed to evaluate the optical band gap. The gap value is between 3.41 and 3.44 eV, which is larger than the optical band gap of pure ZnO.

Fabrication of functional polyester fibers by sputter deposition with stainless steel

Abstract The effects of sputtering technological parameters (sputtering power, pressure, and time) on properties of stainless steel (SS)-sputtered polyester (PET) fiber were investigated. The variations in properties such as surface morphology, tensile strength, abrasion resistance, and electromagnetic shielding effectiveness of the prepared PET fiber sputtered under various parameters were discussed. The results indicated that the uniformity and denseness of the sputtered SS film were positively dependent upon the predetermined sputtering variables. The properties such as the breaking strength and abrasion resistance of SS-sputtered PET were remarkably enhanced as compared to the pristine one. It was found that the disorientation of macromolecules in fiber was mainly responsible for the deteriorated strength following wet and/or dry heating. In addition, a woven fabric composed of SS-sputtered fiber exhibited electromagnetic shielding capability. This research indicates that the metal deposition onto textile surfaces using magnetron sputtering is a straightforward approach for potential use in multifunctional materials.

Influence of ZnO Film Deposition Parameters on Piezoelectric Properties and Film-to-Substrate Adhesion on a GH4169 Superalloy Steel Substrate.

ZnO film is widely used in the field of health monitoring sensors, which has high requirements for the piezoelectric coefficient and film-to-substrate adhesion of the ZnO film. In this study, ZnO thin films were grown on a GH4169 superalloy steel (GSS) substrate using magnetron sputtering, and the effects of the sputtering power, argon–oxygen ratio, and sputtering pressure on the piezoelectric coefficient and film-to-substrate adhesion were studied. The composition, microstructure, and crystal orientation of ZnO thin films deposited under different process parameters were analyzed using X-ray diffraction (XRD), a scanning electron microscope (SEM), and an energy spectrum analyzer (EDS). The piezoelectric coefficient d33 was measured using a piezoelectric coefficient measuring instrument. The critical value of adhesion between the film and substrate was measured using the scratch method. The results demonstrated that the ZnO films had the most desirable properties when the sputtering power was 150 W, the argon–oxygen ratio was 25:10, and the sputtering pressure was 0.7 Pa. The XRD results showed that the ZnO film samples had the strongest (002) crystal orientation at 2θ = 34.4°; the SEM photos showed that the film samples were flat and uniform; and the EDS composition analysis results showed that the composition was close to the theoretical value. The maximum d33 coefficient value was 5.12 pC/N, and the maximum value of film-to-substrate adhesion between the ZnO films and GSS substrate was 4220 mN.

Photoexcitation and radiation regulation mechanism of Ag anchoring WSe2 heterojunction with plasma coupling effect

The noble metal silver (Ag) combined with tungsten selenide (WSe2) was used to solve the problems of the narrow absorption band range, low luminescence quantum yield, and nonlinear transmittance of WSe2 base materials. Ag/WSe2 films and core–shell Ag@WSe2 heterojunction were designed and fabricated by the two-step magnetron sputtering and hydrothermal/magnetron sputtering method, respectively. X-ray diffraction, scanning electron microscopy and X-ray photoelectric spectroscopy results confirmed that the successful preparation of Ag/WSe2 and Ag@WSe2. Raman results demonstrate the presence of interfacial stress between Ag and WSe2. Based on quantum particle coupling in metal–semiconductor nanocomposites, the adsorbed silver particles provide electrons and through charge transfer, which increases the density of electronic states in conduction band of the WSe2 and thus increases the spontaneous emission rate. Electron-hole pairs generated in the semiconductor through resonant coupling between surface plasmas of the Ag and WSe2 interface will provide strongly enhanced radiative recombination. The absorption and emission of WSe2 nanosheets in the visible light range and linear-nonlinear optical properties depend on the regulation the sputtering power and pressure of Ag particles. Our research results demonstrate that Ag&WSe2 have excellent optical and photoelectric properties, indicating that Ag&WSe2 have a wide application potential in photoelectric functional and optoelectronic devices.

Deposition of nanoporous BiVO4 thin-film photocatalyst by reactive magnetron sputtering: Effect of total pressure and substrate

Nanoporous BiVO4 thin films were deposited using reactive magnetron sputtering in Ar and O2 atmosphere, on various substrates, employing pulsed direct-current (DC) power supplies applied to metallic Bi and V targets for rapid deposition. The procedure was followed by a post-annealing treatment in air to crystallize the photoactive monoclinic scheelite structure. The influence of total pressure and substrate on the crystal structure, morphology, microstructure, optical and photocatalytic properties of the films was investigated. The crystallization of monoclinic scheelite structure deposited on fused silica substrate starts at 250 °C and the films are stable up to 600 °C. The morphology of the films is rather dense, despite at the high sputtering pressure (>2 Pa), with embedded nanopores. Among the thin films deposited on fused silica, the one deposited at 4.5 Pa exhibits the highest porosity (52%), with the lowest bandgap (2.44 eV) and it shows the highest photocatalytic activity in the degradation of Rhodamine-B (26% after 7 h) under visible light irradiation. The film deposited on the silicon substrate exhibits the highest photoactivity (53% after 7 h). Lack of hypsochromic shift in the UV−Vis temporal absorption spectra shows the dominance of the chromophore cleavage pathway in the photodecomposition.

Oblique angle co-deposition of nanocolumnar tungsten thin films with two W sources: Effect of pressure and target current

Two series of tungsten thin films are sputtered on silicon and glass substrates by oblique angle co-deposition technique with an original configuration. Two opposite distinct tungsten targets are simultaneously used, both tilted with an oblique angle of 80°. The growth is performed at low (0.33 Pa) and high (1.5 Pa) argon sputtering pressure and the current intensity applied to the targets varies between 50 and 250 mA. The effect of these deposition parameters on the films microstructure and electrical properties is investigated by scanning and transmission electron microscopy, X-ray diffraction and pole figures, and van der Pauw method. Due to self-shadowing effect, all tungsten sputtered thin films are porous and columnar. At low pressure, the columnar tilt angle β can be tuned with the target current intensity until obtaining vertical columns. X-ray diffraction and pole figure analyses point out a A15 crystal structure (β-W) and a uniaxial fiber texture with a <100> growth direction. In contrast, tungsten thin films deposited at high pressure present a cauliflower structure and are poorly crystallized. Both deposition parameters also affect the films electrical resistivity and anisotropy. These behaviors are discussed and linked to the microstructure and crystallography.

High reflectivity Co/Mg multilayer working in the broad soft x-ray range of 350–770 eV

A Co/Mg multilayer was proposed and optimized to work in the broad soft x-ray range of 350–770 eV. The multilayers with a d-spacing of 6.0 nm showed large interface widths of 1.95–1.07 nm which were significantly improved to 0.65–0.62 nm by using a higher Co sputtering power. Grazing incidence x-ray reflectometry, atomic force microscopy, transmission electron microscopy and x-ray diffraction measurements were used to study the multilayer structure and a more ordered polycrystalline structure was found in the multilayers deposited with higher Co power, which can explain the great improvement. The effect of Ar sputtering pressure on the layer structure was also studied. The measured soft x-ray reflectivity results indicated a high reflectivity of 18%–27.5% at 400–700 eV can be reached if a saturated number of bilayers of 50 were deposited.

Dependence of the sputtering pressure on the characteristics of sputtered ZnO:Al thin films

Dependence of the sputtering pressure on the characteristics of sputtered ZnO:Al thin films

Impedance spectroscopy analysis of Al/100-plane AlN/p-Si MIS prepared by HiPIMS method for tailoring dielectric properties

The effects of variation of sputtering pressure of AlN HiPIMS deposition on Si substrate to the structure and electrical properties were investigated through XRD, AFM and impedance spectroscopy method. The strong preferred 100-plane AlN was observed for all samples from XRD pattern. The AlN thin film thickness was observed decrease with the increase of sputtering pressure. AFM analysis shows the lowest surface roughness at 0.84 nm for 5 mTorr sputtering pressure. Impedance spectroscopy analysis of Al/100-plane AlN/Si MIS structure shows the electrical conductivity of AlN was directly proportional to the sputtering pressure and stable with temperature ranging from room temperature (299 K) to 353 K. Good dielectric stability was achieved at 3 mTorr sputtering pressure for all variation temperature and the dielectric constant calculated at average 3.5.

Structural, optical and electrical properties of CuO nanostructures prepared by reactive DC magnetron sputtering

An attempt is made to explore the CuO nanostructures and their attributes in this work. CuO nanostructures are deposited on glass substrates using DC reactive magnetron sputtering using Cu target in argon (84%) and oxygen (16%) environment. These nanostructures are deposited at sputtering power of 70 W, different sputtering pressures in the range 1.0–8.0 Pa and deposition time of 10–60 min. X-ray diffraction (XRD) technique is used to determine the oxide phase of the deposited nanostructures. The XRD pattern matches CuO standard diffraction data (ICDD file 00-005-0661), confirming that no additional oxide phases appeared in the nanostructure coated for different deposition time at higher pressure. Due to the very low content of CuO, no peaks attributable to CuO are observed in the nanostructures deposited for 10 min at sputtering pressure of 3.0–8.0 Pa. In the nanostructure deposited at 1.0 Pa, a new phase Cu2O has evolved. The nanostructure deposited for 60 min has a crystallite size of 26 nm. Field emission scanning electron microscopy (FESEM) is used to analyse the morphologies of the nanostructures. Isolated nanograins of CuO are observed in nanostructures that have been deposited for 10 min, when the deposition time is extended to 40 and 60 min, an almost film-like structure is formed. Sputtering pressure of 8.0 Pa produces highly isolated nanograins; lowering the pressure results in less isolated nanograins. UV–Visible absorption spectroscopy is utilized for optical studies. Transmittance and absorbance spectra are recorded in the 200–1100 nm wavelength range. The nanostructures absorb light strongly in the 280–400 nm region and it is observed that decrease in the sputtering pressure (from 8.0 Pa to 1.0 Pa) and higher deposition time enhance the absorption capacity in this range (280–400 nm) as well as in the visible range. The nanostructures have transmittance of more than 80% in the wavelength range 780–1100 nm. The sheet resistance of the nanostructures is estimated to be between 10.3 and 25.0 kΩ/sq. Hall measurement confirms p-type conductivity of CuO nanostructures and carrier concentration reaches the order of 1018 cm−3.

Technique of TiNi-based shape memory alloy thin film coating on optical fibers

&lt;sec&gt;Intelligent, integrated and cost-effective micro-electro-mechanical system (MEMS) and micro sensors can be developed with TiNi-based memory alloy thin film and optical fibers. Such devices can work in harsh environment, like in deep sea, in space with flammable or explosive objects, or with strong electromagnetic interference; and examples of their possible applications include gas concentration detection in underground mines, dynamic detection of production parameters in oil or gas mining, etc. As TiNi-based memory alloy thin film possesses good biocompatibility, such devices can also be used in intracranial/endocardial pressure test, surgical resection, early cancer assessment, etc. The successful development of the above MEMS and micro sensors involve optical fibers coated with memory alloy films. However, unlike the common planar substrates, optical fiber is of a cylinder with a small diameter, and how to grow good-quality memory alloy film on its surface remains to be explored.&lt;/sec&gt;&lt;sec&gt;In this work, the silica fibers are coated with TiNi memory alloy films by magnetron sputtering. How to choose the proper operating parameters in the sputtering process, and also the effects of subsequent annealing treatment on the films, are discussed in detail. Uniform thin films are grown on the 125-μm-diameter cylindrical surfaces of optical fibers with our built coating mask device specially designed for fibers. The experiments show that when target-substrate distance, background vacuum degree, Ar gas flow and sputtering time are fixed in the sputtering process, the sputtering power can be optimized, while a higher sputtering pressure results in lower film deposition rate but better surface roughness. The thin film is well crystallized under annealing, and the major martensite B19′ phase and minor austenite B2 phase coexist in the Ti&lt;sub&gt;49.09&lt;/sub&gt;Ni&lt;sub&gt;50.91&lt;/sub&gt; film. In the experiments, with the optimal operating parameters (sputtering power of 150 W and sputtering pressure of 0.23 Pa), TiNi memory alloy film about 852.2 nm in thickness is grown on the fiber at a deposition rate of 0.118 nm/s, and surface root mean square roughness of the unannealed film is 15.1 nm. Annealing at temperatures of 500, 550 and 600 ℃ are respectively tried, and such a thermal treatment evidently refines the crystalline grains inside the film. Surface root mean square roughness of the film annealed at 600 ℃ is reduced to 6.32 nm.&lt;/sec&gt;&lt;sec&gt;This work indicates that a glass fiber can be coated with high-quality TiNi-based memory alloy film, and it thus forms a part of the bases of further development of relevant MEMS and micro sensors.&lt;/sec&gt;

Analysis of Physical, Ocular, and Aquaphobic Properties of Zirconium Oxide Nanofilms by Varying Sputtering Pressure

A thin coating of zirconium oxide (ZrO2) is placed on outdoor high‐voltage insulators to minimize air fouling. ZrO2 thin film coatings were deposited on glass substrates using a DC sputtering (reactive magnetron) technique with sputtering pressures ranging from 5 to 25 mTorr. Characterization of the deposited films was carried out utilizing approaches such as XRD, AFM, CAG, and spectrophotometer. Following the XRD peaks, when 15 mTorr is reached, the average crystallite size increases, after which it begins to decline. The wettability of the deposited thin layer is associated with the coarseness calculated by AFM. At 15 mTorr pressure, maximum aquaphobic is achieved (107.45°). At this pressure, the transmittance and bandgap were similarly determined to be 90% and 5.43 eV, respectively.