Reactive RF Magnetron Sputtering Technique Research Articles

Performance optimization of AlN ultrasonic thin-film sensors deposited by RF magnetron sputtering

The AlN thin-film ultrasonic transducers were deposited by reactive RF magnetron sputtering technique. The effects of deposition parameters: target-substrate distance, argon-nitrogen flow ratio, deposition time, substrate temperature and radial distance from the deposition center on the ultrasonic performance of AlN thin films were studied. A metal electrode layer was deposited on the AlN film transducer to fabricate an ultrasonic temperature sensor, and the effects of the size and thickness of the electrode layer on the performance of the sensor were studied. Piezoelectric response measurements were performed in air over a temperature range of −60 °C–900 °C, and the dependence of ultrasonic response (time-of-flight and pulse echo amplitude) on temperature was analyzed. Long-term heat treatment in air at 750 °C for 128 h showed that the high-entropy alloy oxide protective layer could effectively delay oxidation of the AlN layer and improve the service life of the sensor.

Acoustoelectric Effect due to an In-Depth Inhomogeneous Conductivity Change in ZnO/Fused Silica Substrates

The acoustoelectric (AE) effect induced by the absorption of ultraviolet (UV) light at 365 nm in piezoelectric ZnO films was theoretically and experimentally studied. c-ZnO films 4.0 µm thick were grown by the RF reactive magnetron sputtering technique onto fused silica substrates at 200 °C. A surface acoustic wave (SAW) delay line was fabricated with two split-finger Al interdigital transducers (IDTs) photolithographically implemented onto the ZnO-free surface to excite and reveal the propagation of the fundamental Rayleigh wave and its third harmonic at about 39 and 104 MHz. A small area of a few square millimeters on the surface of the ZnO layer, in between the two IDTs, was illuminated by UV light at different light power values (from about 10 mW up to 1.2 W) through the back surface of the SiO2 substrate, which is optically transparent. The UV absorption caused a change of the ZnO electrical conductivity, which in turn affected the velocity and insertion loss (IL) of the two waves. It was experimentally observed that the phase velocity of the fundamental and third harmonic waves decreased with an increase in the UV power, while the IL vs. UV power behavior differed at large UV power values: the Rayleigh wave underwent a single peak in attenuation, while its third harmonic underwent a further peak. A two-dimensional finite element study was performed to simulate the waves IL and phase velocity vs. the ZnO electrical conductivity, under the assumption that the ZnO layer conductivity undergoes an in-depth inhomogeneous change according to an exponential decay law, with a penetration depth of 325 nm. The theoretical results predicted single- and double-peak IL behavior for the fundamental and harmonic wave due to volume conductivity changes, as opposed to the AE effect induced by surface conductivity changes for which a single-peak IL behavior is expected. The phenomena predicted by the theoretical models were confirmed by the experimental results.

Dual-Wave ZnO Film Ultrasonic Transducers for Temperature and Stress Measurements.

ZnO film ultrasonic transducers for temperature and stress measurements with dual-mode wave excitation (longitudinal and shear) were deposited using the reactive RF magnetron sputtering technique on Si and stainless steel substrates and construction steel bolts. It was found that the position in the substrate plane had a significant effect on the structure and ultrasonic performance of the transducers. The transducers deposited at the center of the deposition zone demonstrated a straight columnar structure with a c-axis parallel to the substrate normal and the generation of longitudinal waves. The transducers deposited at the edge of the deposition zone demonstrated inclined columnar structures and the generation of dominant shear or longitudinal shear waves. Transducers deposited on the bolts with dual-wave excitation were used to study the effects of high temperatures in the range from 25 to 525 °C and tensile stress in the range from 0 to 268 MPa on ultrasonic response. Dependencies between changes in the relative time of flight and temperature or axial stress were obtained. The dependencies can be described by second-order functions of temperature and stress. An analysis of the contributions of thermal expansion, strain, and the speed of sound to changes in the time of flight was performed. At high temperatures, a decrease in the signal amplitude was observed due to the decreasing resistivity of the transducer. The ZnO ultrasonic transducers can be used up to temperatures of ~500 °C.

High temperature AlN thin film ultrasonic transducers with dual mode wave excitation

AlN thin film ultrasonic transducers with dual mode wave (transverse and longitudinal) excitation were deposited by reactive RF magnetron sputtering technique. The transducers deposited at radial distances of 0 and 50 mm in the sample plane exhibited well-developed straight and inclined columnar structures with dominating (002) and (103) X-ray diffraction peaks, respectively. The transducers deposited at radial distances of 0, 30, and 50 mm demonstrated excitation of longitudinal, transverse, and longitudinal-transverse waves, respectively. Short term heat treatment was conducted in air within a temperature range of 20–900 °C to investigate the high temperature ultrasonic response. Temperature dependencies of the time-of-flight and pulse-echo amplitude were analyzed. Long term heat treatment in air at 700 °C for 192 h revealed a degradation of ultrasonic response due to the oxidation of the AlN layer.

Optical and photoelectrochemical properties of nitrogen-doped a-SiC thin films deposited by reactive sputtering method at room temperature

ABSTRACT This paper studies optical properties of Nitrogen-doped a-SiC amorphous, commonly called, silicon carbonitride (SiCN) thin films deposited on polished and textured silicon wafers by reactive RF magnetron sputtering technique. Different samples were made at room temperature by sputtering a silicon carbide (SiC) target in argon and nitrogen mixture environment. The FTIR measurement confirms the presence of Si-C and Si-N bonds. The peaks corresponding to Si-C are 611, 653, 669, 740, 834 cm−1 and the peaks corresponding to Si-N are in the range ~870–950 cm−1. The optical properties were achieved from reflectivity spectra by UV-visible spectroscopy. The refractive index (n < 2.5) and the optical gap (Eg>2.2 eV) of the deposited films depended on the used argon and nitrogen flows. The electrochemical properties of amorphous p-type a-SiC/N thin films on p-Si substrate were investigated as electrodes in H2SO4 aqueous solutions in the dark and under the white light illumination. The SiCN films show a good suitability for the antireflective coating application and can be applied to fabricate high efficient and stable SiCN catalysed n + p-Si photocathode with pyramid surface for PEC CO2 conversion.

Anticorrosive Behavior Enhancement of Stainless Steel 304 through Tantalum-Based Coatings: Role of Coating Morphology

Stainless steel (SS 304) has good mechanical strength and corrosion resistance properties, but it is not resistive to halides corrosion which limits the use of SS 304 in seawater applications. In this regard, the present work has been focused on the investigation of anticorrosive nature of Ta2O5 (tantalum pentoxide), Ta3N5 (tantalum nitride) and TaON (tantalum oxynitride) films deposited on AISI 304 stainless steel by RF reactive magnetron sputtering technique for anticorrosive applications. The predominant influencing factors especially film composition and surface morphology of the coatings were characterized by XRD, FE-SEM and AFM. The anticorrosive properties of the coatings were investigated through potentiodynamic polarization (Tafel) test and electrochemical impedance spectroscopy in 1M NaCl solution at room temperature. The morphological results showed that the films are uniform with low surface roughness, i.e., less than 10 nm. The contact angle and corrosion study of the films revealed that the tantalum oxynitride film, with nanoscale roughness, has greatly enhanced the corrosion protection of the stainless steel in 1M NaCl solution. The tantalum oxynitride film showed hydrophobic nature and the corrosion current density in the order of 10-11 A/cm2, which led to better anticorrosive behavior. The highest polarization resistance (Rp) was observed for tantalum oxynitride film, i.e., 3.14 MΩ. Overall, tantalum-based coatings have reduced the corrosion rate and enhanced the inhibition efficiency (more than 50%) in comparison with the bare SS 304 substrate.

Effect of substrate temperature on reactive RF magnetron sputtered SnO2 thin films for photovoltaic applications

SnO2 thin films were deposited using reactive RF magnetron sputtering technique at different substrate temperatures such as RT (S1), 200 °C (S2) and 400 °C (S3) in order to obtain highly crystalline as well as highly transparent films. The effect of substrate temperature on the structural, optical and electrical properties of SnO2 thin films was also studied. The observed XRD patterns indicated the formation of SnO2 in tetragonal phase with primitive lattice structure. UV–Vis-NIR spectroscopic analysis exhibited the high optical transparency (>90%) at the wavelength of 600 nm. Hall Effect measurements demonstrated the n-type conductivity of SnO2 thin films with high carrier concentration (-2.40 × 1020 to −8.40 × 1018 cm−3) and mobility (1.62 to 10.83 cm2/Vs) as well as low resistivity in the order of 10-2 Ω.cm for S1-S3. However, S2 (200 °C) is considered as potential candidate for photovoltaic applications because of reasonably high carrier concentration, enhanced crystalline nature, and also low processing temperature in addition to the suitable optical band gap (3.7 eV).

SiOC-Coated Silicon Nitride Platform for Efficient Phase Actuators

In this paper, integration of silicon oxycarbide (SiOC) and silicon nitride (Si3N4) platforms was demonstrated to realize ultra-efficient thermal tuning of photonic integrated circuits. Si3N4 being a fascinating photonic material with moderate refractive index (n ≈ 2) and ultra-low loss, lacks thermo-optic coefficient that makes thermal phase actuators long and dissipate high powers. Integration of SiOC coating with a comparable refractive index (n = 2.2) boosts the effective thermo-optic efficiency of Si3N4 photonic circuits by almost an order of magnitude with no additional loss. An SiOC layer was deposited by the reactive RF magnetron sputtering technique from the SiC target at room temperature. The structural, chemical and optical characterizations of the sputter deposited SiOC layer were performed with SEM, AFM, EDS and spectroscopic ellipsometry. The results of SiOC-coated Si3N4 and pristine Si3N4 photonic devices were discussed and compared. SiOC was demonstrated as an enabling platform for low-loss and power-efficient thermal phase actuators in conventional photonic technologies with application in reconfigurable photonic systems.

Silver oxides nanoparticle in gas sensors applications

In this work, silver oxide AgO films were prepared and deposited on glass substrates using RF reactive magnetron sputtering technique at different sputtering powers (100, 150 and 200) W. The X-Ray diffraction measurements showed that the prepared films are polycrystalline. It was found that the crystalline size and roughness of the surface, in addition the optical energy gap It has decreased with the increasing sputter power. One of the important results is the development of sensitivity with crystallization, where it was the best sensitivity at operating temperature 100 °C of the sample deposited at 200 W and at the concentration of target gas 600 ppm.

α-MoO3 nanostructure on carbon cloth substrate for dopamine detection

Orthorhombic molybdenum oxide (α-MoO3) nanostructures were deposited on the surface of carbon cloth (CC) as a flexible and high conductive scaffold by reactive RF magnetron sputtering technique. Structure and morphology of the as prepared molybdenum coated carbon cloth (MoO3CC) were thoroughly characterized with field emission scanning electron microscopy, x-ray diffraction, energy dispersive x-ray and Raman spectroscopy. Benefiting from high surface area and superior conductivity of CC as well as electrocatalytic activity of α-MoO3 nanostructures, an electrochemical sensor was fabricated. The electrochemical behavior of this new sensor toward determination of dopamine was studied in detail by cyclic voltammetry, amperometry (AM) and square wave voltammetry (SWV). Results reported here reveal that using SWV not only enhances the sensitivity of sensors to dopamine by more than 14 times compared to AM, but also offers higher linear dynamic range (1–700 μM compared to 5–550 μM). Limit of detection, for signal to noise ratio 3, was calculated to be 0.48 μM. Applicability of the proposed sensor for measurement of dopamine in real samples, like urine and pharmaceutical formulation, was also evaluated that concluded to satisfactory results.

Zirconium oxynitride films: Modulation of component as a function of the preparation parameters

Zirconium oxynitride films have recently received much attention because their properties may gradually be changed by varying the concentration of N, O and Zr constituents during processing. Here, we reported zirconium oxynitride films prepared by RF reactive magnetron sputtering technique. The films were deposited by different targets: ZrO2 and ZrN with the variation of nitrogen and oxygen flow rate. To explore whether the N content could be gradually incorporated into the films, two series of samples were prepared: one was prepared by the ZrO2 target with the variation of the nitrogen flow rate; the other was prepared by the ZrN target with the variation of the oxygen flow rate. The composition and structure of the films were investigated by XPS, EDS and XRD techniques. XPS results show that when the ZrO2 material was used as target the concentration of N was highly dependent on the flow rate of nitrogen, while the Zr concentration gradually decreased with the increase of N concentration; ZrO[Formula: see text]N[Formula: see text] and ZrO were formed. However, for ZrN used as target, the fresh film of the sample comprised of O and Zr elements without N detected. When the N2 was introduced as reactive gas with oxidized ZrN target, ZrO[Formula: see text]N[Formula: see text] film with a certain content of N was formed.

Anticorrosion Behavior of Deposited Magnetite on Galvanized Steel in Saline Water Using RF-Magnetron Sputtering

Thin films of Magnetite have been deposited on Galvanized Steel (G-S) alloy using RF-reactive magnetron sputtering technique and protection efficiency of the corrosion of G-S. A Three-Electrodes Cell was used in saline water (3.5 % NaCl) solution at different temperatures (298, 308, 318 &amp; 328K) using potentiostatic techniques with. Electrochemical Impedance Spectroscopy (EIS) and fitting impedance data via Frequency Response Analysis (FRA) were applied to G-S alloy with Fe3O4 and tested in 3.5 % NaCl solution at 298K.Results taken from Nyquist and Bode plots were analyzed using software provided with the instrument. The results obtained show that the rate of corrosion of G.S alloy increased with increasing the temperatures from 298 to 323K; and showed that deposition of Fe3O4 caused protection efficiency to reach 79.76% for G-S in 318K. In addition the enthalpy &amp; entropy of activation were evaluated. Apparent energies of activation have been calculated for the corrosion process of uncoated and coated G.S alloy by sputtering technique in saline water (3.5 % NaCl). The morphological analysis was carried out using Scanning Electron Microscopy (SEM) technique.

Microstructural and Mechanical Properties of Nanostructured Tungsten Nitride Thin Films Prepared by RF Reactive Magnetron Sputtering

In the present work, nanostructured tungsten nitride (WN) thin films were deposited by RF reactive magnetron sputtering technique in a mixture of N2 and Argon atmosphere and its microstructure and mechanical properties were investigated. The Argon pressure was kept constant at 20 sccm, while the N2 partial pressures were varied (3%, 5%, 10% and 15%). The WN thin films are deposited on SS304 stainless steel substrates at a temperature of 500 °C. The microstructural property was analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM) and mechanical properties were evaluated by nanoindentation technique. The XRD studies indicated the formation of different phases as a function of nitrogen content. The hardness and the young’s modulus values were in the range 27–39 GPa and 239–280 GPa, respectively. The high hardness values correspond to the coatings with the low nitrogen content and vice-versa. The mechanical properties of the tungsten nitride coatings were strongly influenced by the microstructure.

Anticorrosion Behavior of Deposited Magnetite on Galvanized Steel in Saline Water Using RF-Magnetron Sputtering

Thin films of Magnetite have been deposited on Galvanized Steel (G-S) alloy using RF-reactive magnetron sputtering technique and protection efficiency of the corrosion of G-S. A Three-Electrodes Cell was used in saline water (3.5 % NaCl) solution at different temperatures (298, 308, 318 &amp; 328K) using potentiostatic techniques with. Electrochemical Impedance Spectroscopy (EIS) and fitting impedance data via Frequency Response Analysis (FRA) were applied to G-S alloy with Fe3O4 and tested in 3.5 % NaCl solution at 298K.Results taken from Nyquist and Bode plots were analyzed using software provided with the instrument. The results obtained show that the rate of corrosion of G.S alloy increased with increasing the temperatures from 298 to 323K; and showed that deposition of Fe3O4 caused protection efficiency to reach 79.76% for G-S in 318K. In addition the enthalpy &amp; entropy of activation were evaluated. Apparent energies of activation have been calculated for the corrosion process of uncoated and coated G.S alloy by sputtering technique in saline water (3.5 % NaCl). The morphological analysis was carried out using Scanning Electron Microscopy (SEM) technique.

Influence of annealing time on the physical properties of reactively sputtered CuO thin film

Polycrystalline CuO thin film was deposited by reactive RF magnetron sputtering technique. The samples obtained from CuO film were annealed in air for different times. The structural, compositional and optical properties of unannealed and annealed samples were characterized. The SEM studies showed that the samples have a homogeneous surface morphology. All of the samples exhibited strong \((\bar{1}11)\) diffraction peak and optical transmittance above 70%. As the annealing time was increased, the grain size increased and the optical band gap decreased.

Investigation of structural and electrical properties of Zirconium dioxide thin films deposited by reactive RF sputtering technique

ABSTRACTZrO2 thin films with different thicknesses (400 nm, 500 nm, 600 nm) were deposited by reactive RF magnetron sputtering technique, on n-type Silicon (100) substrate at 200°C applying 125 W power ratin`g. The micro structural properties of thin films were obtained by Scanning Electron Microscope and it was observed that the films were grown successfully in the form of big grains formed by the accumulation of small particles. It was seen that the size of grains changed with the increase of film thickness. Energy-dispersive X-Ray spectroscopy was used to determine the chemical compositions of samples. The crystal structures of ZrO2 samples were analyzed by X-ray diffraction technique. In addition, the Current-Voltage and Capacitance-Voltage measurements were completed to investigate the electrical properties of samples.

Morphological evolution of zinc oxide thin films with variation in sputtering power and substrate temperature

Zinc oxide (ZnO) thin films were deposited on silicon substrates by reactive RF magnetron sputtering technique in order to investigate the evolution of the morphological and the optical properties as a function of different RF power and substrate temperature. Analysis of RF power and the substrate temperature have played a significant role in the morphological and the optical properties of the sputtered ZnO thin films. X-ray diffraction pattern of ZnO thin film has shown the appearance of c-axis-oriented (002) peak for all samples with variation in the degrees of crystallinity. The surface roughness as well as the average grain size of the ZnO films found to be decreased with RF power, where as the films grown at higher temperature has shown the evolution of larger grains. ZnO films, deposited at 150 W RF power and substrate of 200°C, have shown better optical properties.

Morphological evolution of zinc oxide thin films with variation in sputtering power and substrate temperature

Zinc oxide (ZnO) thin films were deposited on silicon substrates by reactive RF magnetron sputtering technique in order to investigate the evolution of the morphological and the optical properties as a function of different RF power and substrate temperature. Analysis of RF power and the substrate temperature have played a significant role in the morphological and the optical properties of the sputtered ZnO thin films. X-ray diffraction pattern of ZnO thin film has shown the appearance of c-axis-oriented (002) peak for all samples with variation in the degrees of crystallinity. The surface roughness as well as the average grain size of the ZnO films found to be decreased with RF power, where as the films grown at higher temperature has shown the evolution of larger grains. ZnO films, deposited at 150 W RF power and substrate of 200°C, have shown better optical properties.

Finite Element Modeling and Synthesis of c-axis Tilted AlN TFBAR for Liquid Sensing Applications

Thin film bulk acoustic resonator (TFBAR) with c-axis tilted AlN finite element modeling was performed using COMSOL Multiphysics simulation software. Depending on the AlN c-axis tilt angle, dual mode TFBAR can be obtained that operate in longitudinal and shear mode: the former mode is a thickness-extensional mode, while the latter is a thickness-in plane-shear mode that is suitable for liquid sensing applications. The acoustic wave displacement, the resonator frequency and equivalent admittance of the TFBARs with different tilt angles and electrode thicknesses were simulated to obtain the optimum design (high electroacoustic coupling efficiency and large quality factor Q) for shear mode operation. Furthermore, AlN films having the c-axis tilted up to about 30̊ from the substrate normal were successfully grown on silicon (100) substrates by reactive rf magnetron sputtering technique at 200̊C.

Study of Structural Properties of N-Doped ZnO Thin Film Prepared by Reactive Gas-Timing RF Magnetron Sputtering

We examined structural properties of nitrogen doped (ZnO:N) thin films prepared by reactive RF magnetron sputtering technique in conjunction with gas timing method. The deposited films were polycrystalline ZnO in wurtzite structure. Morphology of the ZnO:N films could be modified by adjusting gas timing conditions. The x-ray photoelectron spectroscopy (XPS) and extended x-ray absorption fine structure (EXAFS) analysis showed that incorporation of nitrogen may cause structural distortion in the ZnO:N crystal.