RF Magnetron Sputtering Technique Research Articles

Up to 98.2% super transmittance and precise modification of wavelength band in vein-like Ag in ITO/Ag/AZO sandwich structure

High transmittance and low resistance ITO/Ag/AZO (IAA) sandwich structures were fabricated as transparent electrodes through a combination of the pulsed laser deposition (PLD) and the RF magnetron sputtering techniques. The Ag in the middle layer forms vein-like network in the IAA structure, resulting in improved electrical conduction. The maximum transmission in different wavelength bands of the IAA structure was achieved by changing the thickness of each layer. The highest transmittance of 98.24% was observed at 486 nm for the structure with Ag-layer thickness of 8 nm. By optimizing the layer thicknesses of the fabricated structure, the lowest sheet resistance of 5.8 Ω/□ with an average transmittance of 90.28% in the visible region was obtained for the ITO (35 nm)/Ag (10 nm)/AZO (35 nm) electrode. The transmittance wavelength band of the IAA structure was modified precisely by controlling the layer thickness of the ITO and AZO films. The highest figure of merit (FOM) value of 1.21 × 10−1 Ω−1 was obtained for the ITO (35 nm)/Ag (10 nm)/AZO (35 nm) electrode, which suggests a high potential of these electrodes for application in the photovoltaic devices.

Fabrication and Characterization of Aluminum Nitride Nanoparticles by RF Magnetron Sputtering and Inert Gas Condensation Technique

Aluminum nitride nanoparticles (AlN-NPs) were fabricated by a RF magnetron sputtering and inert gas condensation technique. By keeping the source parameters and sputtering time of 4 h fixed, it was possible to produce AlN-NPs with a size in the range of 2–3 nm. Atomic force microscopy (AFM), Raman spectroscopy, X-ray diffraction (XRD), and UV-visible absorption were used to characterize the obtained AlN-NPs. AFM topography images showed quazi-sphere nanoparticles with a size ranging from 2 to 3 nm. The XRD measurements confirmed the hexagonal wurtzite structure of AlN nanoparticles. Furthermore, the optical band gap was determined by the UV-visible absorption spectroscopy. The Raman spectroscopy results showed vibration transverse-optical modes A1(TO), E1(TO), as well as longitudinal-optical modes E1(LO), A1(LO).

Enhanced perpendicular magnetic anisotropy of sputtered Pr-Fe-B thin film by inter-layer diffusion Fe–Si layer

The Pr-Fe-B thin films with c-axis texture deposited on glass substrate with Si3N4 underlayer were prepared by RF magnetron sputtering technique in high vacuum chamber and in-situ heat treatment. The effects of the magnetic layer thickness as well as in-situ heat treatment on the microstructure and magnetic properties of the Pr-Fe-B films with perpendicular magnetic anisotropy (PMA) were investigated. The PMA and coercivity were studied as the function of thickness varying from 50 to 500 nm, and at the annealing temperatures ranging from 500 to 700 °C. The results showed that the PMA and coercivity were better at the magnetic layer thickness of 125 nm and in the annealing temperature of 650 °C. With this compatible thickness and in-situ heat treatment, the formation of Fe3Si layer by effective inter-diffusion of the main magnetic layer and underlayer supported significantly the Pr2Fe14B phase as well as the PMA strength. The higher coercivity was achieved at 7.5 kOe. The surface morphology was more blossom like. XPS analysis exhibited the distribution of the main magnetic elements that strongly affected by the heat energy at the same thickness through the elemental depth profile.

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.

Application of Ni-doped ZnO deposited by RF magnetron sputtering technique on FTO as a photoanod in Photo-Electrocatalysis process of Ofloxacin degradation: synthesis, kinetics, and ecotoxicity study

ABSTRACT In this work, a novel Ni-doped ZnO nano-electrocatalyst was synthesised via depositing on fluorine-doped tin oxide glass (FTO) and utilised for the successful degradation of Ofloxacin (OFL). Firstly, the Ni and ZnO foils were sputtered using Radio-Frequency Sputtering power 100 watts and time 60 min. Furthermore, the effect of operating variables (i.e., initial pH, electrical current, initial concentration of OFL, and reaction time), was investigated on the degradation of OFL by the Photo-electrocatalytic process through UV-A irradiation. Results demonstrated the suitable degradation of OFL, about 100% in optimal conditions. The reaction came after the first-order kinetics model, with an average R2 of 0.96. Based on the results, single processes (photolysis and electrolysis) and photocatalytic processes have much lower efficiency for OFL removal in comparison with the Photo-electrocatalytic process. This decrease in the toxicity unit is evident in different reaction times. Based on the GC-MS analysis, eight possible degradation pathways intermediate of OFL can be proposed. Also, the stability test of the electrode indicated that after nine continually runs, only 1.4% efficiency of the process decreased.

Nonlinear optical absorption switching behavior of BaTiO3 in asymmetric microcavity

In this paper, an asymmetric 1-D photonic microcavity with BaTiO3 as defect has been fabricated using RF magnetron sputtering technique. Open aperture Z-scan shows enhancement in nonlinear absorption of BaTiO3 due to strong field confinement around the defect layer. We further report the switching behavior in nonlinear absorption from reverse saturable absorption to saturable absorption in response to the angle tuning of the sample. The transfer matrix simulation results further support the cavity defect in asymmetric photonic crystal confine the photon and thereby enhancing nonlinear optical phenomena.

Sputtering pressure influenced structural, electrical and optical properties of RF magnetron sputtered MoO3 films

Abstract MoO3 films were deposited by RF magnetron sputtering technique on glass and silicon substrates held at 473 K by sputtering of metallic molybdenum target at an oxygen partial pressure of 4 × 10−2 Pa and at different sputtering pressures in the range of 2 Pa to 6 Pa. The influence of sputtering pressure on the structure and surface morphology, electrical and optical properties of the MoO3 thin films was studied. X-ray diffraction studies suggest that the films deposited at a sputtering pressure of 2 Pa were polycrystalline in nature with mixed phase of α- and β-phase MoO3, while those formed at sputtering pressure of 4 Pa and above were of α-phase MoO3. Scanning electron micrographs showed a decrement in the size of the particles and their shapes changed from needle like structure to dense films with the increase of sputtering pressure. Fourier transform infrared spectroscopic studies confirmed the presence of characteristic vibration modes of Mo=O, Mo–O and Mo–O–Mo related to MoO3. Electrical resistivity of the MoO3 films decreased from 6.0 × 104 Ω cm to 2 × 104 Ω cm with an increase of sputtering pressure from 2 Pa to 6 Pa, respectively. Optical band gap of the films decreased from 3.12 eV to 2.86 eV with the increase of sputtering pressure from 2 Pa to 6 Pa, respectively.

Characterization and device application of indium doped ZnO homojunction prepared by RF magnetron sputtering

Undoped and Indium doped Zinc Oxide (IZO) nanocrystalline thin films were synthesized via RF magnetron sputtering techniques using home-made cold pressed powder targets. The morphology, crystal structure, elemental analyses were studied using FESEM, AFM, XRD, EDS and XPS techniques. All the films showed hexagonal wurtzite structure, and revealed appreciable variations in (100), (002) and (101) peak intensities with indium doping. The incorporation of In into the ZnO films was confirmed by both EDS and XPS measurements. XPS and Photoluminescence (PL) studies of doped films demonstrated significant reduction of oxygen vacancies (Vo) after incorporation of indium in ZnO lattice at substitutional sites. PL spectra showed convoluted peaks, which correspond to band to band transitions and defect level emissions. The optical studies showed high transmittance of over 90% in the UV–vis region and exhibited the absorption edge near 380 nm. The band gap energy of the films increased from 3.27 eV to 3.42 eV, with In content. In addition, typical rectifying I–V characteristics of SZO/IZO homojunction layers were demonstrated.

Investigation of the Influences of Post-Thermal Annealing on Physical Properties of TiO2 Thin Films Deposited by RF Sputtering

For this study, titanium dioxide (TiO2) thin films were deposited on glass substrates at room temperature by the RF magnetron sputtering technique. The preparation parameters that offer better control and reproducibility of film fabrication were first optimized. Then, the effects of post-deposition annealing temperature at 350, 450, and 550°C on the microstructure, surface morphology, and optical properties of the prepared films were investigated using X-ray diffraction (XRD), Raman spectroscopy (RS), scanning electron microscopy (SEM), atomic force microscopy (AFM), and UV–Visible (UV–Vis) spectrophotometry. Interestingly, XRD analysis shows that as-deposited and annealed TiO2 film possess anatase crystal structure only with a preferential orientation along the (101) plane. The intensity of the (101) diffraction peak and crystallite size are found to increase with increasing annealing temperature, which indicates an improvement in the crystallinity of the films. Raman spectra confirm that all samples possess anatase phase and the crystallinity is enhanced with increasing thermal annealing. From the analysis of SEM and AFM images, it is revealed that the heat treatment significantly affects the morphology, grain size, and surface roughness of the TiO2 films. The UV–Vis spectroscopy analysis shows that as-deposited TiO2 thin film is highly transparent in the visible region with an average transmittance about 84%, whereas the transmission decreases slightly with an increase in annealing temperature. Moreover, the optical band gap energy shows a red shift with increasing the annealing temperature.

Highly sensitive, ultra-low dark current, self-powered solar-blind ultraviolet photodetector based on ZnO thin-film with an engineered rear metallic layer

In this paper, novel self-powered, solar-blind UV photodetector (PD) designs based on a ZnO thin-film with engineered back metal layer (BML) were fabricated by RF magnetron sputtering and e-beam evaporation techniques. An exhaustive study concerning the impact of dissimilar BML (Au and Ni) on the device structural, optical and electrical properties was carried out. The measured I–V curves illustrated an asymmetrical behavior, enabling a clear and distinctive photovoltaic mode. Superb sensitivity of 107, high ION/IOFF ratio of 149dB, ultralow dark-noise current less than 11pA and responsivity exceeding 0.27A/W were reached for the prepared ZnO-based UV-PDs in self-powered mode. The role of the engineered BML in promoting effective separation and transfer of the photo-induced carriers was discussed using the band-diagram theory. The influence of the annealing process on the UV-sensor performance was also investigated. The annealed device at 500°C demonstrated a lower dark current of a few picoamperes and a high rejection ratio of 2.2×103, emphasizing its exciting visible blindness characteristics. Therefore, the use of an engineered BML with optimized annealing conditions open up new perspectives to realizing high-performance, self-powered solar-blind UV-PDs based on simple thin-film-ZnO structure strongly desirable for various optoelectronic applications.

Cr doping effect on the structural, optoelectrical and photocatalytic properties of RF sputtered TiO2 thin films from a powder target

In this study, thin films of pure and chromium doped TiO2 were deposited by RF magnetron sputtering technique with recourse to a low cost powder target. The dopant concentration was varied from 0 to 6 wt%. The structural, optical, electrical and photocatalytic properties of the sputtered deposited films were systematically investigated on the basis of the incorporated Cr content. XRD analysis revealed that the elaborated films are polycrystalline and have a preferential orientation along the (110) plane, characteristic of the rutile phase. The optical measurements showed a good homogeneity of the films and a high transmission that reached 85% in the visible range. The high transparency of these films allows their use as an optical window in thin film solar cells. Optical band gap decreased from 3.44 eV to 3.32 eV with the increase of the Cr content. In addition, the impedance spectroscopy analysis showed that the conductivity increases along with increasing frequency and temperature, and that the conduction mechanism follows the correlated barrier hopping model. The test of the catalytic efficiency of the chromium-doped TiO2 thin films at different concentrations demonstrated a degradation of the methylene blue (MB) and an improvement of the photocatalytic activity and that the 6 wt% doped thin films have the best photocatalytic activity.

Boron Carbon Nitride (BCN) Nano-Coatings of Central Venous Catheters Inhibits Bacterial Colonization

Central line associated bloodstream infections (CLABSI) are commonly induced due to bacterial colonization of medical devices such as central venous catheters (CVCs) and is leading cause of concern due to increasing hospitalization duration, costs, and morbidity. This study evaluated the efficacy of boron carbon nitride (BCN) nano-coatings on CVC for antimicrobial activity. RF magnetron sputtering technique was utilized to deposit nano-coatings of BCN on CVCs. For comparison purposes, RF magnetron sputtered TiO2 nano-coatings were also investigated. Antimicrobial activity of nano-coatings was tested against gram-positive Bacillus cereus and gram-negative Escherichia coli bacterial cells. Nanoparticle coated and uncoated catheter surfaces were studied using FE-SEM and AFM to determine if the surface characteristics correlated with anti-adhesive effects of the bacteria. Biofilm formation on uncoated and BCN coated catheters was quantified using absorbance spectrophotometry.

Characterization of Zinc Sulphide thin films prepared using RF-sputtering technique

Nanocrystalline Zinc Sulphide (ZnS) thin films were synthesized via RF magnetron sputtering technique on glass substrates. The influence of deposition parameters and post- deposition thermal annealing on the structural, morphological and optical properties was studied in detail. X-ray diffraction studies revealed the nanocrystalline nature of the films along with their crystalline perfection, indicated by the preferential orientation of the grains. Thin films were prepared with RF power ranging 100 W–250 W. The depositions were also performed for three different sputtering durations (10, 20, 30 min) with fixed RF power and also studied the effects of thermal annealing on the structural and optical properties of ZnS thin films. The films were characterized by x-ray diffraction (XRD), Scanning Electron Microscope and UV–Visible Spectroscopy.

Insight of the doping mechanism of F and Al co-doped ZnO transparent conductive films

Transparent conductive oxide (TCO) films, as transparent electrodes, are widely used in thin-film solar cells. The performance of TCO film has a significant influence on the conversion efficiency of the film solar cell fabricated byusing it. Although the conductivity can be improved by increasing the carrier concentration, the transmittance in the long wave will be sacrificed. Therefore, the only feasible method is to increase the carrier mobility within a certain carrier concentration range, rather than increase the mobility by reducing carrier concentration. In this paper, the F and Al co-doped ZnO (FAZO) films are deposited on glass substrates (Corning XG) by an RF magnetron sputtering technique with using a small amount of ZnF<sub>2</sub> (1 wt.%) and Al<sub>2</sub>O<sub>3</sub> (1 wt.%) dopant. The influences of sputtering pressure on the structure, morphology and photoelectric characteristics of the films are respectively investigated by X-ray diffraction analysis, scanning electron microscope, Hall effect measurement, and ultraviolet–visible–near infrared spectrophotometry. All the thin films show typical wurtzite structure with the <i>c</i> axis preferentially oriented perpendicular to the substrate. With the increase of sputtering pressure, the deposition rate of FAZO film decreases, the crystallization quality is deteriorated, surface topography changes gradually from “crater-like” to co-existent “crater-like” and “granular-like”, and the surface roughness increases. The FAZO film deposited at 0.5 Pa presents the optimal performance with a mobility of 40.03 cm<sup>2</sup>/V·s, carrier concentration of 3.92 × 10<sup>20</sup> cm<sup>–3</sup>, resistivity of 3.98 × 10<sup>–4</sup> Ω·cm, and about 90% average transmittance in a range of 380－1200 nm. The theoretical result shows that the co-doping of F and Al takes the advantages of single F and Al doped ZnO films, and overcomes the shortcoming of metal elements doping, which donates the carriers just from doped metal elements. Furthermore, the co-doping of F and Al not only increases the carriers but also reduces the scatterings caused by the inter-orbital interaction of doped atoms. The doped F 2p electron orbitals repel the O 2p and Zn 4s electron orbitals, making them move down and donate electrons. At the same time, the orbitals of Al 3s and Al 3p also make a contribution to the conductivity. After co-doping of F and Al, both the carrier concentration and conductivity increase significantly.

First Proof-of-Principle of Inorganic Lead Halide Perovskites Deposition by Magnetron-Sputtering.

The present work reports the application of RF-magnetron sputtering technique to realize CsPbBr 70 nm thick films on glass substrate by means of a one-step procedure. The obtained films show highly uniform surface morphology and homogeneous thickness as evidenced by AFM and SEM investigations. XRD measurements demonstrate the presence of two phases: a dominant orthorhombic CsPbBr and a subordinate CsPbBr. Finally, XPS data reveals surface bromine depletion respect to the stoichiometrical CsPbBr composition, nevertheless photoluminescence spectroscopy results confirm the formation of a highly luminescent film. These preliminary results demonstrate that our approach could be of great relevance for easy fabrication of large area perovskite thin films. Future developments, based on this approach, may include the realization of multijunction solar cells and multicolor light emitting devices.

An efficient ITO-free transparent electrode based on diamond-like carbon with an engineered intermediate metallic thin-film

In this paper, a novel Diamond-Like Carbon (DLC)-based structure is proposed as an alternative material for transparent electrode applications. In this context, DLC/Ag/DLC multilayer structure was successfully fabricated by combining pulsed laser deposition (PLD) and RF magnetron sputtering techniques. DLC films were deposited at room temperature via PLD on a quartz substrate and their optical constants were extracted using ellipsometry technique. A new hybrid approach based on FDTD method supported by particle swarm optimization (PSO) technique was introduced to find out the best geometry and appropriate intermediate ultrathin metal film of the DLC/Metal/DLC multilayer structure, promoting wider opportunities to overcome the transparency-conductivity trade-off. The optimized design is then prepared by successively depositing DLC films and sputtering ultra-thin Ag layer. Characterizations showcased that the elaborated DLC/Ag/DLC tri-layered structure offers a high Haacke FoM of 55.2 × 10−3 Ω−1, emphasizing the ability of the presented systematic investigation for providing promising pathways to reach enhanced light management and reduced resistive losses. Therefore, the elaborated DLC/Ag/DLC multilayer structure opens up new perspectives towards realizing high-performance transparent electrodes based on free-critical raw materials (CRM), which are strongly desirable for optoelectronics and low cost thin film photovoltaic applications.

Influence of deposition temperature on the structural and dispersion parameters of TiO2 thin films

Polycrystalline TiO2 thin films were deposited onto quartz substrates using RF magnetron sputtering technique at different substrate temperatures (573 K, 623 K, 673 K, and 773 K). X-ray diffraction (XRD) measurements revealed the isolation of anatase phase with (101) preferred crystal orientation for the film deposited at 773 K. Moreover, the topographical features of this film clarified the smoothness of the deposited films, with root mean square roughness (RMS) of 0.5 nm. The optical properties of the as-prepared thin films at different deposition temperatures was enlightened through structural correlation. Most of the films were transparent with transmittance intensity extending from 50 to 90% within the visible range. Due to the smoothness of the deposited films, the transmittance and reflectance spectra exhibited an oscillatory behavior. Additionally, from single effective oscillator model, the dispersion parameters were estimated. For the deposited films, the single oscillator energy (Eo), dispersion energy (Ed), lattice dielectric constant (eL), and infinite permittivity (e∞) extended in the range (3.42 ~ 3.99), (9.83 ~ 24.12), (4.39 ~ 7.75), and (3.88 ~ 7.04), respectively.

Effect of rapid thermal annealing on structural and optical properties of ZnS thin films fabricated by RF magnetron sputtering technique

The ZnS thin films have been deposited by radio frequency magnetron sputtering at room temperature. Post-deposition rapid thermal annealing treatment was done for the films deposited at different powers ranging from 70 to 100 W. One peak is observed for as-deposited and annealed thin films at around 28.48° corresponding to the (111) reflection plane indicating a zincblende structure. The overall intensity of the peaks and the FWHM values of as-deposited films increased after annealing corresponding to the increase in crystallinity. The optical energy bandgap is found in the range of 3.24–3.32 eV. With increasing annealing temperature, the decrease in the Urbach energy values indicating a decrease in localized states which is in good agreement with the XRD results where the crystallinity increased. The surface morphology of the films seems to be composed of Nano-granules with a compact arrangement. Apparently, the grain size increases in the deposited films as annealing temperature increases. The compositional ratio attained close to the stoichiometric ratio of 1:1 after annealing. From the Hall effect measurement, the carrier concentration and mobility are found to increase after annealing. The high carrier concentration and mobility also comply with structural and optical analysis. Best results are found for the film annealed at 400 °C deposited at 90 W.

The phase optimization, optical and electrical properties of kesterite Cu2ZnSnS4 thin film prepared by single target RF magnetron sputtering technique for solar cell application

Cu2ZnSnS4 (CZTS) thin film was prepared by RF sputtering technique from a single quaternary target by optimizing RF power, in situ substrate temperature and post deposition annealing temperature. The single phase formation of crystalline CZTS thin film has been verified at a particular optimized condition by characterizing through x-ray diffraction, Raman spectrometer and x-ray photoelectron spectroscopy. The kesterite structure has been further confirmed from the lattice fringes of high resolution transmission electron microscope and selected area electron diffraction study. The surface properties such as particle size, shape and roughness and elemental composition of amorphous and crystalline phase of CZTS studied by atomic force microscope, scanning electron microscope and energy dispersive analysis of x-rays. The optical absorption and photoluminescence studies of post-deposition annealed film prove the defect free and single phase CZTS formation. The band gap calculation for crystalline CZTS showed band gap of 1.49 eV calculated from the Tauc plot. The electrical properties of optimized CZTS thin film has been studied from Hall effect measurement showing P-type conductivity with better carrier concentration and Hall mobility.

Irradiation enhanced electric property of Palladium doped diamond like carbon thin films

The effect of copper (Cu2+) ions (300 keV) irradiation on the morphological, structural and electrical properties of palladium (Pd) doped diamond like carbon (Pd-DLC) thin films have been studied. The DLC and 5% Pd-DLC thin films are prepared by using RF magnetron sputtering technique. 5% Pd-DLC films are irradiated with Cu2+ (300 keV) ions having 2 × 104 and 4 × 104 atoms/cm2/s fluence rate. SEM, Raman and four point probes are used to analyze morphological, structural and electrical properties of these thin films, respectively. Raman spectroscopy results confirmed about the reduction in internal stress and increase in graphitization nature of films due to Pd and Cu ions incorporation. The maximum graphitization character is obtained at 4 × 104 ions cm−2 s−1 fluence rate. SEM results showed that Pd-Cu metal’s cluster formation on the surface of doped and irradiated films. This conducting metal’s cluster formation is responsible for the enhancement in electrical properties of Pd-DLC thin films. Four point probes results showed the highly improved electrical properties at fluence rate of 4 × 104 atoms/cm2/s. These results can be applied in various electronics industries due to high conductivity.