Physical Vapor Deposition Method Research Articles

Electroplating-based engineering of plasmonic nanorod metamaterials for biosensing applications

Sensing lower molecular weight in a diluted solution using a label-free biosensor is challenging and requires a miniaturized plasmonic structure, e.g. a vertical Au nanorod (AuNR) array-based metamaterials. The sensitivity of a sensor mainly depends on transducer properties and hence for instance, the AuNR array geometry requires optimization. Physical vapour deposition methods (e.g. sputtering and e-beam evaporation) require a vacuum environment to deposit Au, which is costly, time-consuming, and thickness-limited. On the other hand, chemical deposition, i.e. electroplating deposit higher thickness in less time and at lower cost, becomes an alternative method for Au deposition. In this work, we present a detailed optimization for the electroplating-based fabrication of these metamaterials. We find that slightly acidic (6.0 < pH < 7.0) gold sulfite solution supports immersion deposition, which should be minimized to avoid uncontrolled Au deposition. Immersion deposition leads to plate-like (for smaller radius AuNR) or capped-like, i.e. mushroom (for higher radius AuNR) structure formation. The electroplating time and DC supply are the tuning parameters that decide the geometry of the vertically aligned AuNR array in area-dependent electroplating deposition. This work will have implications for developing plasmonic metamaterial-based sensors.

EBM Technique Study on Microstructural Characterization of Al-Zr-N Coating

Through the implementation of the electron beam physical vapour deposition (EB-PVD) technique, an aluminium zirconium nitrate (Al-Zr-N) coating has been created in the current work on high speed steel (E19) substrates. Through the use of X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), nano indentation, and scratch tests, the structural morphological and mechanical properties of the substrate are investigated. The cause of tension relaxation and vacancy concentration is explained by the fluorite phase's lattice constant decreasing with rising deposition temperature. As the temperature of the substrate rises, the coating's increased surface roughness is explained by an increase in crystallite size [1]. TBCs are frequently applied to metal substrates using the Atmospheric Plasma Spraying (APS) and Electron Beam Physical Vapour Deposition (EB-PVD) methods. For the next generation of turbine engines, the high costs and relatively high thermal conductivities of EB-PVD coatings, as well as the short thermal lifetime of APS coatings, are significant drawbacks. Suspension Plasma Spraying (SPS) was evaluated in this study to enhance the thermal properties of TBC. The SPS process enables the creation of columnar micro-structures that are easily adjustable in terms of thermal conductivity and columnar structure compaction.

Bipolar Switching Properties of GdOx:SiO2 Thin Film Resistive Random Access Memory Using Co-Sputtering Technology

Using two kinds of targets (gallium and silicon dioxide) and the rf magnetron sputtering deposited technique, GdOx:SiO2 thin film RRAM devices were deposited on TiN/Si substrate to form a metal–insulator–metal (MIM) structure. In addition, different oxygen concentrations and rf sputtering power parameters were prepared for the GdOx:SiO2 thin films. Decrease of the defects and oxygen vacancies of the GdOx:SiO2 thin films were used and repaired by rapid thermal annealing technology. Indium tin oxide (ITO) as the top electrode on the GdOx:SiO2 thin film was prepared by the physical vapor deposition (PVD) method, and ITO/GdOx:SiO2/TiN/Si structures of the GdOx:SiO2 thin films’ RRAM devices were also made. In addition, the current–voltage curves and devices’ endurance properties were measured by an impedance analyzer. Finally, the crystalline style, the preferred phase, the grain size, and surface microstructure of the thin films were analyzed and observed from X-ray diffraction and field emission scanning electron microscope measurements.

Thermal Oxidation of Tungsten Coatings for Detection by Infrared Spectrometry Method

Physical vapor deposition (PVD) of metallic thin films is used extensively in the fabrication of semiconductor technology devices - use as of lately for them have grown. Tungsten (W) is a low resistivity, refractory metal, that is often deposited by PVD methods for use as a gate contact to semiconductor devices and due to the low work function and high thermal stability, W can be used for the fabrication of field emitters in microelectronics [1-3]. In order to monitor quality of the synthesized thin films by magnetron sputtering method, it is necessary to develop methodology suitable for the analysis of these thin films. Infrared spectrometry is a sensitive method for the analysis of chemical bonds, but W thin films contain weakly polar and non-polar W-W bonds, that cannot be directly detected by infrared spectrometry, therefore oxidation of W is selected as thermal oxidation method for detecting oxidized products for thin films of thickness 150 nm, for instance, W-O bonds. After oxidation, it was observed, that the oxidation of W thin films takes place already at a 600 °C in the air atmosphere. The Fourier transform infrared spectrometry (FTIR) spectra of modified coatings showed formation of additional new signals in the region of 700-900 cm−1 attributed to W-O, O-W-O, W=O bonds - formation of W-oxygen bonds on Si-SiO2 substrate was achieved. For coating homogeneity and production quality formation, additionally synthesized control samples are recommended for FTIR analysis.

SYNTHESIS AND INVESTIGATION OF STRUCTURAL, SURFACE MORPHOLOGICAL AND OPTICAL PROPERTIES OF InSe/PMItz HYBRID HETEROJUNCTION

On a series of annealed and unannealed InSe thin films which were formerly produced by electrochemical deposition method, organic PMItz semiconductor compound was growth by physical vapour deposition (PVD) method. Structural analyses of the films carried out by X-ray diffractometry (XRD) method revealed that glass/ITO/InSe film formed in hexagonal InSe phase while glass/ITO/InSe(annealed) film formed in monoclinic In6Se7 and orthorombic In4Se3 phases. Surface analyses of the layers forming heterojunction were conducted by atomic force microscoby (AFM) and it is observed that the layers are homogenous and have different roughness values. Optical analyses of the films demonstrated that annealing of the film result with increased absorption coefficient and reduced energy band gap. Moreover, other optical parameters of the films i.e. refractive indice(n), extinction coefficient (k), real dielectric constant(Er), imaginary dielectric constant(Ei) and optical conductivity were determined and compared within 300-1000 nm range.

INVESTIGATION OF THE EFFECT OF NANOCOATINGS ON THE WEAR-RESISTANCE OF SOCKET CARBIDE MILLS

The results of studies of the wear-resistance of socket mills made of hard alloys in the processing of hard-to-process structural chromium steels are presented. The technology of hardening of cutting teeth with a wear-resistant coating obtained by the Physical Vapour Deposition method is considered. The influenceof the structure of the hardening composite coating based on titanium nitrides and carbonitrides on the mechanical characteristics and working capacity of the tool is shown. The nature of wear and brittle destruction of the working surfaces of the tool under intermittent cutting conditions and the influence of wear-resistant coatings on the thermal and stress state of the cutting wedge in the contact zone are investigated.

Indirect Production of Chromium Carbides Film on Low Alloy Steel

Chromium carbide coatings deposited on mechanical parts by different techniques have an interesting hardness, wear-resistant and corrosion resistance. Some studies show that chromium carbides produced by physical vapor deposition methods and revealed a superior hardness present a poor adherence to their substrates. The objective of this study is to indirectly obtain a hard, and adherent coating of chromium carbide by using a conversion treatment including carburizing treatment of steel substrate, deposition of a pure chromium layer, and annealing treatment of coated carburized steel under a carbonic gas atmosphere. Treatment temperature has an effect on the partial or complete conversion of chromium film as a result of the diffusion and precipitation process. The transformation rate of chromium into both chromium carbide layers was investigated. For 1 h of holding treatment, chromium film was totally transformed at 900 °C into chromium carbide film which presented high hardness and excellent adhesion.

Room-Temperature Excitonic Nanolaser Array with Directly Grown Monolayer WS2

Two-dimensional (2D) transition-metal chalcogenides (TMDCs) with strong excitonic emission are ideal candidates for small-volume gain materials in nanolasers, which can be realized by integrating 2D TMDCs with optical microcavities. However, at present, the integration is usually realized by the transfer method, which is not suitable for large-scale production, and the quality factor of the microcavity usually drops sharply in the process of transfer. Therefore, scalable fabrication of nanolasers remains an urgent issue to be solved. In this paper, by embedding continuous monolayer WS2 between silicon nitride (Si3N4) microdisks and Al2O3, we demonstrated the room-temperature transfer-free excitonic nanolaser array. Lasing at room temperature is achieved with the help of the high-quality-factor Si3N4 microdisks and the physical vapor deposition method for growing 2D gain material directly. This work provides a practical solution for large-scale and low-cost TMDC-based nanolaser arrays in the integrated optical communication systems.

Effect of the metallization method on properties of hybrid zirconia/Ti–6Al–4V joints

The addition of titanium powder and physical vapor deposition of titanium were applied for metallization of zirconia surface. The hybrid members of stabilized ZrO2/Ti–6Al–4V were fabricated using the Ag–28Cu filler metal. Different phases including TiCu3, Ti3Cu3O, Ti2Cu, and Ti6O were observed in the microstructure of joints. The sound joints were obtained when physical vapor deposition method was used for metallization; while various defects were observed after addition of the metallic powder to the joint. The increased thickness of filler metal or the metallized layer of zirconia promoted formation of the interaction layer between ceramic and filler metal. The formation of Ti3Cu3O along the joint interface encouraged the brittle fracture and decreased strength of the dissimilar joint. The maximum shear strength of the joint was obtained for the specimen which was metallized for 6 min by the physical vapor deposition method and was joined using the 50 μm thick filler metal.

Morphology and optical properties of CdS thin films prepared by Physical Vapor Deposition method

The optical properties of cadmium sulfide thin films obtained by thermal evaporation in vacuum were studied. The stoichiometric compositions of the binary compound previously synthesized from high-purity powders of the initial components were used. Films of different thicknesses deposited on a glass substrate were investigated using scanning electron microscopy and absorption coefficient was defined by the Swanepoel method. It was found that with increasing film thickness, surface formations decrease and at a thickness of 1 μm the film surface is continuous. It is determined that thin films of cadmium sulfide have optimal optical parameters for use as photovoltaic buffer layer. All the obtained films except the film with a thickness of 1215 nm show the usual interference pattern in the reflection spectra.

Controlled Growth and Chemical Engineering of FeSe‐Based Superconducting Films

AbstractChemical engineering tailors functional materials to meet the demands of physical and chemical properties, accelerating materials discovery and design in a multidisciplinary field. However, stereotyped synthetic paradigms in physical and chemical approaches obstruct the effective integration of multiple advantages of respective materials exploration methods. Solid state reaction is often considered separately with wet chemistry synthesis route, such as film growth using physical vapor deposition and hydrothermal methods. Here, the controlled growth of FeSe thin films by physical deposition techniques followed by the chemical engineering to create heterogenous interface in FeSe films via a solution‐based environment is demonstrated. The two‐step route allows an expanded crystal structure and enhanced superconducting transition temperature from 3.6 to 38 K, providing a new strategy to design functional hybrid materials.

Tunable polarized terahertz wave generation induced by spontaneous polarization-dependent ultrafast shift current from vertically grown ferroelectric SnS

Ferroelectric group-IV monochalcogenides $MX$ ($M=\mathrm{Sn}/\mathrm{Ge}$ and $X=\mathrm{S}/\mathrm{Se}$) are of particular importance for the new-generation photovoltaic devices due to their special in-plane spontaneous polarization resulting in a bulk photovoltaic effect. However, the spontaneous polarization and its related dynamical photoresponse under an ultrafast laser excitation are rarely studied via a noncontact all-optical method. Herein, the vertically grown SnS nanosheets have been synthesized by a physical vapor deposition (PVD) method and the corresponding spontaneous polarization is characterized via the terahertz (THz) emission spectroscopy. The primary THz emission mechanism is ascribed to the shift current, which is proved by the THz wave dependences on the pump light polarization angle and pump fluence. Interestingly, the shift current depends on the spontaneous polarization along the SnS nanosheet grown direction, according to the reversed polarity of the THz wave under opposite directional excitations. Furthermore, the amplitude and phase of the THz wave are modulated by the pump light polarization angle, resulting in the elliptical THz wave emission with tunable ellipticity and orientation angle. Our study has shed light on the shift current of ferroelectrics and controllable polarized THz wave generation, which provides application prospects for ferroelectric-based photovoltaics, nonlinear photonics, and THz polarized devices.

Infrared Analysis and Effect of Nitrogen and Nitrous Oxide on the Glass Transition of Methanol Cryofilms.

Methanol plays an important role in studying the structure and dynamics of hydrogen bonds in alcohols and other physiologically important compounds in the condensed state. The physical vapor deposition method and two-beam interferometry make it possible to study the structure of polyatomic molecules, the nature and character of intermolecular interactions, and the internal structure of various compounds. Thus, it becomes possible to analyze changes in the internal structure of substances near the points of their phase transitions and glass transitions at ultralow temperatures. In this work, we have studied the effect of nitrogen and nitrous oxide on the dependence of refractive indices of methanol on temperature and on structural-phase transformations upon heating from 16 to 160 K.

Facile engineering of gold alloying on the constancy of silver with polytetrafluorethylene denture base nanomaterial for antimicrobial investigation

Herein, nanocomposites comprising Ag–Au-alloy-based nanomaterials ensembled on the polytetrafluoroethylene (PTFE) were fabricated using the physical vapor deposition method. The Ag-based nanomaterials (AgNMs) undergo oxidation and dissolution in water; therefore, changes in the shape, optical characteristics, and composition of the nanocomposites were investigated through transmission electron microscopy, ultraviolet-visible spectroscopy, and X-ray photoelectron spectroscopy. PTFE@Ag–Au coatings exhibited high antibiofilm efficacy against E. coli WT F1693 and governed the synergistic effect of antibacterial non-stick PTFE and the Ag–Au alloy. The PTFE@Ag–Au-coated NMs sustained the release of Ag+ ions and inhibited up to 50% bacterial growth after 7 days in relation to the PTFE-coated NMs. The conventional XDLVO and DLVO theories were used to describe bacterial adhesion and understand the anti-adhesion process. Despite concerns associated with the hazardous effect of excessive Ag release on fibroblast cells, the coating methods precisely controlled Ag loading, thereby reducing metallic-implant-related bacterial infections.

Facile fabrication of multifunctional transparent electrodes via spray deposition of indium-tin-oxide nanoparticles

Low-dimensional nanomaterials with various functionalities are highly promising materials for transparent electrodes which are key components of electronic and optoelectronic devices. However, conventional physical vapor deposition (PVD) methods are not applicable to low-dimensional nanomaterials because of the harsh vaporizing conditions, and using solution processing technologies as alternatives is attracting attention. Herein, we demonstrate a facile method for fabricating of multifunctional transparent electrodes via one-step spray deposition of indium-tin-oxide (ITO) nanoparticles. In this method, ITO nanoparticles are spontaneously and rapidly packed, forming electrically conductive thin films composed of random nanostructures. This method can be adapted to fabricating hierarchical structures, that is, micropatterns consisting of random nanostructures, using impermeable shadow masks. In addition, the optical and electrochemical properties of the spray-deposited ITO films were investigated to confirm their high transmission haze values and ion-storage capabilities, leading to further applications such as random scattering layers, transparent superconductors, and high-performance electrochromic devices. We expect these results to spur the development and refinement of multifunctional electrodes and their electronic and optoelectronic applications.

Solar and infrared light sensing comparison of Yb/CIGS photodiode

Glass/Mo/CIGS/Yb Schottky photodiodes were fabricated by the physical vapor deposition method. The structural and morphological characterization of the CIGS layer on Mo was carried out. The current-voltage ( I-V ) characteristics were investigated in the dark, under solar light, and infrared. The diodes' ideality factor and zero bias barrier height were calculated as 1.55 and 0.84 eV in the dark, respectively. When the time-dependent current plots are examined, it is seen that the rise and decay times are lower for solar light than infrared. As the intensity of solar light increases, the rise and decay times decrease. The responsivity value for 100 mW/cm 2 solar light was found to be 8.5 mA/W and the detectivity value was 1.7 × 10 7 Jones. For infrared light, the same parameters were calculated as 3.4 mA/W and 7.1 × 10 6 Jones. Furthermore, capacitance-voltage and conductance-voltage characteristics were evaluated for different frequencies. • Yb/CIGS photosensor was produced on bi-layer Mo layer. • Switch ON−OFF time was maintained at 5 s • I-t and C-t measurements taken at different solar light intesities (from 20 to 100 mW/cm 2 ) and infrared (100 mW/cm 2 ). • Responsivity and detectivity parameters were calculated. • Frequency−dependent C-V and G-V characteristics investigated.

A novel nanoporous Mg-Li material for efficient hydrogen generation

• Nanoporous Mg-Li material is successfully prepared for the first time. • This material can deliver 962 ml g −1 H 2 in 15 min at 0 °C and in 3 min at 50 °C. • The advances come from the nanoporous structure and the addition of li element. • The growth mechanism of the nanoporous Mg-Li material is proposed. Hydrogen generation material is a new kind of energy material that can supply hydrogen by reacting with water and is drawing more and more attention with the development of hydrogen economy. In this study, a novel nanoporous magnesium-lithium material prepared by a physical vapor deposition method exhibits an excellent hydrogen generation property. It generates hydrogen efficiently and quickly with saltwater, reaching a hydrogen generation amount of 962 mL g −1 and hydrogen generation rates of 60 mL g −1 min −1 , 109 mL g −1 min −1 , 256 mL g −1 min −1 and 367 mL g −1 min −1 at 0 °C, 25 °C, 35 °C and 50 °C, respectively. The nanoporous magnesium-lithium material is composed of a solid solution phase with a magnesium-lithium atomic ratio of 17:3. By synchrotron radiation analysis, the sizes of the nanopores are in the range of 100 nm ∼ 600 nm with an average size of 280 nm, and the porosity is calculated to be ∼42.4%. The improved hydrogen generation property is attributed to the nanoporous structure with a high specific surface area, and the addition of lithium element which acts as active sites in hydrogen generation process.

Growth mechanism of nano-plates structured SnS films on different substrates in glancing angle deposition method

In this work, Tin (II) sulfide films have been deposited on glass, Indium Tin Oxide, and Fluorinated Tin Oxide substrates at the deposition angles of 0º, 65º, and 85º using Physical Vapor Deposition method equipped with Glancing Angle Deposition technique. Based on the results obtained from the X-ray diffraction technique, the crystalline structure of substrates and the angle of depositions along with their effects on the structure of SnS nano-plates have been investigated. Using Raman analysis, the phonons lifetime of the samples was found to change with the type of substrate and the employed deposition angle. Based Energy-dispersive X-ray spectroscopy analysis, the atomic ratio of Sn to S was observed to change with the change of deposition angle, substrate type and variation the diameter of nano-plates. This phenomenon resulted the formation of the second phase of Sn2S3 which was confirmed by Raman and X-ray diffraction patterns. The nano-sheets-like growth of all the samples has been confirmed using Felid Emission Scanning Electron Microscopy analysis. For further morphological studies, the Atomic Force Microscopy analysis has been applied, by which the direct relation between the substrate roughness and the final structure of the samples has been observed. The relation between the substrate roughness and the deposition angle in the growth process of SnS nano-sheets has been explained.

Analysis of TihxOy Films Produced by Physical Vapor Deposition Method

For decades, partially oxidized hydrides were commonly considered as undesirably contaminated phases and were avoided by scientists. Nevertheless, more recently, it was realized that in some hydrides and oxides, partial substitution of dissimilar H− and O2− anions allows one to obtain unique optical and electrical properties that might have appealing applications in commercial products. It was determined that specific properties of so called oxyhydride materials strongly depend on the used synthesis methods; therefore, there is a great interest in exploring various variants of oxyhydride formation. In the current study, TiHxOy films were deposited by a reactive magnetron sputtering process in Ar-O2-H2 gas mixtures. Color, transparency and crystal phase composition of the films coherently reacted to the Ar:O2:H2 gas ratio. Namely, the rise in partial hydrogen pressure promoted the formation of anatase phase TiO2 structure and darkening of the films. Interestingly, this had only minimal impact on the band gap values, but had a relatively strong negative effect on the photocatalytic activity of the films. The unaccustomed results stressed the difference between the partially reduced TiO2 with a significant amount of oxygen vacancies and synthesized TiHxOy films where some O2− ions are implicitly substituted by H− ions.

Optical Studies of Thin Films of Cryocondensed Mixtures of Water and Admixture of Nitrogen and Argon.

The interaction of host molecules with water molecules is of primary importance in astrophysical and atmospheric studies. Water-binding interactions continue to attract a broad interest in various fields, especially those related to the formation of assembly structures. Using the physical vapor deposition (PVD) method and a two-beam interferometer with a wavelength of 406 nm, the refractive indices of thin films of a water and nitrogen (argon) mixture were calculated in the range from 15 to 35 K. The results of temperature transformations of the obtained films from a two-beam interferometer, and thermal desorption characteristics from the temperature of condensation to the temperature of evaporation of water (15-180 K), are presented. The relationship between the signal of the interferometer, the refractive index, and the film thickness during glass transition is demonstrated.