Physical Vapor Deposition Research Articles

Microstructure, mechanical properties, and wear behaviors of CrSiN films on oxynitriding-treated Vanadis 60 high-speed steel by the direct current magnetron sputtering process

This study utilized the direct current magnetron sputtering technique within the physical vapor deposition process to apply a chrome silicon nitride (CrSiN) coating onto the oxynitrided surface of Vanadis 60 high-speed steel. The experimental parameters include various deposition bias voltages (0, -25, -50, -75, and -100 V), a gas flow rate of 45/30 (Ar/N2) sccm, a power of 100 W, a voltage of 400 V, a deposition time of 2.5 h, and a deposition temperature of 225 °C. The research results show that the substrate formed an oxynitriding layer with a thickness of about 30 μm, while the surface hardness increased to about 1300 HV0.05. When the coatings were deposited at a bias voltage of -100 V, the CrSiN coatings possessed the highest hardness (5.74 GPa) and elastic modulus (110.94 GPa), thus, it had the best wear resistance (specific wear rate was 1.19×10−5, and 7.29×10−5 mm3·m−1·N−1 under the loads of 1.5 N and 3 N), and good corrosion resistance (corrosion current was 3.28×10−5 A·cm−2, and polarization resistance was 793.18 Ω·cm2 in a 0.1 N H2SO4 solution). Furthermore, transmission electron microscopy observations confirm that the CrSiN coatings had a significant amorphous structure.

Effect of molecular permanent dipole moment on guest aggregation and exciton quenching in phosphorescent organic light emitting diodes.

This study explores the effect of molecular permanent dipole moment (PDM) on aggregation of guest molecules in phosphorescent host-guest organic light-emitting diodes (OLEDs). Through a combination of photoluminescence measurements, high-angle annular dark-field scanning transmission electron microscopy analysis, and an Ising model based physical vapor-deposition simulation, we show that higher PDM of tris[2-phenylpyridinato-C2,N]iridium(III) guest can actually lead to a reduced aggregation relative to tris[bis[2-(2-pyridinyl-N)phenyl-C] (acetylacetonato)iridium(III) when doped into a non-polar host 1,3,5-tris(carbazol-9-yl)benzene. This study further explores the effect of host polarity by using a polar host 3',5'-di(carbazol-9-yl)-[1,1'-biphenyl]-3,5-dicarbonitrile, and it is shown that the polar host leads to reduced guest aggregation. This study provides a comprehensive understanding of the impact of molecular PDM on OLED material efficiency and stability, providing insights for optimizing phosphorescent OLED materials.

Fabrication and characterization of MgF2 anti-reflective films comprising dual-layer prepared by physical vapor deposition technique for optoelectronic applications

Moth eye protuberances, for instance, exhibit highly developed and well-organized nanostructures that allow them to adapt to a wide range of environmental conditions and achieve remarkable antireflective performance, which has inspired and been emulated by scientific advancement. Innovative studies have focused on bioinspired and imitating moth-eye patterns to provide a textured surface in multilayer antireflective coatings (ARC) using nanomaterials, polymers, or composites to eliminate undesired reflection in standard optical components and optoelectronic industrial applications. Multilayer AR systems provide a number of advantages over single-layer designs. Still, their limited applicability is due to obstacles such as mismatched properties at interfaces, high costs, poor mechanical durability, and wetting concerns. Using MgF2 and polytetrafluoroethylene, we develop a technique for fabricating high-performance AR nanostructures on borosilicate crown glass and Fluorine-doped Tin Oxide substrates via the glancing angle deposition technique. By inducing porosity and changing the deposition angle (α) at 550 nm, the refractive index of MgF2 is reduced from 1.38 to 1.14. In agreement with optical modelling predictions, high-performance ARC has been successfully produced on different substrates. Besides this, introducing a thin layer of polytetrafluoroethylene on MgF2 ARC via vapor deposition having a refractive index of 1.21 deposited at α ∼80° results in inducing water-repellent properties in ARC. Hence, our fabricated ARC yields stable AR efficiency with outstanding directional uniformity, durability, and negative temperature stability, having hydrophobic characteristics.

Stripping process of TiAlN/TiSiN coating on WC-Co cemented carbide substrate by using the dry-electropolishing technique

Physical Vapor Deposition hard protective coatings are frequently applied to hardmetal cutting tools to extend their lifespan under service-like working conditions. However, these coatings may experience damage during their performance, such as wear. In addition, defective coatings during the production process can occur, requiring reconditioning. In this sense, provided that the coating has not chipped off, removing and recoating the tools is a crucial process for their reuse, ultimately reducing costs. This study investigates the stripping process of an industrial ternary system (TiAlN/TiSiN) coating deposited on WC-Co cemented carbide using the dry-electropolishing technique. X-ray photoelectron spectroscopy was used to analyze the electrochemical surface changes. Chemical analysis reveals that a layer of oxide is created during the stripping process, mainly composed of SiO2, TiO2, and Al2O3, as well as organic compounds (e.g.: pyrrodic group in aromatics C-(NH)-C) and nitrogen oxides (e.g.: pyrinidic O=N-C). The stripping process successfully removed the coating without damaging the WC-Co substrate or leaching metallic Co binder. Additionally, the process follows a linear trend, establishing a correlation between the time of dry-electropolishing applied and the remaining coating thickness.

Exploring the structural, photophysical, and electrical properties of Dopant-Free hole transporting material based on 2, 7-carbazole from experimental to simulation

This paper presents the development of a dopant-free HTM as a thin film, utilizing carbazole (2,7) as a central building block. The deposition of homogeneous thin films of HTM2 was successfully achieved through Physical Vapor Deposition. The morphological, optical, and electrical properties of the fabricated samples were extensively studied using techniques such as Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), UV–visible spectroscopy, and Photoluminescence Technique. The AFM and SEM analyses demonstrated the uniformity and flatness of the thin film surfaces. The UV spectra results indicated that the maximum absorption spectra did not exhibit significant shifts when measured in chlorobenzene solvent, with an estimated band gap of approximately 2.96 eV. Photoluminescence spectroscopy and decay time measurements were conducted on HTM2 thin films, which revealed emission in the green-yellow region. The photoluminescence spectra of the thin films exhibited red-shifted emission bands compared to the solution, attributable to stronger π-π intermolecular interactions resulting in the closeness of the molecules in the solid state. This work finally couples the theoretical and experimental results to validate our obtained results and to get an idea about the efficiency of the cell-based HTM2. The obtained results confirmed that the investigated material can find applications in perovskite solar cells.

Investigation of an electrode-driven hydrogen plasma method for in situ cleaning of tin-based contamination

To prolong the service life of optics, the feasibility of in situ cleaning of the multilayer mirror (MLM) of tin and its oxidized contamination was investigated using hydrogen plasma at different power levels. Granular tin-based contamination consisting of micro- and macroparticles was deposited on silicon via physical vapor deposition (PVD). The electrode-driven hydrogen plasma at different power levels was systematically diagnosed using a Langmuir probe and a retarding field ion energy analyzer (RFEA). Moreover, the magnitude of the self-biasing voltage was measured at different power levels, and the peak ion energy was corrected for the difference between the RFEA measurements and the self-biasing voltage ( ). XPS analysis of O 1s and Sn 3d peaks demonstrated the chemical reduction process after 1 W cleaning. Analysis of surface and cross-section morphology revealed that holes emerged on the upper part of the macroparticles while its bottom remained smooth. Hills and folds appeared on the upper part of the microparticles, confirming the top-down cleaning mode with hydrogen plasma. This study provides an in situ electrode-driven hydrogen plasma etching process for tin-based contamination and will provide meaningful guidance for understanding the chemical mechanism of reduction and etching.

A Dopamine Detection Sensor Based on Au-Decorated NiS2 and Its Medical Application.

This article reports a simple hydrothermal method for synthesizing nickel disulfide (NiS2) on the surface of fluorine-doped tin oxide (FTO) glass, followed by the deposition of 5 nm Au nanoparticles on the electrode surface by physical vapor deposition. This process ensures the uniform distribution of Au nanoparticles on the NiS2 surface to enhance its conductivity. Finally, an Au@NiS2-FTO electrochemical biosensor is obtained for the detection of dopamine (DA). The composite material is characterized using transmission electron microscopy (TEM), UV-Vis spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The electrochemical properties of the sensor are investigated using cyclic voltammetry (CV), differential pulse voltammetry (DPV), and time current curves in a 0.1 M PBS solution (pH = 7.3). In the detection of DA, Au@NiS2-FTO exhibits a wide linear detection range (0.1~1000 μM), low detection limit (1 nM), and fast response time (0.1 s). After the addition of interfering substances, such as glucose, L-ascorbic acid, uric acid, CaCl2, NaCl, and KCl, the electrode potential remains relatively unchanged, demonstrating its strong anti-interference capability. It also demonstrates strong sensitivity and reproducibility. The obtained Au@NiS2-FTO provides a simple and easy-to-operate example for constructing nanometer catalysts with enzyme-like properties. These results provide a promising method utilizing Au coating to enhance the conductivity of transition metal sulfides.

Microstructural characterization of nanocrystalline hexagonal boron nitride thin films deposited by ion-beam assisted pulsed laser deposition

In recent years, hexagonal boron nitride (hBN) thin films have garnered considerable attention across various fields, including electronics, anti-corrosion coatings, tribology, and optoelectronics. Boron nitride films produced via physical vapor deposition typically result in amorphous microstructure and suffer from issues such as cracking and delamination. The synthesis of crystalline hBN thin films typically demands higher processing temperatures, toxic gas precursors, and catalytic metal substrates. Hence, this research aims to produce crystalline hBN films at relatively lower temperatures without toxic gas precursors. hBN thin films were deposited on silicon (100) substrates at 600 °C using an ion beam-assisted pulsed laser deposition. The study explores the microstructural evolution and surface morphology of deposited films under different Ar:N2 gas mixtures (ranging from 0% to 100% N2) and varying ion beam energies (from 0 to 400 eV). Microstructural analysis showed the hBN nanocrystallite formation in films deposited with N2 content of 50% and higher and an ion beam energy equal to or exceeding 200 eV, and the crystallite size was measured to be ∼24±8 nm. Raman spectra, grazing incidence X-ray diffraction, and transmission electron microscopy confirm the presence of hBN phase in as-deposited films. Films deposited with an N2 content of ≥50% and ion beam energy of ≥200 eV showed improved crystallinity, increased island size, and density of hBN nanocrystallites. The addition of ion bombardment comparatively made films rougher due to grain growth and formation of larger hBN nanoislands, and surface roughness increased with an increase in N2 content and ion beam energy. The results indicate that the ion beam bombardment facilitates nanograin formation and improves the crystallinity of hBN films even at lower deposition temperatures, offering the promise of advancing their use into practical applications across various fields.

The Influence of Temperature on the Photoelectric Properties of GeSe Nanowires.

Using physical vapor deposition (PVD) technology, GeSe nanowires were successfully fabricated by heating GeSe powder at temperatures of 500 °C, 530 °C, 560 °C, 590 °C, and 620 °C. The microstructure, crystal morphology, and chemical composition of the resulting materials were thoroughly analyzed employing methods like Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), plus Raman Spectroscopy. Through a series of photoelectric performance tests, it was discovered that the GeSe nanowires prepared at 560 °C exhibited superior properties. These nanowires not only possessed high crystalline quality but also featured uniform diameters, demonstrating excellent consistency. Under illumination at 780 nm, the GeSe nanowires prepared at this temperature showed higher dark current, photocurrent, and photoresponsivity compared to samples prepared at other temperatures. These results indicate that GeSe nanomaterials hold substantial potential in the field of photodetection. Particularly in the visible light spectrum, GeSe nanomaterials exhibit outstanding light absorption capabilities and photoresponse.

Silver Decoration of Vertically Aligned MoS2-MoOx Nanosheets: A Comprehensive XPS Investigation.

This study investigates the simultaneous decoration of vertically aligned molybdenum disulfide nanostructure (VA-MoS2) with Ag nanoparticles (NPs) and nitrogen functionalization. Nitrogen functionalization was achieved through physical vapor deposition (PVD) DC-magnetron sputtering using nitrogen as a reactive gas, aiming to induce p-type behavior in MoS2. The utilization of reactive sputtering resulted in the growth of three-dimensional silver structures on the surface of MoS2, promoting the formation of silver nanoparticles. A comprehensive characterization was conducted to assess surface modifications and analyze chemical and structural changes. X-ray photoelectron spectroscopy (XPS) showed the presence of silver on the MoS2 surface. Scanning electron microscopy (SEM) confirmed successful decoration with silver nanoparticles, showing that deposition time affects the size and distribution of the silver on the MoS2 surface.

Optical Properties of Gallium Nitride Heterostructures Grown on Quartz Using Pulse Laser Deposition Method

An optical analysis was conducted on a Gallium nitride (GaN) thin film grown on a quartz substrate using the physical vapor deposition technique (PVD), specifically, pulsed laser deposition (PLD). The film was grown using different laser wavelengths (1064, 532, and 355) nm from a Q-switch neodymium-doped yttrium aluminum garnet (Nd: YAG) laser, all performed under a vacuum pressure of 10-2 m bar. The absorption coefficient of the GaN thin film was determined by performing UV-Vis diffused spectroscopy at room temperature and measuring wavelengths ranging from 200 to 1000 nm. The absorption peak occurs at 227 nm when the wavelength is 1064 nm, at 217 nm when the wavelength is 532 nm, and at 222 nm when the wavelength is 355 nm. The optical energy gap is a crucial statistic for analyzing the properties of thin films and assessing their potential as gas sensors. The value of the direct energy gap (Eg) for the prepared films was established by analyzing the graph that shows the relationship between (α h) and the energy gap (ev) values at different wavelengths. The energy values were determined to be 3.36 eV, 3.62 eV, and 3.7 eV for 1064, 532, and 355 nm wavelengths, respectively.

Self-organized composite morphologies and interface instability of immiscible alloy thin films during physical vapor deposition: Insights from phase-field simulations

In this paper, we carried out phase-field simulations for investigating self-organized composite morphologies formation and interface instability of two phase immiscible binary alloy thin-film growth during physical vapor deposition. Predicted results show that for lower the deposition rate the solid-gas interface keeps planar and the lateral composition modulation (LCM) configuration occurs. As the deposition rate increases, the self-organized composite morphology gradually transfers to vertical composition modulations (VCM) configuration and the random composition modulations (RCM) configuration with the decrease of the boundary layer of the incident vapor and the unsteady solid-gas interface. Results show that the nanoprecipitate concentration modulation (NCPM) depends strongly on the nominally phase fraction. Moreover, we found that the historical dependence of self-organized composite morphologies and solid-gas interface stability, i.e., the initial condition can strongly influence the microstructure of the thin film during physical vapor deposition. Finally, we provide an analysis method for interface instability based on fast Fourier transform (FFT), and the frequency characteristics of cellular and bump structures are identified.

A fibrous Ir-doped NiFeOx on two-dimensional materials for high efficiency oxygen evolution reaction (OER)

As a clean and renewable energy, hydrogen gas can be generated from water electrolysis which also involves the sluggish oxygen evolution reaction (OER). The main commercial catalysts for OER are Ir and Ru based but have the problems of high cost and poor cycling stability. Herein, we designed a new electrocatalyst based on Ni, Fe and Ir compounds loaded on a unique two-dimensional carbon material, which can efficiently catalyze OER with high stability in alkaline solution. The composite was prepared by physical vapor deposition, showing a fibrous microscopic morphology with uniform particle size distribution. The fibrous structure ensured the exposure of active sites, which further improved OER activity. The loading of metallic iridium in the material is only 0.0858 mg cm−2. The catalytic activity of OER was maintained for 54 h under alkaline conditions at a current density of 50 mA cm−2 without significant changes in current density. Characterization showed that the excellent activity and stability of the catalysts originated from the Ir insertion into the NiFe2O4 lattice.

Effects of PVD CrAlN/(CrAlB)N/CrAlN Coating on Pin–Disc Friction Properties of Ti2AlNb Alloys Compared to WC/Co Carbide at Evaluated Temperatures

Physical vapor deposition (PVD) coatings could affect the friction performance at the contact interface between Ti2AlNb alloy parts and tool couples. Suitable coating types could improve the friction properties of Ti2AlNb alloy while in contact with WC/Co carbide. In this study, the linear reciprocating pin–disc friction tests between the Ti2AlNb alloy and the WC/Co carbide tool couple, with the sole variation of the PVD CrAlN/(CrAlB)N/CrAlN coating were conducted within the temperature range of 25–600 °C. The antifriction properties of the Ti2AlNb alloy were estimated using the time-varied friction coefficients, the alloy wear rate, worn surface topography, worn surface element, and wear mechanism analysis. The results showed that the PVD CrAlN/(CrAlB)N/CrAlN coating could decrease the average friction coefficient and alloy wear rate compared to the uncoated WC/Co carbide couple. The apparent adhesive wear and abrasive wear of the Ti2AlNb alloy could be improved due to the PVD coating at evaluated temperatures. The PVD CrAlN/(CrAlB)N/CrAlN coating could be utilized to improve the antifriction properties of the Ti2AlNb alloy, which may be deposited on the cutting tool to improve the machining performance of Ti2AlNb alloys in future aerospace machining industry.

Process Development of Aluminum Electroplating from an Ionic Liquid on 150 mm Wafer Level.

This paper focuses on the development of electroplating on 150 mm wafer level for microsystem technology applications from 1-Ethyl-3-methylimidazolium chloride (EMImCl) with Aluminumtrichloride (AlCl3). The deposition was carried out on 150 mm wafers with Au or Al seed layers deposited by physical vapor deposition (PVD). The electrodeposition was carried out using pattern plating. On the Au seed layer, bipolar pulse plating was applied. Compared to the Au seed layer, the electrodeposition on the Al seed layer was favorable, with lower current densities and pulsing frequencies. Utilizing the recurrent galvanic pulses and avoiding ionic liquid convection, inhomogeneities lower than 15% were achieved with a laboratory plating cell. One major aspect of this study was the removal of the native Al oxide prior to deposition. It was investigated on the chip and wafer levels using either current- or potential-controlled removal pulses. This process step was affected by the plasma treatment of the wafer, thus the surface free energy, prior to plating. It turned out that a higher surface free energy hindered proper oxide removal at a potential of 3 V. The theory of oxide breakdown based on electrostriction force via the electrical field was applied to discuss the findings and to derive conclusions for future plating experiments.

Protective layers of zirconium alloys used for claddings to improve the corrosion resistance

Abstract Zirconium alloys are used as a cladding material for fuel elements in nuclear reactors. In the case of severe accident conditions, the possible rapid oxidation of zirconium in steam or/and air may result in intense hydrogen generation and hydrogen–oxide mixture explosion. Advanced technologies for increasing the corrosion resistance of claddings are being investigated in two directions: (a) protective coatings on Zr alloys and (b) the use of new materials for claddings. Coatings with silicon may provide a more protective barrier than the ZrO2 films formed on an alloy cladding during nuclear plant operations. These coatings may also serve as a protective barrier during high-temperature accidents. The current work aimed at developing protective coatings with silicon on zirconium alloys. Multielemental Zr–Si–Cr coatings were formed on Zry-2 alloy using the physical vapor deposition (PVD) method. Long-term oxidation tests were carried out under the following conditions: 360°C/195 bar/63 days/water-simulating PWR water. Obtained results show the protective character of formed layers. The material in the form of silicon carbide grains covered with yttrium–aluminum garnet (SiC + YAG) was prepared using the sol–gel method. The formed powder is the main component for coating formation on Zr–1Nb alloy using the method of suspension plasma spraying (SPS).

Design and fabrication of a fast-response and low-energy input micro igniter

In this study, we innovatively combine direct ink writing (DIW) and physical vapor deposition (PVD) to fabricate a novel micro igniter with fast-response and low-energy input characteristics. The igniter comprises a 5×5 mm² metal film bridge with gold contact pads. The metallic resistance is fabricated using a series of photolithography, metal deposition, and lift-off processes. After evaluating titanium and chromium as the resistive filament, titanium was selected due to its superior reactivity when in contact with CuO leading to reduced ignition energy. Onto the resistive titanium layer, either thermite multilayer films and/or energetic inks are deposited to achieve a head-to-head comparison of ignition characteristics. We show that igniters powered by (CuO/Ti)5 bilayers and Al/CuO/PVDF as energetic ink demonstrate the equivalent ignition performance as reactive (CuO/Ti)5 multilayered igniter. The ignition delay and ignition energy are below 1 ms and 2 mJ, respectively, while the flash intensity is approximately one decade higher than what is typically achieved with conventional micro-igniters. Furthermore, its ignition behaviour can be readily adjusted by altering the constituents of the fuel/oxidizer or adjusting the ratio of multilayer/inks, thereby allowing for easy adaptation of the micro-igniter to meet the diverse requirements of various applications.

Electrical properties and field emission characteristics of ITO nanorod thin films synthesized by electron beam physical vapor deposition

Electrical properties and field emission characteristics of ITO nanorod thin films synthesized by electron beam physical vapor deposition

Development of an electrochemical biosensor with TiN nano-electrode arrays for IL-6 detection

In this study, we developed a novel electrochemical biosensor for detecting IL-6 that uses a nano-electrode array (NEA) fabricated via standard CMOS processing. Miniaturizing the electrodes to the nanoscale and arranging them in an array to form an NEA facilitated the creation of a higher electric field magnitude, compared to that available via the use of microelectrodes, that could be used to improve biosensor sensitivity. Additionally, the array configuration of the NEA aided in providing sufficient reaction sites. Each nano-electrode in the NEA was cylindrically shaped, with a radius of 0.1 µm, and a top layer formed by TiN physical vapor deposition. Each NEA biosensor was divided into four independent banks, with each bank including a set of WE, CE and RE. These banks were capable of independently inputting and outputting electrical signals. This design allowed the NEA biosensor to undergo selective modification by CV input. In this study, we discuss and address material and contamination issues associated with CMOS-produced NEAs and their uses as biosensors. To ameliorate these issues, we stored materials and products in a nitrogen-controlled cabinet and conducted pretreatment cleaning on the electrodes. Both steps had a noticeable impact on the cleanliness of the electrode surfaces. These optimized conditions resulted in a remarkable 96.6 % reduction in Rct. The NEA surface was functionalized by electrochemically grafting diazonium salts subsequently immobilized with anti-IL-6 antibodies via EDC/NHS chemistry. The resulting NEA biosensor demonstrated sufficient sensitivity to rapidly distinguish inflammatory conditions and disease severity. This showcases the potential for using NEA devices mass-produced via standard CMOS processing as electrodes for biosensors.

Microstructure evolution of carbon films, grown by physical vapor deposition, when substrate temperature is increased

We study how the increases of substrate temperature influence the structural properties of carbon films deposited by physical vapor deposition (PVD) techniques. We installed and adapted a heating system inside the deposition chamber, which can reach temperatures as high as 700 °C. Here we develop an experimental setup that allows us to obtain large films of the desired material on any substrate, with deposition times of the order of a minute. The characterization is based mainly on the analysis of the Raman spectra, where the evolution of the G and D peaks corresponding to the material in its amorphous phase is observed. With the increase of substrate temperature, the sp2 zones grow. A displacement to the right of the G peak and an increase in the ID/IG ratio is seen. At 700 °C a 2D zone at a frequency greater than 2000 cm−1 appears. Four Lorentzian-shaped bands are necessary to account for the peaks at this zone, whose centers correspond to different combinations of first-order ones. This shows that we are transitioning from an amorphous to a carbon phase with more ordered or graphitic zones and that we are near the crystallization point. This opens the path to produce structures similar to graphene using this method of deposition. The Tauc gap energy ratio decreases as temperature increases indicating that there is a graphitization of the sample. Transmission FTIR study is carried out at some of the intermediate temperatures, determining the type of bond at low frequencies. These bonds are consistent with the ones of the hydrogenated amorphous carbon (a-C:H) structure.