Physical Vapor Deposition Process Research Articles

Antibacterial Food Packaging Containing Stably Dispersed Cu Nanoparticles Synthesized by Novel Physical Vapor Deposition Process

Polymeric materials were modified by nanoparticles on powder (NPP) facility in which metal nanoparticles (Cu, Cu/Zn alloy etc.) are formed on the surface of rotating carrier powder by using physical vapor deposition process untile the metal content reached 0.3wt.%. The polymer material with metal nanoparticles deposited on their surface through the NPP process was then added to the raw polymer material at a ratio of 1 to 9. The mixture of modified polymer powder and raw polymer powder were then processd into a film by conventional processes such as hot melting, extrusion, T-die, and antibacterial characteristics of the film were investigated. We ultimately manufactured antibacterial food package using the film and conducted preservation test for two weeks at room temperature. Since food package containing 0.03wt.% Cu nanoparticles showed over 99.9% bacteria reduction rate, it slowed down the progress of deterioration significantly compared to conventional packages. For safety evaluation, the amount of copper released out was analyzed and a cytotoxicity test was also conducted.

Antibacterial Food Packaging Containing Stably Dispersed Cu Nanoparticles Synthesized by Novel Physical Vapor Deposition Process

Antibacterial Food Packaging Containing Stably Dispersed Cu Nanoparticles Synthesized by Novel Physical Vapor Deposition Process

Electrochemical Performance of Boron- and Nitrogen-Doped Tetrahedral Amorphous Carbon

Tetrahedral amorphous carbon (ta-C) is one of the most versatile carbon electrode materials available. The incorporation of various dopants in ta-C alters the structural, electrochemical, physical, and chemical properties which are tunable for various applications. Furthermore, doped ta-C (ta-C:X) can be deposited on many different substrate materials (metals, ceramics, plastics) and geometries (micro-electrodes to ultra large areas at continuous coating lines). In this work, we present a comparison in electrochemical performance of ta-C electrodes prepared by filtered laser-arc (a physical vapor deposition process), doped with nitrogen (ta-C:N) at various levels, doped by boron (ta-C:B), and doped by boron and nitrogen together (ta-C:B:N). The ta-C:N films were doped via N2 gas in the deposition chamber, while ta-C:B and ta-C:B:N were deposited via incorporation of the dopant into the graphite cathode used for film synthesis. Films coated on silicon (Si) and titanium (Ti) substrates were compared through cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The Fe(CN)63-/4− and Ru(NH3)63+/2+ redox systems were used to investigate the electrochemical characteristics of each ta-C:X film type. Boron-doped diamond (BDD), glassy carbon (GC), and undoped ta-C were used as control electrodes. It was found that all ta-C:X films exhibited appropriate rates of electron transfer, wide working potential window (ca. 3.7 V in KCl), and low capacitance. Specifically, the boronated films produced high heterogenous rate constant (k), the lowest double layer capacitance (Cdl), and a consequentially smaller RC time constant than BDD and GC. Incorporating boron into undoped and nitrogenated ta-C films stabilizes the formation of sp3 bonded content during deposition leading to films with a smoother surface and increased hardness. It is shown that the B-incorporated films exhibit no compromise in their electrochemical performance despite the increase in sp3 content. Due to its versatile nature, ta-C stands out as a material with a wide range of tunable properties for various applications.

Implementation of Numerical Model for Prediction of Temperature Distribution for Metallic-Coated Firefighter Protective Clothing

The aim of this study is to predict the distribution of temperature at various positions on silver-coated firefighter protective clothing when subjected to external radiant heat flux. This will be helpful in the determination of thermal protective performance. Firefighter clothing consists of three layers, i.e., the outer shell, moisture barrier and thermal liner. The outer shell is the exposed surface, which was coated with silver particles through a physical vapor deposition process called magnetron sputtering. Afterwards, these uncoated and silver-coated samples were exposed to radiant heat transmission equipment at 10 kW/m2 as per the ISO 6942 standard. Silver-coated samples displayed better thermal protective performance as the rate of temperature rise in silver-coated samples slowed. Later, a numerical approach was employed, contemplating the impact of metallic coating on the exterior shell. The finite difference method was utilized for solving partial differential equations and the implicit method was employed to discretize the partial differential equations. The numerical model displayed a good prediction of the distribution of temperature at different nodes with respect to time. The comparison of time vs. temperature graphs at different nodes for uncoated and silver-coated samples acquired from numerical solutions showed similar patterns, as witnessed in the experimental results.

Stable DC vacuum arc plasma generation from a 100 mm TiB2 cathode

Titanium diboride exhibits outstanding properties for hard and wear resistant coatings. However, efficient physical vapor deposition (PVD) processing through DC vacuum arc, with a deposition rate unreachable for any other PVD technique, is comparatively unexplored for TiB2 thin films due to challenges associated with the film synthesis process. In this work, we used an industrial scale arc plasma source having a plane cathode of 100 mm in diameter and a permanent magnet on its back side. We present analysis of the cathode surface, plasma generation/composition, as well as analysis of collected macroparticles. The cathode weight loss and the amount of generated macroparticles were measured as a function of process parameters (arc current and pressure, in both Ar and N2 gas). Plasma analysis shows average ion energies around 120 and 25 eV for Ti and B, respectively, and plasma ion composition of approximately 50 % Ti and 50 % B. The cathode weight loss was around 0.3–0.5 g/min, of which at least 25 % is estimated to be macroparticles. Notably, the intensity of the macroparticle generation was reduced with an increase in N2 pressure. Altogether, the results show a stable and reproducible plasma generation process and a high potential for the use of the cathodic arc as an efficient and useful method for deposition of metal borides.

Sequentially PVD‐Grown Indium and Gallium Selenides Under Compositional and Layer Thickness Variation: Preparation, Structural and Optical Characterization

AbstractGroup IIIA metal chalcogenides are an auspicious material system due to their variability of properties and hence the multitude of application options, for example, in the fields of optoelectronic, thermoelectric, piezo‐, and ferroelectric devices. Indium and gallium selenide films are innovatively grown in a sequential PVD (physical vapor deposition) process starting from metal precursor layers of various thicknesses, which are then subject to chalcogenization in different selenium contents. The resulting thin films are investigated for structural and optical properties by Raman, XRD (X‐ray diffraction), and UV–Vis–NIR spectrometry, revealing that all the compounds In2Se3, InSe, In4Se3, Ga2Se3, and GaSe as well as different polytypes can be achieved depending on the metal/chalcogen ratio. Results from Raman and XRD spectroscopy are highly consistent, and also from the optical measurements changes in absorption characteristics can be correlated. The results indicate, that by fine‐tuning the selenium content, deliberately growing ultra‐thin layers of the different indium and gallium phases will be possible, thus opening up a promising route for 2D material fabrication. Given the scalability of the fabrication method, it is highly promising for large‐scale deployment of the materials.

Highly efficient molybdenum nanostructures for solar thermophotovoltaic systems: One-step fabrication of absorber and design of selective emitter

Efficient solar energy harvesting materials or structures have become a topic of great interest in response to the ever-increasing energy demand. Refractory transition metals have been found to exhibit attractive properties in broadband absorptance, making them highly effective in solar thermophotovoltaic (STPV) systems that aim to surpass the Shockley-Queisser limit. Typically, broadband absorbers are made from hybrid materials or complex geometrical structures, which require multi-step fabrication technologies. In this study, we successfully developed a highly efficient broadband absorber based on molybdenum (Mo) nanosheets using a one-step physical vapor deposition process. The nanosheets result in the high absorber efficiencies of 96.1 % for blackbody radiation (BBR) at 5778 K and of 96.4 % for air mass (AM) 1.5 spectrum, and are insensitive to polarization and incident angle. After annealing at 1650 K for 24 h, the Mo nanosheets absorber demonstrates outstanding thermal stability without compromising the efficiency of the STPV system. To complete the STPV system, a selective narrowband Mo-based gratings emitter was further designed with a high emissivity of 96 % at a wavelength of 2.17 μm, resulting in a high PV cell efficiency of 41.8 % around 1723 K. Through a series of theoretical calculations, the proposed STPV system can achieve an overall conversion efficiency of 40.2 % by a trade-off between the structure temperature and the sun concentration. Furthermore, an efficiency of 35.5 % can be achieved at a low temperature of 1073 K with a low solar concentration of 500 suns.The results provide tremendous opportunities for widespread applications of high-performance STPV systems.

Impact of Nb and Al content in arc evaporation targets on Ti1−x−yAlxNbyN coating properties

Titanium-based physical vapor deposition (PVD) coatings, such as titanium nitride (TiN) and titanium niobium nitride (TiNbN), are common solutions for surface modifications in medical applications. Ex vivo studies of retrieved knee implants indicate the demand for increased scratch and abrasion resistance of PVD coatings in clinical applications. Based on the promising mechanical performance of titanium aluminum nitride (TiAlN) as a coating for tools, the aim of this study was to evaluate the impact of the chemical composition of titanium-based nitride coatings with aluminum (Al) and niobium (Nb). Nine titanium aluminum niobium nitride (Ti1−x−yAlxNbyN) coatings with 0.4 ≤ x < 0.7 and 0 ≤ y ≤ 0.18, as well as commercial TiN and TiNbN, were coated in an industrial scale arc PVD process, following a randomized, multifactorial response surface design. The deposition rate, the scratch resistance, and the hardness were measured following standardized protocols. The microstructure of the coating was analyzed by SEM and XRD. In addition, the surface roughness was determined by laser scanning microscopy. A quadratic regression was performed to determine the impact of the chemical composition on coating properties. Experimental results and regression analyses revealed the significant impact of the chemical composition of Ti1−x−yAlxNbyN on the coating microstructure, mechanics, and morphology. Scratch resistance for initial crack formation and cohesive failure could be increased decisively, compared to TiN.

Wafer-Recyclable, Eco-Friendly, and Multiscale Dry Transfer Printing by Transferable Photoresist for Flexible Epidermal Electronics.

Flexible electronics have been of great interest in the past few decades for their wide-ranging applications in health monitoring, human-machine interaction, artificial intelligence, and biomedical engineering. Currently, transfer printing is a popular technology for flexible electronics manufacturing. However, typical sacrificial intermediate layer-based transfer printing through chemical reactions results in a series of challenges, such as time consumption and interface incompatibility. In this paper, we have developed a time-saving, wafer-recyclable, eco-friendly, and multiscale transfer printing method by using a stable transferable photoresist. Demonstration of photoresist with various, high-resolution, and multiscale patterns from the donor substrate of silicon wafer to different flexible polymer substrates without any damage is conducted using the as-developed dry transfer printing process. Notably, by utilizing the photoresist patterns as conformal masks and combining them with physical vapor deposition and dry lift-off processes, we have achieved in situ fabrication of metal patterns on flexible substrates. Furthermore, a mechanical experiment has been conducted to demonstrate the mechanism of photoresist transfer printing and dry lift-off processes. Finally, we demonstrated the application of in situ fabricated electrode devices for collecting electromyography and electrocardiogram signals. Compared to commercially available hydrogel electrodes, our electrodes exhibited higher sensitivity, greater stability, and the ability to achieve long-term health monitoring.

The strength of uncoated and coated ultra-thin flexible glass under cyclic load

<abstract> <p>Ultra-thin flexible glass with thicknesses of 100 µm or below is a substrate in the fields of optics, electronics, and semiconductors. Its brittleness is challenging in production processes like physical vapor deposition processes, especially in roll-to-roll production. In many cases, multiple geometric deformations take place and each step, like coating or cutting, influences the glass strength. By now, the relation between the strength of ultra-thin glass under quasi-static conditions and its strength under cyclic load has not been studied. Moreover, the effect of coatings has not been investigated. Both aspects are crucial to design reliable production processes. Therefore, the strength of ultra-thin glass under cyclic load was studied for uncoated and coated substrates. Two coating types were investigated: a single indium tin oxide film and a seven-layer antireflective layer stack. The coatings significantly influence the strength of the underlying glass in both test modes. The barrier properties, thin film stress, and the morphology/crystalline structure are identified as the major characteristics influencing the strength.</p> </abstract>

Topography and Nonlinear Optical Properties of Thin Films Containing Iodide-Based Hybrid Perovskites.

This article covers selected properties of organic-inorganic thin films of hybrid perovskites with the summary formulas CH3NH3MI3, where M = Pb, Cd, Ge, Sn, Zn. The paper discusses not only the history, general structure, applications of perovskites and the basics of the theory of nonlinear optics, but also the results of experimental research on their structural, spectroscopic, and nonlinear optical properties. The samples used in all presented studies were prepared in the physical vapor deposition process by using co-deposition from two independent thermal sources containing the organic and inorganic parts of individual perovskites. Ultimately, thin layers with a thickness of the order of nanometers were obtained on glass and crystalline substrates. Their structural properties were characterized by atomic force microscopy imaging. Spectroscopic tests were used to confirm the tested films' transmission quality and determine previously unknown physical parameters, such as the absorption coefficient and refractive index. Experimental results of the nonlinear optical properties were obtained by studying the second and third harmonic generation processes and using initial sample polarization in the so-called Corona poling process. The obtained experimental results allowed us to determine the second- and third-order nonlinear optical susceptibility of the tested materials.

LIOVIX® Printable Lithium Technology for Lithium Anode Manufacturing at Scale

The commercialization of lithium metal batteries requires the mass production of cost-effective thin lithium metal foil with thickness less than 30 µm. However, today’s known technologies are not yet commercially available. For example, thin lithium metal foil can be produced by hydraulic extrusion followed by a rolling process. This process usually requires a delicate balance between the pressure and tension created by both extruder and winder, so that the resulting foil is not torn or stretched, retaining all the dimensional characteristics required. This process can be extremely challenging when making lithium metal films with thickness less 20 µm due to the poor mechanical properties of lithium metal. Lithium metal foil can also be produced by physical vapor deposition (PVD). Lithium metal foil produced by PVD process are generally homogenous and have good control in thickness. However, PVD technology requires high vacuum chamber and is slow in the deposition rate, typically in the range of 0.1 to 100 nm s−1, making industrial scale of 20 µm lithium foil very challenging1.Livent has developed LIOVIX®printable lithium technology, a proprietary formulation that combines Stabilized Lithium Metal Powder (SLMP®), rheology modifiers and solvent to produce a stable suspension that can be printed on most common substrates. LIOVIX®printable lithium technology is an enabling technology that can produce thin lithium foil with thickness of 5 µm to 50 µm with no limitation in width, length and at high deposition speed. LIOVIX®enables pattern printing and can be applied to any substrate, for example a prefabricated anode, cathode, current collector, separator, and solid or polymer electrolyte. This technology enables 3D battery printing in a custom form factor shape.In this presentation, we will cover thin lithium foil manufacturing processes using standard industrial equipment and electrochemical performance results.References Acebedo, Begoña, et al. "Current Status and Future Perspective on Lithium Metal Anode Production Methods." Advanced Energy Materials (2023): 2203744.

Diamond-like films of tetrahedral amorphous carbon deposited by anodic arc evaporation of graphite

A physical vapor deposition process using anodic arc evaporation in combination with a hollow cathode arc discharge was applied to the evaporation of graphite for deposition of hydrogen-free carbon layers. The diamond-like carbon (DLC) films deposited on 100Cr6 steel substrates were investigated by nanoindentation, Raman spectrometry, FE-SEM, AFM and spectroscopic ellipsometry. The relationships between the process parameters and the coating properties are discussed. Coatings deposited without bias voltage at substrate temperatures <200 °C are very hard (61–75 GPa) with also very high Young's modulus (588–685 GPa). The evaluation of the Raman spectra indicated a high proportion of tetrahedral sp3 bonds in the range of 70–88 %. Obviously, the vapor particle energies are high enough to achieve such high hardness values even without application of a bias voltage. The coatings proved to be completely droplet-free and have a very low surface roughness as confirmed by FE-SEM and AFM. The deposition rates in the range of 4–18 nm/s are exceptionally high for such tetrahedral amorphous carbon (ta-C) coatings, which is a good prerequisite for industrial applications. The ta-C layers with very high hardness and smooth surface are well suited as wear resistant layers.

Study of the Nonlinear Optical Properties of Ag/CdTe Composites

CdTe films, Ag nanoparticles, and Ag/CdTe composites are successfully fabricated on substrates by means of the physical vapor deposition process. The morphological structure, crystal growth and bandgap of the samples are specifically characterized by scanning electron microscopy, X‐ray diffractometer, and UV–vis spectrophotometer. Picosecond (ps) Z‐scan technology is used to investigate the nonlinear optical (NLO) properties of the composites under 532 nm. The results indicate that all samples exhibit saturated absorption nonlinear absorption properties and self‐dispersion nonlinear refraction properties. In addition, Ag nanoparticles can improve the NLO properties of Ag/CdTe composites, and this improvement is more obvious with the increase of Ag power. The results show that the excellent properties of the Ag/CdTe composites are expected to make them an ideal material for use in the photoelectric field.

EMI Shielding for System in Package Using Spray Coating and Silver Particle-Free Ink

There is a constant drive to pack electronics into smaller spaces. Recently, IoT devices such as smart watches, wearables and other connectivity devices have been major drivers of further miniaturization and spurred System in Package ‘SIP’ innovations. SIP enables several integrated circuits (ICs) along with larger capacitors/inductors to be housed in one package. Many of these ICs operate at radio frequencies and the proximity increases electromagnetic interference (EMI). The traditional solution of soldering a ‘metal can’ is not feasible. On the other hand, 5G enabled devices and high frequency communication electronics require shielding well beyond RF, typically 5 ? 25 GHz and beyond. Compartmental and conformal shielding of the package is necessary and sputtered metal has typically been utilized to provide the shield. The traditional sputtering method is a Physical Vapor Deposition process (PVD) that involves vaporizing a metal and depositing it onto the surfaces of the components. PVD is currently the most commonly used method to apply the EMI shield and it requires a complex, multi-step process. Alternatively, the technology is seeing a shift to sprayable or jettable conductive-based ink conformal shielding. This approach brings about substantial total cost of ownership and UPH/throughput advantages as the ink-based processes (spray/jet) does not require vacuum, and relatively low temperatures (at or below 180C in most cases). From a technology perspective, ink-based approaches have the advantage in shielding complex 3D, non line-of-sight packages and electronic module housings, directed (mask-less) shielding with no major drop in shielding performance or REL (reliability) behavior.

Effect of a Novel sputtering process on the chemical and biological properties of silver-gold alloys.

Silver-gold nanocrystalline films were sputtered on HDPE substrates by a physical vapour deposition process using alloys with a nominal composition of 65% silver/35% gold or 35% silver/65% gold by weight, with comparison to a 100% silver target. Novel process conditions were introduced to include both water and oxygen as reactive gases. X-ray diffraction and chemical digests were used to assess the structure and chemical composition of the films. Log reductions and corrected zone of inhibition tests were used to measure the biological properties. Despite a range of physical and chemical properties, biological tests showed that the bactericidal properties of all silver-gold films were comparable with silver-only films in the short term and 65% silver films made with Novel sputtering conditions had comparable bacteriostatic abilities to silver-only over a 7-day period. The benefit of including gold may be seen in future studies of anti-inflammatory activity.

Improvising CODAS method functionalized with grey numbers to improve the performance of PVD titanium carbon nitride (TiCN) thin film coating: a novel approach

This experimental study focuses on the deposition of TiCN thin film coating onto a bare p-type silicon substrate using physical vapor deposition (PVD) processes, with varying process parameters. The study employed a design of experiment in accordance with the L 16 orthogonal Array, followed by the implementation of the combinative distance-based assessment (CODAS) method functionalized with grey numbers to enhance the performance of the PVD process for the very first time in the film of thin film deposition. The study also conducted various analyses to examine the coating’s properties, including morphological, structural, microstructural, electrochemical, and mechanical properties. According to the result, the morphology of the coating was wavy in nature, with a smooth microstructure and a few agglomerated particles. The structure of the film indicated that TiCN had a single-phase FCC structure, while the mechanical and electrochemical properties improved with higher N2 flow rates. Additionally, the analysis by CODAS method functionalized with grey numbers suggested that substrate to target distance = 50 mm, N2 flow rate = 25 sccm, and bias voltage = −120 V were the most suitable condition for obtaining the best quality of TiCN thin film coating.

Optimization of physical vapor deposition process for low background nanoimprinted SERS substrate in quantitative melamine analysis

Uniformity, sensitivity, reproducibility, and cost are the critical parameters of practical surface-enhanced-Raman-spectroscopy (SERS) substrates. Herein, we proposed a High-Aspect-Ratio-Nano-Pillar-Array (HARNPA) substrate deposited silver by physical vapor deposition (PVD) methods (e.g. E-beam evaporation, sputtering, and a two-stage intermittent sputtering) to fabricate high-performance SERS substrates. The substrate by the E-beam evaporation has a significant SERS effect, but the Raman background induced by the exposure of the polymer HARNPA limits the analyte choice. The substrate by the sputtering method has better step coverage of silver but a lower enhancement factor. Therefore, we proposed a process of two-stage intermittent sputtering to solve these limitations. In addition, we define a factor called the signal-to-background peak ratio (S/B peak ratio) to evaluate the influence of the Raman background from the SERS substrate. Finally, we accomplished a SERS substrate with an S/B peak ratio of 3.48 by intermittent sputtering, which has the best linearity (R2 = 0.97) of the melamine concentration curve and the lowest detection limit (LoD = 5.6 × 10-7 M) that meets the regulatory requirements for melamine detection (3.96 × 10-6 M). The benefits of our SERS substrates are easy fabrication, high sensitivity (EF = 1.44 × 107), high reproducibility (CV = 8.4 %), and excellent uniformity (CV = 7 % in 4″ area), which are beneficial for mass production in the future.

Self‐Limited Epitaxial Growth of Patterned Monolayer Organic Crystals for Polarization‐Sensitive Phototransistor with Ultrahigh Dichroic Ratio

AbstractMonolayer organic crystals provide an unprecedented opportunity for studies on the intrinsic charge transport of organic semiconductors because of their 2D nature that is free of grain boundaries with fewer defects. However, due to the spatially stochastic molecular nucleation and the difficulty in controlling monolayer assembly, large‐scale growth of monolayer organic crystals remains a formidable challenge. Here, a self‐limited epitaxial growth strategy is proposed to realize large‐area patterned growth of monolayer organic crystals via physical vapor deposition process. Specifically, this approach confines the molecular nucleation and crystallization in defined wetting patterns, whose sizes are smaller than the mean free path of the molecules on substrate, enabling the formation of a single nucleus in wetting pattern. Meanwhile, the intermolecular lattice mismatch between 2,7‐dialkyl[1]benzothieno[3,2‐b][1]benzothiophene (Cn‐BTBT, n = 8 and 10) derivatives inhibits vertical molecular stacking, thereby promoting the monolayer assembly of organic molecules. Using this approach, centimeter‐sized patterned growth of mixed Cn‐BTBT monolayer organic crystals is achieved. Polarization‐sensitive phototransistors based on the monolayer organic crystals exhibit ultrahigh dichroic ratio up to 4.6 × 103, on par with the commercial polarizers (103). This work sheds light on large‐scale patterned growth of monolayer organic crystals toward high‐performance optoelectronic devices.

Spectrum‐Selective High‐Temperature Tolerant Thermal Emitter by Dual‐Coherence Enhanced Absorption for Solar Thermophotovoltaics

AbstractSolar thermophotovoltaics (STPV) receive considerable attention for the record high energy transfer efficiency beyond conventional photovoltaics systems, which requires a well‐designed structured absorber/emitter and high operating temperature. However, the inherent tradeoff between increased operation temperature and material/structure stability (especially for the thermal emitters) severely hinders the development of STPV. In this work, a new design is proposed for a step‐function‐like thermal emitter based on a two‐path (quasi) coherent perfect absorption effect, which is experimentally enabled by a few‐layer Si/Mo/AlN lamellar film on a Mo substrate through a sequential physical vapor deposition process. The as‐prepared lamellar emitter exhibits maximal emissivity of ≈97% for 1.4 µm with excellent thermal suppression down to 10% across 3.4–10 µm, the performance of which is well maintained up to 973 K. When employed in the established STPV system, the dual coherent enhanced absorption (DCEA) system contributes to an increase of 20% in the total system efficiency compared to the unimodal coherent perfect absorption counterpart. The design proposed in this study provides a new methodology for improving the efficiency of the STPV system and may have significant applications in improving thermal energy regulation for compact systems.