Search Results (380)

The ecological-driven sustainability of plastic materials encounters a major challenge in eco-efficient mechanical recycling falling short of meeting the required quality and quantities of post-consumer recyclates (PCRs) in sensitive application areas demanded by regulatory authorities. Those toxicological residues of contaminants that remain after mechanical recycling restrict PCRs use in sensitive application areas. Addressing the integration of PCR into high-demand applications such as food contact materials, this work investigates a novel technology for PCR product use by an innovative migration barrier development pathway of Si-based plasma-enhanced chemical vapor deposition (PECVD) coatings on pre-contaminated polypropylene (PP) model PCR cups, developed with consideration of applicable regulatory frameworks, including European Food Safety Authority (EFSA) requirements for food contact materials. As a starting point for migration barrier development, suitable oxygen transmission rate (OTR) barrier coatings for PCR cups were reproduced and transferred on virgin and model PCR PP cups. The coating procedure consisted of a pretreatment, an applied organic adhesion interlayer SiOCH and an inorganic functional barrier layer SiO_x, where the functionality was related to the applied SiO_x layer based on the barrier efficiency. Therefore, SiO_x was varied in the migration barrier development to find a suitable process window and efficiently correlate the effects of process parameters on OTR before and after migration testing, mass loss of simulant and the reduction in migration of eight introduced contaminants in the model PCR cup using GC/MS. This work advanced the understanding of PECVD for migration barriers under regulatory frameworks and reduced PCR matrix complexity in the analysis during development using model PCR cups. Full article

This study focuses on the impact of plasma-enhanced chemical vapor deposition (PECVD) synthesis parameters on the characteristics of a synthesized vertical array of multi-walled carbon nanotubes (VMWCNT). Catalytic synthesis is carried out on a thin nickel film on a silicon substrate after breakup of the Ni film into nanoparticles during pretreatments–oxidation and reduction. The influence of growth temperature, synthesis duration, plasma parameters, working pressure, and precursor concentration on the morphology and geometry of VMWCNT is investigated. A detailed combination of scanning electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) is used to analyze the evolution of geometry, defect density, and nitrogen doping of carbon nanotubes (CNT) with varying synthesis temperatures. The work includes recommendations for adapting PECVD synthesis to achieve predictable and reproducible growth of VMWCNT with optimal properties for specific technological applications. Full article

Background: The optical losses in the form of reflections, parasitic absorption, and scattering limit photovoltaic efficiency. This review examines plasma-assisted surface engineering as an effective tool for improving light management in solar cells. Plasma-based methods, including etching, oxidation, deposition, and texturing, enable precise control of surface morphology and chemistry, lowering reflectance, enhancing light trapping, and passivating defects. Methods: In contrast to wet-chemical or high-temperature processes, plasma processes are dry, low-temperature, scalable, and can be used with silicon, perovskite, thin-film, and organic solar cells, as well as tandem structures. The fundamentals of optical losses are described, along with the principles of radio-frequency (RF), inductively coupled plasma (ICP), microwave, and atmospheric plasma systems and their distinctive advantages for controlling ion and reactive-species generation. Key applications reviewed include black-silicon texturing by ICP reactive-ion etching (ICP-RIE), anti-reflective/passivation coatings by plasma-enhanced chemical vapor deposition (PECVD), and interface activation by atmospheric plasma. Results: Among performance improvements are a reflectance of less than 2%, a photocurrent increase of 10–20%, and longer carrier lifetime. Conclusions: The advantages of plasma compared to lithography and sol–gel processes are in the precision and affordability of the method. The difficulties include damage caused by the processing, uniformity over extensive areas, and environmental stress resistance. Future directions rely on low-temperature plasmas for flexible PV, machine-learning-guided process optimization, and hybrid plasma–laser systems. This synthesis of otherwise fragmented studies is intended to support the implementation of plasma-based methods in next-generation, high-efficiency, and sustainable solar production. Full article

Harsh-environment pressure sensing requires piezoelectric materials that can simultaneously withstand elevated temperature, mechanical loading, and structural degradation. GaN is a promising lead-free piezoelectric semiconductor owing to its wide bandgap, high thermal stability, and non-centrosymmetric wurtzite structure. However, its piezoelectric output can be significantly affected by free-carrier compensation in unintentionally n-type GaN. Here, we report a flexible all-inorganic piezoelectric pressure sensor based on a directly grown h-BN/GaN heterostructure thin film. The h-BN layer was deposited on GaN/Si by plasma-enhanced chemical vapor deposition, followed by backside Si removal, electrode deposition, and transfer onto a flexible Cu foil substrate. Structural characterizations confirmed the formation of a compact h-BN/GaN interface with clear lattice fringes, preferential out-of-plane orientation, and characteristic Raman signatures of both h-BN and GaN. Compared with the flexible GaN/Cu reference, the h-BN/GaN device exhibits modified interfacial electrical transport behavior, enhanced voltage and current-density outputs, and prolonged transient voltage retention. Finite-element simulations reveal modified electrostatic potential distribution after h-BN integration, while electrical and interfacial characterizations suggest electronic structure modulation and reduced carrier compensation effects at the heterointerface. Raman optothermal analysis indicates an improved relative/local thermal response of the h-BN/GaN device under identical optical excitation conditions, supporting its enhanced thermal robustness. Under 200 psi at 400 °C, the h-BN/GaN sensor maintains an output voltage of approximately 27.65 mV, about 2.32 times that of the GaN reference. This work demonstrates an interfacial engineering strategy based on two-dimensional h-BN integration for constructing flexible, thermally robust, and high-output piezoelectric sensors for harsh-environment monitoring. Full article

In this work, boron incorporation in diamond grown by microwave plasma-enhanced chemical vapor deposition is investigated as a function of methane concentration, boron precursor concentration, crystalline orientation, oxygen addition to the plasma, and deposition temperature. The boron incorporation efficiency, i.e., the ratio between the boron concentration in diamond and the gas-phase boron-to-carbon ratio, spans several orders of magnitude and can exceed unity for all investigated crystalline orientations. Overall results demonstrate that methane concentration and the substrate’s crystalline orientation are key factors governing boron incorporation. The temperature study reveals that boron incorporation is also governed by thermally activated boron-loss mechanisms. Finally, all results show that boron incorporation is not exclusively controlled by the plasma composition but also by surface growth mechanisms. Full article

Glass fiber-reinforced plastics (GFRPs) rely on strong fiber–matrix adhesion to achieve optimal mechanical performance. However, conventional sizing systems provide only partial surface coverage and may limit interfacial bonding. The current study investigates atmospheric-pressure plasma-enhanced chemical vapor deposition (APECVD) as an alternative approach for depositing adhesion-promoting plasma coatings on glass fibers intended for epoxy-based composites. Organosilane precursors were deposited using an atmospheric plasma jet under different operating conditions, and the chemical composition and the morphology of the resulting plasma coatings were extensively characterized. Adhesion performance was evaluated by pull-off tests on glass sheets and pull-out tests on glass fibers embedded in epoxy resin. Results show that the plasma coatings provide complete surface coverage and present a tunable chemistry containing several adhesion-promoting functional groups, including silanol and amine-containing species. Pull-off tests on glass sheets demonstrate adhesion improvements of at least 68% compared with untreated glass. In pull-out tests, plasma-coated glass fibers achieved interfacial shear strengths up to 102.9% higher than untreated fibers and 24.4% higher than an industrial reference material. These results demonstrate how atmospheric plasma polymerization can produce effective adhesion-promoting coatings on glass surfaces, thus offering a promising and industrially scalable alternative to conventional adhesion promoters for epoxy-based GFRPs. Full article

In this paper, a 2.5 nm thick Al₂O₃ interlayer deposited by atomic layer deposition was inserted between AlGaN/GaN HEMT structure and SiN_x passivation layer to reduce interface damage of the semiconductor/dielectric introduced directly by plasma-enhanced chemical vapor deposition. It is found that this ultra-thin Al₂O₃ interlayer can not only obviously increase the output current and extrinsic transconductance by reducing the access-region resistance, but also effectively suppress current collapse and the threshold voltage drift due to fewer interface defects in the access region between the gate and drain. More importantly, dynamic on-resistance degradation of devices with an Al₂O₃ interlayer is significantly improved in comparison with the only Si₃N₄-passivated HEMTs without an Al₂O₃ interlayer. Full article

High-output-current boron-doped diamond (B-diamond) metal–oxide–semiconductor field-effect transistors (MOSFETs) with a modulated boron-doped epitaxial layer were fabricated. An intrinsic diamond epitaxial layer was deposited on the single-crystal diamond substrate as a buffer layer, and plasma-enhanced chemical vapor deposition (PECVD) SiO₂ was employed as both the gate dielectric and passivation layer. The boron-doped epitaxial layer has a thickness of approximately 500 nm and a boron concentration in the range of 10¹⁷–10¹⁸ cm⁻³. The B-diamond MOSFETs showed clear p-channel operation, with a maximum output current of −0.18 mA/mm at room temperature. When the temperature was increased to 150 °C, the maximum output current increased to −1.05 mA/mm, while the on-resistance decreased from 413.91 to 12.13 kΩ·mm. The on/off ratio remains approximately 10⁵ over the measured temperature range. In addition, the device exhibited a breakdown voltage of −347 V at a gate-to-drain spacing of 12.5 μm, and the simulation results showed that the peak electric field was mainly concentrated near the drain-side gate edge of the passivation layer. These results indicated that, for the B-diamond MOSFETs, a balanced epitaxial layer thickness and boron concentration were essential for achieving sufficient channel conduction as well as effective gate control ability. Full article

The interaction of biomaterial surface with cells is a pivotal factor in tissue engineering and three-dimensional (3D) modeling. This paper presents an approach to modifying polystyrene surface by plasma-enhanced chemical vapor deposition of thin plasma-polymerized hexamethyldisiloxane (pp-HMDSO) films to enhance biocompatibility and stimulate the formation of 3D cellular structures. The coatings were characterized by SEM, EDS, XPS, FTIR, AFM, contact angle measurements, and surface free energy (SFE) analysis. A hydrophobic surface initiates 3D structure formation by ensuring uniform cell repulsion and stimulating intercellular interactions. Biological evaluation was performed on U-87 MG (glioblastoma) and HMC3 (microglia) cell lines. For U-87 MG, the pp-HMDSO layer proved critical: cell death and atypical adhesion occurred on untreated plastic, whereas stable spheroids formed on the modified surface. HMC3 cells formed small spheroids even on unmodified surfaces, but on pp-HMDSO coatings, the process was more intense and the structures more uniform due to surface hydrophobicity. These results demonstrate the potential of plasma-polymerized HMDSO films as a scalable platform for creating biomaterials with controlled properties for 3D culturing. Full article

Among numerous atmospheric-pressure plasma jets (APPJs), high industrial acceptability has been reached for the ones based on high-voltage, low-current, vortex-stabilized arc, typically operated with kHz DC-pulses. This review explores the interrelations between the “process” in a chemical–physical sense and “process”, or to better differentiate, “processing” in the sense of technological treatment, with respect to such APPJs. The mutual dependence of the processing requirements (e.g., high processing speed, compatibility with robotic processing, low total cost of ownership, reliability, and long service intervals) and the physical and chemical processes in the plasma jet are analyzed. The focus is on the hybrid character of the produced plasma, comprising a non-equilibrium arc and a diffuse plasma. Different operation modes of the gliding arc discharge (GAD) are discussed. The reviewed chemical processes are the generation of reactive oxygen–nitrogen species (RONS), oxidation and reduction reactions, and interactions with vapors, solids, and liquids. The considered processing examples are established applications, such as surface activation, cleaning, oxide reduction, film removal, and coating, as well as emerging applications for sterilization and plasma-activated water (PAW) production. Full article

Graphene was directly synthesized on monocrystalline Si(100) at 500 °C by microwave plasma-enhanced chemical vapor deposition using an increased CH₄/H₂ gas flow ratio. Raman analysis revealed spectral features and intensity ratios consistent with the growth of hydrogenated graphene and revealed changes in defect structure, graphene layer number, and self-doping. Atomic force microscopy measurements showed that the surface morphology and local conductivity strongly depended on the growth conditions. The electrical and photoelectrical characteristics of graphene/Si junctions were correlated with the Raman parameters and surface morphology. For the hydrogenated graphene samples synthesized at 500 °C, the photocurrent, short-circuit current, and open-circuit voltage were found to be competitive with those of pristine graphene reference samples grown at 700 °C. The results demonstrate the potential of low-temperature direct PECVD synthesis for graphene/Si optoelectronic devices. Full article

With the shift in advanced packaging toward 3D integration and flexible electronics, it is becoming critical to produce high-quality silicon nitride films under low thermal budgets. To overcome the limitations of low-temperature deposition, this study compares two gas mixtures—SiH₄/NH₃/N₂ and SiH₄/N₂—in plasma-enhanced chemical vapor deposition of silicon nitride coatings. We systematically evaluated how the NH₃ precursor affects deposition kinetics, chemical bonds, non-uniformity, optical properties, and internal stress at different RF powers and electrode gaps. The test results show that NH₃, with its lower dissociation energy, avoids the high activation barrier associated with pure N₂ plasma, leading to a higher reactive nitrogen flux and a doubled deposition rate. In the SiH₄/NH₃/N₂ system, raising RF power from 300 W to 900 W reduced hydrogen content from 23.58% to 12.25%. This suppression of hydrogen promoted structural densification, shifting the mechanical stress from 173.3 MPa to −989.7 MPa. At a larger electrode gap of 19 mm, NH₃’s better diffusion characteristics offset the electric field sensitivity typical of N₂ systems, reducing large-area film non-uniformity by 28.7% compared to a 13 mm gap. This work offers a practical, mass-production-friendly approach for depositing robust, low-hydrogen, highly uniform silicon nitride films at low temperatures. Full article

Surface engineering strongly influences the performance, reliability, and safety of medical and biomedical devices, yet failures often originate at interfaces rather than in bulk materials alone. This review addresses the fragmented evidence base linking coating selection, interphase design, qualification testing, advanced characterization, and data-driven durability analysis. The objective is to provide an integrative, failure-mode-based framework for implants, reusable instruments, inhalation systems, diagnostics, wearables, and implantable electronics. A narrative synthesis of the peer-reviewed literature in coatings, biomaterials, electrochemistry, reliability, standards, and materials informatics was conducted, with qualitative tables used only when protocols were too heterogeneous for numerical pooling. The review compares physical vapor deposition (PVD), chemical and plasma-enhanced chemical vapor deposition (CVD/PECVD), atomic layer deposition (ALD), sol–gel/organically modified silica (ORMOSIL) hybrids, plasma polymers, parylene, bioactive or antimicrobial surfaces, and electronic encapsulation strategies. The main finding is that no universally superior coating exists; reliable performance depends on matching architecture and characterization to the dominant failure pathway, substrate compliance, geometry, sterilization or physiologic exposure, and the standards-constrained endpoint. The review further shows how electrochemical diagnostics, interfacial mechanics, multiphysics models, survival/reliability statistics, and carefully governed AI workflows can be combined to support service-life prediction and decision-oriented qualification. Full article

A two-step growth process was developed to fabricate a 3-inch homogeneously {100}-textured free-standing diamond wafer by microwave plasma enhanced chemical vapor deposition (MPCVD). The sequential growth process is based on a change in the growth parameter α, which is given by the growth rates on {100} and {111} facets, α = $\sqrt{3}$·(V₁₀₀/V₁₁₁). Initial growth was executed with nitrogen addition, yielding an α value close to 3 for evolutionary selection of the (100) face, followed by cessation of nitrogen addition to yield a lower α value. A homogeneously grown {100}-textured diamond over an area of ca. 175 cm² with a thickness ≥ 0.8 mm was obtained after 196 h growth. The diamond growth rate was 4.0–5.5 µm/h, which is four times higher than the conventional growth of oriented diamond. This was substantiated by optical microscopy, Raman spectroscopy, and XRD analysis. The large crystal size of 210 ± 60 µm has been assigned to the second growth step, where growth is preferentially in the <111> direction. The homogeneous {100} texture and the large crystal size are conducive to achieving high thermal conductivity, as the in-plane thermal conductivity of the polycrystalline diamond wafer was increased from ca. 850 W/(mK) to 1125 W/(mK). Full article

Optical fiber sensors deployed in harsh industrial fields, e.g., high-temperature wet-oxygen, face severe challenges in signal attenuation and mechanical degradation. While amorphous silicon oxycarbide (a-SiOC) coatings offer a promising solution due to their adjustable thermo-mechanical properties, balancing their structural density with environmental stability remains a critical technical bottleneck. In this study, a-SiOC coatings were deposited on optical fibers using hexamethyldisilane (HMDS) and trace oxygen via radio-frequency capacitively coupled plasma-enhanced chemical vapor deposition (PECVD). A systematic investigation was conducted to determine the impact of deposition temperature (70–420 °C) on the precursor dissociation kinetics, microstructural evolution, and corrosion resistance of the coatings. An elevation in temperature promotes the elimination of organic terminal groups (–CH₃, –H) and enhances surface diffusion, driving the coating from a loose, carbon-rich “polymer-like” structure (dominated by Si–C bonds) to a dense, inorganic “silica-like” skeleton (dominated by Si–O–Si bonds). High-temperature corrosion tests in a wet-oxygen environment (500–900 °C) demonstrate that the failure mechanism is highly dependent on deposition temperature. Coatings deposited at low temperatures suffer catastrophic cracking due to pronounced oxidative shrinkage and the release of volatile species, whereas coatings deposited at 420 °C exhibit microcracking caused by severe carbon phase separation and stress concentration within the rigid inorganic network. In the present system, 350 °C is identified as the optimal deposition temperature, as it achieves the best balance of network densification and structural flexibility, while exhibiting the best mechanical performance. Full article