Search Results (46)

Pulsed laser annealing (PLA) was performed on a 0.3 μm thick hydrogenated amorphous carbon (a-C:H) film deposited on silicon substrate by plasma-enhanced chemical vapor deposition (PECVD). The 532 nm, 32 ns PLA ranged in fluence from 0.2 to 0.94 J cm⁻². There were no visible signs of film delamination over the entire fluence range for a single pulse. As the fluence increased, graphitization of the amorphous film bulk was observed. However, at the near surface of the film, there was a concomitant increase in sp³ content. The sp³ bonding observed is the result of the formation of a thin diamond-like layer on the surface of the carbon film. Along with increasing laser fluence, the film swelled by 75% up to 0.6 J cm⁻². In addition, carbon fiber formation was observed at 0.6 J cm⁻², increasing in size and depth up through 0.94 J cm⁻². The origin of this transformation may be associated with a rapid outgassing of hydrogen from the amorphous carbon during the PLA step. Additionally, there was a dramatic increase in the visible light absorption of these thin films with increasing laser fluence, despite the films being less than a micron thick. These results suggest that PLA of a-C:H film is a useful method for modifying the surface structure for optical or electrochemical applications without film ablation. Full article

Hydrogenated amorphous carbon (a-C:H) films are widely valued for their excellent mechanical strength and low friction, but their performance significantly degrades at elevated temperatures, limiting practical applications in aerospace environments. In this work, we aimed to enhance the high-temperature tribological behavior of a-C:H films through controlled silicon (Si) doping. A series of a-C:H:Si films with varying Si contents were fabricated via direct current magnetron sputtering, and their microstructure, mechanical properties, and friction behavior were systematically evaluated from room temperature up to 400 °C. Results show that moderate Si doping (8.3 at.%) substantially enhances hardness and wear resistance, while enabling ultralow friction (as low as 0.0034) at 400 °C. This superior performance is attributed to the synergistic effects of transfer layer formation, preferential Si oxidation, and tribo-induced graphitization. This study provides new insights into the high-temperature lubrication mechanisms of Si-doped a-C:H films and demonstrates the critical role of Si content optimization, highlighting a viable strategy for extending the thermal stability and lifespan of solid-lubricating films. Full article

Copper-doped hydrogenated amorphous carbon (Cu-doped a-C:H) films were synthesized using copper as the cathode and C₂H₂ as the precursor. The result shows that the negative bias voltage can affect the composition and microstructure of nanocomposite films. With bias voltage increasing, Cu content first increases in the range of 50~300 V and then declines with higher voltage, while the deposition rate decreases continuously. The stress and sp³ content present a similar trend with the bias voltage, increasing during the range from 50 V to 200 V and then decreasing with higher voltage. Full article

In the present study, for the first time, aluminum-doped zinc oxide (AZO) thin films with nanoinclusions of amorphous carbon have been synthesized via spin coating, and the thermoelectric performances were investigated varying the aging period of the solution, the procedure of carbon nanoparticles’ addition, and the annealing atmosphere. The addition of nanoparticles has been pursued to introduce phonon scattering centers to reduce thermal conductivity. All the samples showed a strong orientation along the [002] crystallographic direction, even though the substrate is amorphous silica, with an intensity of the diffraction peaks reaching its maximum in samples annealed in the presence of hydrogen, and generally decreasing by the addition of carbon nanoparticles. Absolute values of the Seebeck coefficient improve when nanoparticles are added. At the same time, electric conductivity is higher for the sample with 1 wt.% of carbon and annealed in Ar with 1% of H₂, both increasing in absolute value with the temperature rise. Among all the samples, the lowest thermal conductivity value of 1.25 W/(m∙K) was found at room temperature, and the highest power factor was 111 μW/(m∙K²) at 325 °C. Thus, the introduction of carbon effectively reduced thermal conductivity, while also increasing the power factor, giving promising results for the further development of AZO-based materials for thermoelectric applications. Full article

This study explores the low-temperature synthesis of graphene using plasma-enhanced chemical vapor deposition (PECVD), emphasizing the optimization of process parameters to achieve controlled growth of pristine and hydrogenated graphene. Graphene films were synthesized at temperatures ranging from 700 °C to as low as 400 °C by varying methane (25–100 sccm) and hydrogen (25–100 sccm) gas flow rates under 10–20 mBar pressures. Raman spectroscopy revealed structural transitions: pristine graphene grown at 700 °C exhibited strong 2D peaks with an I(2D)/I(G) ratio > 2, while hydrogenated graphene synthesized at 500 °C showed increased defect density with an I(D)/I(G) ratio of ~1.5 and reduced I(2D)/I(G) (~0.8). At 400 °C, the material transitioned to a highly hydrogenated amorphous carbon film, confirmed by photoluminescence (PL) in the Raman spectra. Atomic force microscopy (AFM) showed pristine graphene with a root mean square roughness (R_q) of 0.37 nm. By carefully adjusting PECVD synthesis parameters, it was possible to tune the surface roughness of hydrogenated graphene to levels close to that of pristine graphene or to achieve even smoother surfaces. Conductive AFM measurements revealed that hydrogenation could enhance graphene’s contact current under specific conditions. The findings highlight the role of PECVD parameters in tailoring graphene’s structural, morphological, and electronic properties for diverse applications. This work demonstrates a scalable, low-temperature approach to graphene synthesis, offering the potential for energy storage, sensing, and electronic devices requiring customized material properties. Full article

In this research, two intermediate layers were deposited on 316L stainless steel to improve the adhesion of diamond-like carbon (DLC) films, one composed of Ti_xAl and produced using the RF sputtering technique with three thicknesses, 100 nm, 200 nm, and 300 nm; the other, interlayer composed of amorphous hydrogenated silicon (a-Si:H). The DLC films were deposited using the pulsed-DC PECVD method with an active screen to achieve the AISI 316L/Ti_xAl//DLC and AISI 316L/TiₓAl/a-Si/DLC configurations. The binding energy between the substrate/Ti_xAl and Ti_xAl/a-Si:H was investigated via X-ray photoelectron spectroscopy with high-resolution spectra. The chemical composition and microstructure of the titanium–aluminum interlayers were investigated using energy-dispersive X-ray spectroscopy and X-ray diffraction, and the microstructure of the DLC coatings was studied using Raman spectroscopy. The coatings’ adherence was measured using scratch and indentation tests, and the hardness of the DLC coatings was determined with the nanoindentation test. The X-ray diffractograms did not allow the determination of any crystalline structure in the Ti_xAl interlayers. The XPS results showed that between the AISI 316L substrate and the Ti_xAl intermediate layer, Ti-O-Fe and FeAl₂O₄ were formed. On the other hand, at the Ti_xAl/a-Si:H interface, TiSi₂ and Al₂SiO₅ compounds were identified. The DLC coatings grew as hydrogenated amorphous carbon with a hydrogen content of around 30 at.% and a hardness of 24 GPa. The deposition methods used and the Ti_xAl/a-Si:H interlayers allowed the obtainment of adherent DLC coatings on AISI 316L stainless steel substrates. High critical load values of about 30 N were obtained. The novelty of this work is underscored by the absence of previous studies that thoroughly examine the bonds present in interlayers used as gradients to enhance the adhesion of DLC. Full article

Amorphous carbon is recognized as an excellent lubricating material; however, its tribological properties are significantly influenced by humidity. To elucidate the mechanism underlying this humidity dependence and to propose a novel enhancement method, we investigated and compared the tribological properties of hydrogenated amorphous carbon (a-C:H) and amorphous carbon/gold (a-C/Au) composite films. First, the friction coefficient of these carbon films under different humidity conditions was tested using a rotational ball-on-disk tribometer. Subsequently, we analyzed the morphology and structure of the sliding interface employing optical microscopy (OM), Raman spectroscopy, transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM). Finally, first-principle calculations were carried out to calculate the adsorption energy of water molecules on different surfaces. The results indicate that the friction coefficient of a-C:H film and the area of transfer film increase with the increase of humidity. This phenomenon can be attributed to the fact that water molecules enhance the interaction between the a-C:H film and steel counterfaces. Notably, in contrast, the friction coefficient of a-C/Au film demonstrates low sensitivity to humidity due to the formation of an Au transfer film that exhibits weak interaction with water molecules. These findings provide a promising strategy for developing environment-adaptive amorphous carbon films and play an important role in promoting the development of intelligent lubricating film. Full article

Sulfuric acid is a concern for contacts within electronic devices, and the application of amorphous carbon films as thin electrical insulating coatings for small coils requires full investigation of its effects. Five types of amorphous carbon films were fabricated on Si substrates under different deposition conditions using vacuum coating systems. Based on their optical constants (ISO 23216:2021(E)), the films were classified into three types: hydrogenated amorphous carbon (a-C:H), polymer-like carbon (PLC), and graphite-like carbon (GLC). The structure, surface composition, and electrical insulation properties of the films were evaluated before and after immersion in sulfuric acid. Although the PLC and a-C:H showed progression of surface oxidation due to sulfuric acid immersion, none showed obvious changes in their structure or DC dielectric breakdown field strength due to sulfuric acid immersion, proving their stability. Furthermore, the PLC and a-C:H, which had a relatively low extinction coefficient, exhibited excellent insulation properties. Our results suggest that amorphous carbon films can be useful as thin insulating films for small coils that may come in contact with sulfuric acid. Our study offers a valuable tool for general users in the industry to facilitate selection of electrical insulating amorphous carbon films based on optical constants, such as extinction coefficients. Full article

Tetrahedral amorphous carbon (taC) is a hydrogen-free carbon with extensive properties such as hardness, optical transparency, and chemical inertness. taC coatings have attracted much attention in recent times, as have coatings doped with a noble metal. A known antimicrobial metal agent, silver (Ag), has been used as a dopant in taC, with different Ag concentrations on the Ti64 coupons using a hybrid filtered cathodic vacuum arc (FCVA) and magnetron sputtering system. The physiochemical properties of the coated surface were investigated using spectroscopic and electron microscopy techniques. A doping effect of Ag-taC on biofilm formation was investigated and found to have a significant effect on the bacterial-biofilm-forming bacteria Staphylococcus aureus and Pseudomonas aeruginosa depending on the concentration of Ag. Further, the effect of coated and uncoated Ag-taC films on a pathogenic bacterium was examined using SEM. The result revealed that the Ag-taC coatings inhibited the biofilm formation of S. aureus. Therefore, this study demonstrated the possible use of Ag-taC coatings against biofilm-related complications on medical devices and infections from pathogenic bacteria. Full article

Silver-based antibacterial coatings limit the spread of hospital-acquired infections. Indeed, the use of silver and silver oxide nanoparticles (Ag and AgO NPs) incorporated in amorphous hydrogenated carbon (a-C:H) as a matrix demonstrates a promising approach to reduce microbial contamination on environmental surfaces. However, its success as an antibacterial coating hinges on the control of Ag⁺ release. In this sense, if a continuous release is required, an additional barrier is needed to extend the release time of Ag⁺. Thus, this research investigated the use of a plasma fluoropolymer (CF_x) as an additional top layer to elongate Ag⁺ release and increase the antibacterial activity due to its high hydrophobic nature. Herein, a porous CF_x film was deposited on a-C:H containing Ag and AgO NPs using pulsed afterglow low pressure plasma polymerization. The chemical composition, surface wettability and morphology, release profile, and antibacterial activity were analyzed. Overall, the combination of a-C:H:Ag (12.1 at. % of Ag) and CF_x film (120.0°, F/C = 0.8) successfully inactivated 88% of E. coli and delayed biofilm formation after 12 h. Thus, using a hybrid approach composed of Ag NPs and a hydrophobic polymeric layer, it was possible to increase the overall antibacterial activity of the coating. Full article

We report on investigating the structural and electronic properties of semiconducting and insulating layers produced in a process resembling percolation in a unique cold plasma fabrication method (plasma-enhanced chemical vapor deposition—PECVD). Amorphous carbon–tin films (Sn–C) produced from tetramethyl tin (TMT) with an acoustic-frequency glow discharge in a three-electrode reactor were investigated. The layers, after air exposure, oxidized to SnO₂/Sn–C. Depending on the coupling capacitance applied to the plasma reactor, the films could be obtained in the form of an amorphous semiconductor or an amorphous insulator. We assume that the semiconductor consists of an internal network of channels auto-organized during deposition. The insulator does not demonstrate any internal structure features. An investigation on conductive filaments creating low-dimensional (LD) nanojunctions in the semiconductor and the location of energetic levels in the insulator was performed. The main parameters of the electronic band structure of the insulating film, such as the transport gap E_G (5.2 eV), optical gap E_opt (3.1 eV), electron affinity Χ (2.1 eV), and ionization potential J (7.3 eV), were determined. We have demonstrated a simple approach for developing a catalyst candidate consisting of amorphous semiconductor–insulator nanojunctions for (photo)catalytic hydrogen evolution or CO₂ reduction. Full article

We develop a method for the laser synthesis and deposition of carbon–gold films formed by a net of linear sp-carbon chains and stabilized by gold nanoparticles. The originality of the method is in the simultaneous production of carbon chains and gold nanoparticles due to the laser fragmentation of the amorphous carbon and hydrogen tetrachloroaurate (III) or chloroauric acid. We study how surface resistivity alters the effect of the obtained films via the illumination in the visible spectral range. Full article

Over the last few years, there has been increasing interest in the use of amorphous carbon thin films with low secondary electron yield (SEY) to mitigate electron multipacting in particle accelerators and RF devices. Previous works found that the SEY increases with the amount of incorporated hydrogen and correlates with the Tauc gap. In this work, we analyse films produced by magnetron sputtering with different contents of hydrogen and deuterium incorporated via the target poisoning and sputtering of C_xD_y molecules. XPS was implemented to estimate the phase composition of the films. The maximal SEY was found to decrease linearly with the fraction of the graphitic phase in the films. These results are supported by Raman scattering and UPS measurements. The graphitic phase decreases almost linearly for hydrogen and deuterium concentrations between 12% and 46% (at.), but abruptly decreases when the concentration reaches 53%. This vanishing of the graphitic phase is accompanied by a strong increase of SEY and the Tauc gap. These results suggest that the SEY is not dictated directly by the concentration of H/D, but by the fraction of the graphitic phase in the film. The results are supported by an original model used to calculate the SEY of films consisting of a mixture of graphitic and polymeric phases. Full article

Ensuring the energy transition in order to decrease CO₂ and volatile organic compounds emissions and improve the efficiency of energy processes requires the development of advanced materials and technologies for the electrical energy sector. The article reviews superconducting materials, functional nanomaterials used in the power industry mainly due to their magnetic, electrical, optical, and dielectric properties and the thin layers of amorphous carbon nitride, which properties make them an important material from the point of view of environmental protection, optoelectronic, photovoltaic and energy storage. The superconductivity-based technologies, material processing, and thermal and nonthermal plasma generation have been reviewed as technologies that can be a solution to chosen problems in the electrical energy sector and environment. The study explains directly both—the basics and application potential of low and high-temperature superconductors as well as peculiarities of the related manufacturing technologies for Roebel cables, 1G and 2G HTS tapes, and superconductor coil systems. Among the superconducting materials, particular attention was paid to the magnesium di-boride MgB₂ and its potential applications in the power industry. The benefits of the use of carbon films with amorphous structures in electronics, sensing technologies, solar cells, FETs, and memory devices were discussed. The article provides the information about most interesting, from the R&D point of view, groups of materials for PV applications. It summarises the advantages and disadvantages of their use regarding commercial requirements such as efficiency, lifetime, light absorption, impact on the environment, costs of production, and weather dependency. Silicon processing, inkjet printing, vacuum deposition, and evaporation technologies that allow obtaining improved and strengthened materials for solar cell manufacturing are also described. In the case of the widely developed plasma generation field, waste-to-hydrogen technology including both thermal and non-thermal plasma techniques has been discussed. The review aims to draw attention to the problems faced by the modern power industry and to encourage research in this area because many of these problems can only be solved within the framework of interdisciplinary and international cooperation. Full article

Herein we investigated hydrophilic surface modification of SiO_x containing amorphous hydrogenated carbon nanocomposite films (DLC:SiO_x) via the use of atmospheric oxygen plasma treatment. The modified films exhibited effective hydrophilic properties with complete surface wetting. More detailed water droplet contact angle (CA) measurements revealed that oxygen plasma treated DLC:SiO_x films maintained good wetting properties with CA of up to 28 ± 1° after 20 days of aging in ambient air at room temperature. This treatment process also increased surface root mean square roughness from 0.27 nm to 1.26 nm. Analysis of the surface chemical states suggested that the hydrophilic behavior of DLC:SiO_x treated with oxygen plasma is attributed to surface enrichment with C–O–C, SiO₂, and Si–Si chemical bonds as well as significant removal of hydrophobic Si–CH_x functional groups. The latter functional groups are prone to restoration and are mainly responsible for the increase in CA with aging. Possible applications of the modified DLC:SiO_x nanocomposite films could include biocompatible coatings for biomedical applications, antifogging coatings for optical components, and protective coatings to prevent against corrosion and wear. Full article