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Fracture strength of silicon torsional mirror resonators fully coated with submicrometer-thick PECVD DLC film
摘要： In this work, we attempted to enhance the torsional fracture strength of single crystal silicon (SCS) resonators for micro mirrors application by introducing a 300 nm-thick diamond-like carbon (DLC) coating. The SCS torsional beams of the resonators were 20 μm wide and 9 μm thick, and fully coated with DLC films using plasma enhanced chemical vapor deposition (PECVD) at three different deposition bias voltages. The resonators were driven by a piezoelectric actuator and their angular amplitude was measured by a custom-made torsional test system. Average nominal torsional fracture strength of DLC coated resonators was 11.1–30.0% higher than that of bare SCS, reaching a value of 2.93 GPa. The torsional fracture strength of resonators exhibited a good agreement with the tensile fracture strength. Deviations in torsional strength were reduced with increasing deposition bias voltage due to the compressive residual stress of DLC films.
关键词： Single crystal silicon,Micro mirror resonator,Diamond-like carbon film,Strength deviation,Torsional fracture strength
更新于2025-09-23 15:23:52
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Diamond like carbon films with embedded Cu nanoclusters deposited by reactive high power impulse magnetron sputtering: Pulse length effects
摘要： In the present study diamond like carbon films with embedded Cu nanoclusters (DLC:Cu films) were deposited by reactive high power impulse magnetron sputtering (HIPIMS). HIPIMS pulse length (pulse on time) effects were considered. The dependence of the chemical composition on pulse length was found. Structure of diamond like carbon matrix of the nanocomposite films studied by Raman scattering spectroscopy has indicated weak increase of the sp3/sp2 carbon bond ratio with HIPIMS pulse length. Studies of the shape and dimensions of copper nanoclusters performed by He ion microscopy have shown that increase of the HIPIMS pulse on time resulted in increased number of the nanoclusters and subsequent increase of the Cu nanoclusters size. Study of optical properties revealed surface plasmon resonance effect in all investigated films. Correlation between the optical absorption spectra and photoexcited charge carrier relaxation time recorded by the pump probe spectroscopy was found. The highest relaxation time was observed at the excitation wavelength close to the absorption surface plasmon resonance peak wavelength The highest maximum relaxation time was observed for the DLC:Cu film deposited by using HIPIMS pulse of 400 μs on time. It was explained by the dependence of the relaxation time on Cu nanocluster size.
关键词： Pulse length,Diamond-like carbon,High-power pulsed magnetron sputtering,Structure,Optical properties,X-ray photoelectron spectroscopy,Copper,Nanoclusters
更新于2025-09-23 15:23:52
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Controlling Silver Ion Release from Ag-Based Nanocoatings by Plasma Surface Engineering
摘要： Environmental surfaces have been widely recognized as an important source of hospital-associated transmissions. A number of silver-based antibacterial coatings have been reported in the literature. However, the success of any antibacterial strategy depends on the ability to control the kinetics of the silver ions released from the coating. The novel strategy proposed in this work is based on plasma surface engineering for a controlled-release of silver ions. Plasma-based nanocoatings, plasma oxidation processes and surface patterning of silver coatings were designed and optimized. Surface analyses such as XPS and AFM, as well as silver ion release over 168 h, was evaluated by MIP-AES. Results showed that surface plasma engineering successfully allow tuning the silver release and bioactivity in Ag-containing antibacterial coatings.
关键词： diamond-like carbon,plasma oxidation,silver release,antibacterial activity
更新于2025-09-23 15:22:29
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Effect of temperature and bias voltage on electrical and electrochemical properties of diamond-like carbon films deposited with HiPIMS
摘要： The relatively high electrical resistivity of diamond-like carbon (DLC) film is one of the main drawbacks when applied in electronic device. In this study, DLC films were synthesized on 304 stainless steels by high power impulse magnetron sputtering (HiPIMS) process and the effect of deposition temperature and bias voltage on the microstructure, electrical and electrochemical properties, hardness and adhesion strength of the DLC films were investigated. The sp2/sp3 ratio of DLC films first decreased then increased and the surface became denser as bias voltage increasing from 0 to -400 V. While the film turned into graphite-like structure and became incompact when deposition temperature rose from 100 °C to 300 °C. The interfacial contact resistance (ICR) got reduced by increasing bias voltage and deposition temperature. However, as the deposition temperature increased to 300 °C the anticorrosion ability and hardness of DLC films deteriorated. The DLC films deposited at 300 °C presented soft and had better adhesion strength than hard DLC films deposited at 100 °C. DLC films deposited at -400 V bias and 300 °C had the lowest ICR while DLC films deposited at -400 V bias and 100 °C had the best performance when ICR, corrosion resistance and hardness were all taken into consideration.
关键词： Electrochemical corrosion,Substrate temperature,High power impulse magnetron sputtering,Interfacial conductivity,Diamond-like carbon,Bias voltages
更新于2025-09-23 15:22:29
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The influence of positive pulses on HiPIMS deposition of hard DLC coatings
摘要： Diamond-like carbon (DLC) coatings were deposited by a novel HiPIMS method that incorporates positive voltage pulses at the end of the conventional HiPIMS discharge. Different positive voltage amplitudes (100, 200, 300, 400 and 500 V) were used to evaluate the effect of this operation mode on the discharge process and the mechanical properties of the deposited DLC coatings. The application of positive pulses was observed to enhance the ionization of both the sputtered carbon and argon species. Mass spectroscopy measurements showed that a larger amount of high-energy C+ ions are generated, with ion energies proportional to the amplitude of the overshoot voltage. The ion bombardment induced by the positive pulses led to higher compressive residual stresses and densification of deposited DLC coatings. Moreover, their Raman spectra exhibited lower D-band and G-band intensity ratios (ID/IG) as the pulses voltage was increased which is indicative of higher sp3 content. Mechanical properties were evaluated by nanoindentation testing and the hardness of the deposited DLC films was observed to increase from 9.6 GPa (for no voltage pulse applied) to 22.5 GPa (for an applied positive pulse voltage of 500 V).
关键词： HiPIMS,Hard coatings,Diamond-like Carbon (DLC),Tribology
更新于2025-09-23 15:21:01
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Ellipsometry - Principles and Techniques for Materials Characterization || Spectroscopic Ellipsometry - Application on the Classification of Diamond-Like Carbon Films
摘要： Diamond-like carbon (DLC) films have been spreading from their theoretical basis to worldwide industrial applications because of their unique properties. Since their properties depend strongly on the conditions of synthesis, the effective classification of DLC films becomes quite necessary. From the ternary phase diagram to the Japan New Diamond Forum standard, the classification attempts are also accompanied by the continuous development of their applications. Generally, the hydrogen content and sp3/(sp2 + sp3) ratio are the primary parameters for their classification. However, researchers are afraid that currently sp3/(sp2 + sp3) ratio estimated included not only network sp3 but also sp3 hybrid carbons in the hydrogen-terminated cluster. Simultaneously, the above classification methods need to use the large equipment, such as the synchronous radiation source. Therefore, to realize more straightforward to classify DLC films efficiently, the optical constants (refractive index (n) and extinction coefficient (k)) have been proposed in 2013 to be effective method to classify the DLC films, for which a lot of considerable discussion in the past ISO/TC-107 meetings has been made. The purpose of this chapter is to introduce the latest developments of optical constants on the classification of DLC films and explore their relationship with the current standard.
关键词： spectroscopic ellipsometry,diamond-like carbon film,classification
更新于2025-09-23 15:21:01
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Kinetics of graphitization of thin diamond-like carbon (DLC) films catalyzed by transition metal
摘要： In this paper, we have studied the kinetics of graphitization at 773K of thin diamond-like carbon (DLC) films coated with minute amount of Ni metallic particles. DLC films are deposited at room temperature by pulsed laser deposition (PLD) on a transparent quartz substrate, and Ni is deposited on the surface of DLC using molecular beam epitaxy technique at room temperature. The ultra-high vacuum thermal (range 573-873K with 60 min annealing treatments) and kinetic (range 30-3760 min at 773K) behaviors of the deposited films are investigated. Surface and interface characterizations indicate that the growth of graphitic sp2 clusters starts at temperatures lower than 573K. The kinetics of graphitization is recorded at 773K. Thus, the continuous growth of graphitic clusters leads to a long-range kinetics. These clusters are responsible for the increase in the electrical conductivity and carrier mobility, reaching values of 6.103 Siemens/cm and 20 V/cm2?s, respectively. This continuous change is not only explained by the nucleation and growth of graphitic clusters, but also by some reorientation of them alongside both the surface and the quartz substrate. The obtained results demonstrate that thermally post-treated catalytic metal/DLC films are promising materials for conductive electrodes and sensing applications.
关键词： Raman spectroscopy,thermal treatment,electric transport measurements,optical transmission and absorption,diamond-like carbon,thin graphite films,pulsed laser deposition,metal catalyst
更新于2025-09-23 15:21:01
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Effects of external magnetic field on the micro-structure of diamond-like carbon film prepared by pulsed laser deposition
摘要： The DLC ?lm was deposited by pulsed laser deposition in an external magnetic ?eld, and its optical property, surface morphology and atomic bonds were researched. The simulated ?ight tracks of the carbon ions in the magnetic ?eld showed that a number of the carbon ions were constrained by the Lorentz force, ?ing onto the substrate and forming the DLC ?lm. The contrast between the micro-structures of the DLC ?lms deposited in or out the magnetic ?eld showed that the external magnetic ?eld changed the expansion of the laser-produced plume and con?ned the surface diffusion of the charged particles on the substrate, improving the content of the sp3 bonds in the DLC ?lm.
关键词： pulsed laser deposition,diamond-like carbon ?lm,external magnetic ?eld,optical property,atomic bond
更新于2025-09-23 15:19:57
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Structural, electrical and mechanical properties of ВС films prepared by pulsed laser deposition from mixed and dual boron-diamond/graphite targets
摘要： Relatively low and high deposition rates of BCх films were realized by pulsed laser ablation of mixed B–diamond and dual B–graphite targets, respectively. Deposition was performed at 500 °C and the rate of film deposition was determined with respect to the number of atomic monolayers (obviously less or more than one monolayer) grown for one laser pulse. In the case of BCх films formation with a low deposition rate, doping with B facilitated the growth of the nanocomposite structure, which possessed an increased fraction of sp3 bonds, a very low electrical resistance, and an improved mechanical performance. The change of the sheet resistance of these films as the temperature was reduced from 300 to 65 K had a metallic character. For about 95-nm-thick films with bulk compositions of BC1.7 and BC0.6, the resistivity at room temperature were approximately equal to 1.5 mΩ·cm, and the lowest resistivity of 0.23 mΩ·cm was detected for B-enriched film at 85 K. With an increase in the B atom concentration in such films, the charge carrier (holes) concentration decreased, and their mobility increased from 180 to 10,500 cm2·V?1·s?1 due to samples cooling. The application of a higher deposition rate from the dual B–graphite target activated surface migration of condensed atoms, which caused the development of granular morphology, the B segregation and the reduction of the sp3 bond fraction. The hardness and electrical conductivity of such films were obviously inferior to those of the films obtained by PLD with a low deposition rate.
关键词： Hardness,Thin films,Resistivity,Pulsed laser deposition,Boron,Diamond-like carbon
更新于2025-09-19 17:15:36
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Sub-micron structuring/texturing of diamond-like carbon-coated replication masters with a femtosecond laser
摘要： Diamond-like carbon (DLC) coatings have very attractive mechanical and tribological properties, i.e. high hardness, low friction and high wear resistance. Therefore, DLC is often used as a solid lubricant in moulds for injection moulding. Laser processing of DLC with ultrashort lasers, i.e. femtosecond lasers, can be performed both at micron and sub-micron scales, namely by producing laser-induced periodic surface structures (LIPSS). In this research, the effects of laser structuring/texturing on DLC properties are investigated. First, the laser-processing parameters were optimised to produce uniform LIPSS without damaging a thin DLC film and then the properties of the textured DLC-coated substrates were studied. It was determined that the tribological properties of the processed surfaces remained unchanged, but the hardness of the structured/textured DLC layers was reduced significantly. Although GAXRD and Raman spectroscopy did not show any significant crystallisation of the DLC coating after the laser irradiation, the analysis indicated that a thin graphitised layer had been formed on the surface as a result of the femtosecond laser processing.
关键词： Laser microprocessing,Femtosecond laser,LIPSS,Diamond-like carbon (DLC)
更新于2025-09-19 17:13:59