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Diamond-like carbon coatings containing Si and O (a-C:H:SiOx) were deposited onto 316L steel and silicon wafer substrates using a mixture precursor of hexamethyldisiloxane (HMDSO) and acetylene under a high bias voltage. Then, the coated coupons were annealed in an argon media. The hydrogen content in the coating was measured by 2 MeV 4He+ elastic recoil detection analysis (ERDA). The structure and morphology evolution during annealing were characterized by scanning electron microscopy (SEM), mass spectrometry (MS), Fourier transformation infrared spectroscopy (FTIR), Raman spectra, and X-ray photoelectron spectroscopy (XPS). The mechanical properties were investigated using a residual stress tester and nanoindentor. The results showed that under a high bias voltage a large amount of the hydrogen of the a-C:H:SiOx coatings did not bond with carbon. Si and O preferred to form Si C bonds and Si O bonds respectively to enhance C sp3 fraction, relax the residual stress, and depress the graphite cluster growth. During annealing, combining with C sp3 rehybridization, the transformation of the Si C bond to Si O or Si-C-O bonds caused hardness and residual stress variation. The a-C:H:SiOx coatings still held more than 12 GPa hardness after annealing at 590 °C for 4 h, while the hardness was approximately 8 GPa for the pure a-C:H coating.

Deposition of superhydrophobic coatings on glass substrates from hexamethyldisiloxane (HMDSO) precursor using an argon plasma jet at a relatively low power frequency (11.5 kHz) was studied. The coating hydrophobicity was first found to be strongly dependent on the gaseous shield. Nitrogen (N2) rather than inert gases (argon, Ar, and helium, He) had an excellent shielding effect against the interference of ambient air on the plasma jet. The evolution of water contact angle (WCA) of the prepared coating was investigated upon the variations of the operating parameters, such as N2/Ar ratio, HMDSO concentration, deposition time and nozzle-to-substrate distance. Generally, the measured WCA gradually increased with increasing the values of these parameters and then leveled off at some specific values, except for the nozzle-to-substrate distance. The wettability of glass was completely switched from hydrophilicity to superhydrophobicity with the WCA reaching 168° and the sliding angle of about 3° at optimum conditions. The surface morphology analyses by scanning electron microscopy (SEM) and atomic force microscopy (AFM) revealed that the prepared coating had a very high surface roughness and micro-nano structure, which intensely promoted the water repellence property. The chemical examination by X-ray photoelectron spectroscopy (XPS) clearly showed the shielding effect on the surface chemical composition of the coating. N2 shield preserved a high carbon content (in CH3 groups) from the precursor, while minimizing the incorporation of oxygen into the coating surface. Also, it was found that O (from O and OH radicals) has replaced C to form silica-like coating in case of without shielding gas or with Ar and He shields.

This study developed a surface modification technique to obtain nearly superamphiphobic films on AISI 304 stainless steel substrates, which are usually made into dental appliances in orthodontics for malocclusion. Direct fabrication of micro- and nanoscale roughened surfaces on stainless steel substrates were treated using femtosecond laser (FL) processing. Subsequently, pulsed plasma polymerization (P3) was adopted using hexamethyldisiloxane (C6H18OSi2) and octafluorocyclobutane (C4F8) as the precursors to deposit siloxane and fluorocarbon stacking films. The surface characteristics of the deposited films were examined, and in vitro cytotoxicity and antimicrobial tests were performed. Experimental results showed that the surfaces treated by FL and P3 processes exhibited nearly superamphiphobicity with water apparent contact angle (CA) 160°, advancing CA 161°, receding CA160°, contact angle hysteresis (CAH) 1°; sunflower oil apparent contact angle 146°, advancing CA 141°, receding CA137°, CAH 4°; and hexadecane oil apparent contact angle 124°, advancing CA 118°, receding CA113°, contact angle hysteresis CAH 5°, respectively. The nearly superamphiphobicity are attributed to the synergistic effects of pre-roughening by the FL process and post-flourinating with siloxane and fluorocarbon coating by the P3 process, which were consistent with the results of scanning electron microscopy, energy-dispersive X-ray spectroscopy and Fourier transform infrared analyses. In addition, the steel wool abrasion test exhibited the film's surface wear resistance, and in vitro tests revealed the film's non-cytotoxicity and effective inhibition of bacterial growth. Thus, the nearly superamphiphobic coating may be beneficial for applications in orthodontics.

A combined hydrothermal and sol-gel method has been developed to fabricate superhydrophobic coatings on zinc substrate. A double-layered structure of ZnO/SiO2 nanorods and sub microtubes was obtained first on the surface of zinc substrate by the hydrothermal treatment. Then the effects of the Hexamethyldisiloxane (HMDS) and Tetraethoxysilane (TEOS) concentrations in the modification solution on the surface morphology, water repellency and corrosion resistance of the prepared surfaces were carefully studied. The results show that the water repellency of the surface depends largely on the molar ratio of HMDS/TEOS in the modification solution. When the molar ratio was 2, a layer of SiO2 gel was deposited on ZnO nanorod-sub microtube structure to form ZnO/SiO2 core/shell nanorod-sub microtube structure. The prepared superhydrophobic coating had a maximal water contact angle of 152° and a best corrosion resistance since the coating was unwetted in the corrosion solution and could prevent the corrosion media from penetrating into the zinc substrate.

Fragment ions produced from hexamethyldisiloxane (HMDSO) with a hot tungsten wire in a Freeman-type ion source were studied using a low-energy mass-selected ion beam system. The mass numbers of the fragment ions were identified. Although the chemical formulae of these fragments were not completely identified yet, the possible candidates of dominant fragment ions were H + , H 2 + , H 3 + , C + , CH 3 + , O + , Si + , C 3 H 3 + , SiO + , SiC 2 + , SiOCH 2 + , SiC 3 H 9 + , Si 2 OCH 3 + , Si 2 OC 2 H 7 + , Si 2 OC 3 H 9 + , Si 2 OC 4 H 11 + , and Si 2 OC 5 H 15 + . The rates of ion fragment production strongly depended on the tungsten temperature. Among those fragment ions, SiO + ions were mass-selected. The ion energy was approximately 50 eV. Then, the SiO + ions were irradiated to substrates and resulting deposited films were analyzed. Following the completion of the ion irradiation experiment, X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy measurements of the films demonstrated the occurrence of silicon oxide deposition. We conclude that the irradiation of the mass-selected SiO + ions, obtained from HMDSO, to substrates is useful for the secure growth of silicon oxide films.

This work examines the synthesis of nanocomposite thin films on wood (sugar maple, Acer saccharum , Marsh) surfaces via a one-step process in an atmospheric pressure dielectric barrier discharge (DBD). More specifically, ZnO-SiO 2 nanocomposite coatings are obtained from the atomization in the DBD reactor operated in N 2 /N 2 O (Townsend discharge) of a stable colloidal suspension. This suspension is made of crystalline ZnO nanoparticles (NPs) dispersed in hexamethyldisiloxane (HMDSO) and pentane (Pe). Scanning electron microscopy (SEM) combined with energy dispersive X-ray spectroscopy (EDS) show ZnO agglomerates well embedded into a dense SiO 2 matrix. The chemical composition and the thickness of the matrix is analyzed through Fourier transform infrared spectroscopy (FT-IR) coupled to ellipsometry measurements. SEM further reveals a lumpy morphology; a feature ascribed to the intrinsic roughness of the wood samples.

Silver nanoparticle-based antibacterial nanocomposite coatings were fabricated by means of gas aggregation source of Ag nanoparticles and plasma-enhanced chemical vapour deposition of matrix material. Combination of these techniques makes it possible to independently control the amount of Ag nanoparticles in the nanocomposites, as well as properties of matrix material, such as its chemical composition or wettability. This subsequently enables to tune kinetics of silver ion release and hence the antibacterial performance of produced nanocomposites. Based on detail measurements of silver ion release from Ag/plasma polymerized hexamethyldisiloxane and Ag/SiOx nanocomposites, it may be concluded that the release rate is strongly dependent both on matrix material and amount of Ag nanoparticles present in the nanocomposite. These measurements are furthermore accompanied with tests focused on the evaluation of antibacterial potency of produced nanocomposites.

This study focuses on the SiOx:C thin films on polyethyleneterephtalate (PET) produced by radio-frequency (RF) magnetron sputtering with hexamethyldisiloxane (HMDSO). Silicon atoms are inserted into SiOx:C thin films using a silicon target to improve the gas barrier property. Since inserting Si atoms into SiOx:C thin films can reduce the number of pores and increase the density of the film. This process has two benefits. First, it can be easily combined with sputtering processes to produce a multilayer film; and second, it can be performed at low pressures (~ 10 − 1 Pa) to improve the quality of the plasma polymer film. A more linear-like structure and a less cage-like structure is associated with higher density of SiOx:C thin films. The average transmittance of the films thus obtained exceeds 91% in the wavelengths of visible region, and the lowest water vapor transmission rate achieves 0.076 g/m 2 /day. It is about one fourth of the optimum WVTR value (0.3 g/m 2 /day) of a single layer of SiOx:C thin film fabricated with HMDSO at present.

Silicon is considered as a unique, the most effective and interesting doping element that makes the diamond-like carbon coatings promising material for a variety of technical and medical applications. For CVD processes, the most popular silicon precursors are silane and tetramethylsilane (TMS) in combinations with methane, benzene or acetylene. Considerably less attention is paid to the other precursors of silicon, namely, these containing oxygen, particularly hexamethyldisiloxane (HMDSO). Despite few reports in this subject, so far there is a lack of the comprehensive presentation of the influence of the working gas mixture and process parameters on the overall properties of obtained layers. This work is related to in-depth analysis of the topography, morphology, chemical structure and composition of a-C:H:SiO x layers, produced using wide range of process parameters, that is based on the scanning electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy and atomic force microscopy. Results of the analysis show that the morphology, chemical structure and phase composition of synthesized layers depend on the applied negative bias potential and working atmosphere, wherein this correlation is not always straightforward.

Metalloporphyrins are embedded in an organosilicon matrix by an easily up-scalable atmospheric pressure dielectric barrier discharge method. The integrity of the metalloporphyrins, followed by UV–visible spectroscopy, is successfully preserved and their aggregation prevented. The single molecule properties, rather than the bulk ones, are thus enhanced. Exposure to triethylamine, which reaches the metalloporphyrins through the pores of the organosilicon membrane, led to a shift in the absorption spectrum and confirms the gas sensing potential of such coatings.

Mixtures of hexamethyldisiloxane (HMDSO) and oxygen have been used for deposition of SiO 2 -like layers by plasma polymerization under low-pressure conditions onto polyethylene and polystyrene used as basecoat. Water glass was cast onto these 0.5 μm plasma thick siloxane-like layers with a thickness of 5 to 40 μm. The adhesion of these bilayer systems and their flame resistance were tested. The effect of different plasma parameters such as monomer/gas ratio, pressure and power input into the discharge on the deposition rate and the composition of the formed layers was studied. Characterization and chemical composition of the formed films were performed using infrared, X-ray photoelectron and solid state nuclear magnetic resonance spectroscopy. Peel strengths of composites were measured and the locus of peel front propagation was detected. Thermal properties of composites were analyzed by thermo-gravimetric analysis. Finally, the fire-retardant properties of thick coated polymers were determined by exposure to flames and the behavior of coatings on the polymers during flaming was observed visually.

In this work we present the influence of carrier gases in the deposition of low-pressure discharge plasma of hexamethyldisiloxane (HMDSO). Plasma polymerized HMDSO films were deposited with an inductively-coupled discharge reactor using Ar and O2 as carrier gases. The films deposited in Ar contained polymeric structure in the form of SiOxCyHz and could significantly improve the barrier to water vapor of poly(lactic acid) (PLA). The SiOx-like structure of HMDSO films was obtained when using O2 as the carrier gas. However, the films supported some state of residual stress leading to film failures and a significant loss of barrier performance of PLA. The formation of organic and inorganic contents in the films was confirmed by X-ray photoelectron spectroscopy (XPS). The discharge power had an effect on the topography of the films. Rough surface with coarse texture was obtained when the process was done in Ar at high discharge powers. On the other hand, the deposition process in O2 induced smoother surface of plasma‐polymerized films.

In this paper Ag/SiOx nanocomposites are fabricated by inductively coupled plasma (ICP) assisted magnetron sputtering technology. During the deposition of matrix the monomer hexamethyldisiloxane (HMDSO) was flowed into the chamber for SiOx deposition; Ar ions generated in plasma sputtered target to emit Ag nanoparticles. The role of processing parameters, ICP power and the deposition time, on the microstructures and properties of nanocomposites was then investigated in this work. Through FTIR, UV–Visible chemical structures of the nanocomposite Ag/SiOx were characterized; the Ag status in the surface was analyzed by XPS; the morphology of the matrix was detected by AFM and SEM; and the Ag particle size and crystalline were measured by HRTEM and XRD, respectively. As an application the antibacterial behavior of Ag/SiOx nanocomposites was also examined in this paper.

The atmospheric pressure glow discharge burning in argon with small admixture of oxygen and hexamethyldisiloxane is used for the deposition of organosilicon and SiO x -like films on the stainless steel surface. The organosilicon film has high growth rate (85 nm/min) and extremely low surface roughness (0.8 nm), while the SiO x -like film shows relatively low growth rate (40 nm/min) and higher surface roughness (9 nm). The surface wettability, microhardness and the corrosion resistance of the deposited siloxane films are detected. The organosilicon film is hydrophobic (contact angle: 98°) and soft (microhardness: 0.68 GPa), while the SiO x -like film is hydrophilic (contact angle: 45°) and hard (microhardness: 7.85 GPa). The potentiodynamic polarization tests show that by depositing siloxane films on the surface, the corrosion resistance of the stainless steel in the Hanks solution can be largely improved. In particular, the SiO x -like film exhibits better corrosion resistance than the organosilicon film.

Atmospheric pressure dielectric barrier discharge depositions on aluminium of octamethylcyclotetrasiloxane and decamethylcyclopentasiloxane were investigated. Scanning Electron Microscopy and Transmission Electron Microscopy revealed the formation of dense and defect free layers while Fourier Transform Infrared Spectroscopy and X-ray Photoelectron Spectroscopy analyses indicated the formation of highly cross-linked siloxane layers. The corrosion protection afforded by such films was investigated by electrochemical techniques and relationships between the deposition parameters, film chemistry and electrochemical properties of these films are reported. The corrosion performances of films grown from the two cyclic siloxane precursors were shown to be significantly higher than the ones achieved by the films grown from hexamethyldisiloxane in previous work.

We investigated the local deposition of silicon oxide on silicon wafers and glass substrates utilizing a 2.45 GHz microwave-driven plasma jet, which was operated in ambient air with helium and small admixtures of hexamethyldisiloxane (HMDSO). The deposited material was characterized by FTIR, ellipsometry, wear measurements and ERDA. It has been shown that silicon oxide layers are homogeneous, stoichiometric and free of carbon. An established dwell time method allowed precise local deposition of films and analogous structures which were transferred into the substrate bulk material using ion beam techniques or mechanical polishing. Shape-preserving transfers have been successfully conducted.

This paper focuses on some of the most debated issues concerning the utilization of atmospheric pressure dielectric barrier discharges (DBDs) in surface processing of materials such as, for instance, the existence of different discharge regimes (filamentary and homogeneous) and the influence on the discharge behaviour of feed gas additives and substrate properties (chemical composition, electrical characteristics, etc.). Crucial aspects of the DBD operation which highly differentiate this approach from the well established low pressure plasma technology will be discussed. An overview of the state of the art in atmospheric pressure thin film deposition from fluorocarbon- or organosilicon-containing DBDs will be also provided. In particular the possibility of tailoring the chemical composition of the coatings, the etching–deposition competition and the influence of feed gas contaminants (i.e. air and H 2 O) in the deposition of fluoropolymers will be discussed. Recent results on the deposition of SiO x C y H z thin films from three different methyldisiloxanes (i.e. hexamethyldisiloxane, pentamethyldisiloxane and tetramethyldisiloxane) will allow to highlight the effect of the chemical structure of the organosilicon precursor and of the oxygen-to-methyldisiloxane feed ratio on the properties of the deposits. The results obtained through different diagnostic techniques of the plasma phase (i.e. optical emission spectroscopy and GC–MS analysis of the exhaust gas) and of the deposits (i.e. XPS, FT-IR, SEM, and WCA) allow to highlight interesting aspects of the fluorocarbon and organosilicon plasma chemistry at atmospheric pressure.

Plasma-assisted chemical vapour deposition (PACVD) siloxane coatings from a mixture of hexamethyldisiloxane (HMDSO) and O 2 , and hybrid coatings deposited by simultaneous sputtering of silicon and plasma polymerisation of HMDSO + O 2 were prepared on glass and steel substrates. The effect of the addition of sputtered silicon was investigated for coatings with different HMDSO/O 2 ratios. The microstructure and composition of coatings were affected by the coating parameters used. Silicon content was roughly the same for all coatings; carbon content decreased while oxygen content and surface energy increased with decreasing HMDSO/O 2 ratio in hybrid coatings. Hardness and modulus were higher for hybrid coatings and increased with decreasing HMDSO/O 2 ratio. Hybrid coatings showed much better scratch and wear resistance than PACVD coatings. All coatings showed good fouling-release performance with the freshwater bacterium Pseudomonas fluorescens .

This study evaluated the use of pin-on-disc wear testing as a technique to examine the mechanical behaviour of nanometre thick plasma deposited coatings. The coatings were deposited onto polyethylene terephthalate and silicon wafer substrates by directly injecting an aerosol of siloxane liquid precursors into a helium/oxygen atmospheric pressure plasma. The siloxane precursors examined were hexamethyldisiloxane, polydimethylsiloxane and tetramethyldisiloxane. The mechanical performance of 21 (± 3) nm thick coatings was compared using a pin-on-disc wear test technique and fragmentation tests. An increase in the level of precursor plasma exposure was found to be associated with an increase in coating surface energy and a reduction in coating roughness and resulted in enhanced wear resistance. Fragmentation tests revealed a transition from ductile failure to brittle failure as the level of plasma exposure increased. This correlated with the reduction in coating wear rates. Wear track depth and proximity to the coating/substrate interface were both found to influence the rate or wear. A simple correlation between wear rate and applied force is presented as a method for comparing coating performance using pin-on-disc wear testing.

Recently, plasma-polymerization at atmospheric pressure has become a promising technology due to its reduced equipment costs and its possibility of in-line processing. This paper focuses on plasma deposition by an atmospheric pressure dielectric barrier discharge (DBD) using hexamethyldisiloxane (HMDSO) as gaseous precursor. HMDSO plasma-polymerized films are deposited onto polyethylene terephthalate (PET) films using argon and different argon/air mixtures as carrier gases. The chemical and physical properties of the obtained coatings are discussed using contact angle measurements, Fourier transform infrared spectroscopy (FTIR) and atomic force microscopy (AFM). Contact angle and FTIR results show that the composition of the gas phase and the chemical structure of the obtained coatings are clearly correlated. When pure argon is used as working gas, the film is polymeric with a structure close to [(CH3)2–Si–O]n. However, with increasing air content, a gradual change is observed from organic polydimethylsiloxane-like coatings to inorganic, quartz-like deposits. AFM results clearly indicate that with increasing air content, the deposition rate decreases, while the surface of the deposited films becomes rougher. From this point of view, the capability of controlling both chemical and physical properties of the plasma-polymerized films by varying operation conditions opens interesting perspectives.

It has been reported that plasma treatments are to modify surface properties of polymers such as adhesivity, hydrophliicity and hydrophobicity. The plasma interaction with the surface produces modification of its chemical structure and morphology. In this study, surface modification of polyester fiber with high water-repellency and super-hydrophobic was carried out plasma polymerization coating. Polyester fiber with water-repellency was treated with atmospheric pressure middle frequency (MF) and radio frequency (RF) plasma system using Ar and hexamethyldisiloxane (HMDSO). The Ar gas has been used as carrier gas. The plasma coated PET fiber of HMDSO with water-repellency of 90 rating showed higher water-repellency than untreated PET fiber with water-repellency of 0 rating. The surface morphologies of plasma treated fiber were characterized by scanning electron microscopy (SEM). The Fourier transform infrared (FT-IR) spectrometry analyzed the chemical composition of the polymer surface.

Thin silicon oxynitride (SiO x N y ) has been deposited for a gas barrier layer on the surface of poly(ether sulfone) film using plasma-enhanced chemical vapor deposition (PECVD) of a mixture of hexamethyldisiloxane (HMDSO) and ammonia. The chemical structure of the deposited layer varied from organic to inorganic structures depending on RF plasma input power applied to the reaction system. A silicon-based undercoat layer, which has an organic/inorganic hybrid structure, was used as an interfacial buffer layer between the organic PES and inorganic SiO x N y layer. With the help of the undercoat layer, the dense inorganic SiO x N y layer gave a superior oxygen barrier property of 0.2 cm 3 /m 2 day at a critical coating thickness of ca. 20 nm. In a highly stressed SiO x N y film, the effect of the undercoat layer was remarkable in preventing crack formation during bending tests.

A microwave driven low pressure plasma reactor is developed based on a modified Plasmaline antenna for plasma processing of polyethylene terephthalate (PET) foils and bottles. It allows for the treatment of thermolabile packaging materials, e.g. plasma sterilization and permeation barrier coating. Silicon oxide films are deposited on PET foils as a permeation barrier coating. A pulsed hexamethyldisiloxane:oxygen plasma is ignited under various conditions and the oxygen permeation is investigated. A criterion for the homogeneous deposition of SiO x coatings is described depending on the residence time of process gases. Additionally, the composition of the coatings is analyzed by means of Fourier transform infrared spectroscopy regarding carbon and hydrogen content. A strong relation between barrier properties and film composition is found: good oxygen barriers are observed as carbon content is reduced and films become inorganic, quartz-like. A residual permeation as low as J = 1.0 ± 0.3 cm 3 m − 2 day − 1 bar − 1 for SiO x coated PET foils is achieved. The dependencies of important plasma parameters, such as gas mixture, process pressure, power and pulse conditions on oxygen permeation through packaging foil are shown to optimize the coating process.

Organosilicon plasma polymer layers were deposited by surface dielectric barrier discharge (DBD) at atmospheric pressure, in an attempt to enhance the corrosion protection of a reflective aluminium (Al) layer applied on a polyester (PET) fabric. A number of tests were carried out to characterize the improvement of corrosion resistance – namely sodium carbonate (Na 2 CO 3 ), water vapor and Kesternich tests – as a function of plasma treatment time, type of carrier gas, admixture of oxygen, amount of hexamethyldisiloxane (HMDSO) precursor supplied to plasma and post-plasma-treatment heating. Moreover, plasma-deposited protective films were characterized by the scanning electron microscopy (SEM), infrared spectroscopy (DRIFT FTIR), and X-ray photoelectron spectroscopy (XPS). While aluminium was consumed in the Na 2 CO 3 corrosive solution within a few minutes for the untreated surface, the optimally performing plasma polymerized layers revealed an extraordinary corrosion resistance. Furthermore, the best protective organosilicon coatings showed only a 1–2% absolute reduction of reflection compared to the untreated fabric, over the complete solar spectrum (250–2500 nm).

This study presents results on the humidity-sensing properties of titanium dioxide thin films measured by a quartz microbalance. A novel two-layer structure, consisting of a polymer sub-layer and a sensing titanium dioxide layer, was fabricated on a quartz resonator. The polymer sub-layer was synthesized by a plasma process from hexamethyldisiloxane to protect the resonator's surface during the deposition of the titanium dioxide film by magnetron sputtering. The TiO 2 films were characterized by X-ray diffraction and Auger Electron Spectroscopy. The film composition was determined to be close to that of stoichiometric TiO 2 . The sensitivity to humidity varied from 5 Hz/%RH to 7 Hz/%RH for TiO 2 film thickness lying in the range of 18–70 nm. An increase of film thickness in this interval led to a slight decrease in sensitivity, which is explained by water sorption occurring principally at the surface of the titanium dioxide film and a change of the morphology to a higher surface smoothness for thicker films. It was found that 30–60 min of sorption time is necessary to completely eliminate hysteresis, which suggests that the process is reversible. These results are promising for the development of sensor devices for measuring the relative humidity of air.

Monolithic SiC, SiN x and their duplex SiC–SiN x films were synthesized from hexamethyldisiloxane solution at 750 °C on Si wafer and SUS304 steel substrates using Ar/H 2 /N 2 plasma enhanced chemical vapor deposition (PECVD). The films were characterized by scanning/transmission electron microscopy (SEM/TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Amorphous SiN x films were easily deposited on two kinds of substrates from thermal Ar/H 2 /N 2 plasma, whereas crystalline SiC films synthesized using thermal Ar/H 2 plasma was only achieved on Si substrate and severe etching of the steel substrate by the plasma was observed. By varying N 2 flow rate from 4.5 l/min to zero at the intermediate period of the deposition process, a duplex SiC–SiN x film, consisting of a top SiC and an inner SiN x layer adjacent to the substrate, was obtained both on Si and steel substrates. The corrosive exposure test in KCl atmosphere at 650 °C indicated that the ceramic film-coated steel substrates demonstrated a much superior corrosion resistance in comparison with the uncoated one.

In this research silicon and silicon oxide doped hydrogenated amorphous carbon films have been synthesized by direct ion beam deposition from hexamethyldisiloxane (HMDSO) vapor mixture with hydrogen (H 2 ) or acetylene (C 2 H 2 ) gas. Adherent and stable coatings of the thickness up to 0.8 μm were deposited onto the stainless steel and tooling steel. Presence of a few atomic percents of Si was enough to achieve stable coatings. In the HMDSO+C 2 H 2 film silicon is found in the form of the SiC while in HMDSO+H 2 film Si presents as silicon oxide (SiO x ). Raman spectra of the deposited films were typical for diamond like carbon (DLC). Films deposited from mixture with hydrogen gas had higher optical transparency (E 04 bandgap 3.1 vs. 1.6 eV for film deposited from mixture with acetylene gas) and lower refractive index (1.7 vs. 2.1 at 632.8 nm wavelength). However, more transparent SiO x doped DLC films had more disordered structure as well.

The work investigates the protective properties of polyurethane coil coating with a plasma polymer top layer. Two different gas precursor mixtures [hexamethyldisiloxane (HMDSO)/oxygen and HMDSO/heptadecafluoro-1-decene (HDFD)/Ar] were used for microwave plasma polymer deposition. The barrier properties of the specimens were evaluated by electrochemical impedance spectroscopy (EIS). The evolution of the structure of the plasma polymer-treated coil coating during immersion tests was investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Energy-dispersive spectroscopy (EDS) was used to study the change of the top layer composition with the immersion time. Composition of the coil coating surface after plasma activation procedures was analysed by X-ray photoelectron spectroscopy (XPS). Transmission electron microscopy (TEM) was used to reveal the structure and thickness of the plasma polymer layers. The results show that the plasma treatment procedure causes a deterioration of the barrier properties of the polyurethane coil coating due to the formation of pores in the coil coating. However, the fluorine-containing plasma polymer films (obtained using the HMDSO/HDFD/Ar gas mixture) show enhanced stability and better barrier properties when compared to fluorine-free films (obtained using the HMDSO/oxygen gas mixture). The activation of the coil coatings by oxygen plasma treatment can be responsible for degradation of the barrier properties. The argon plasma activation is less destructive in comparison to the oxygen plasma treatment. The plasma polymer treatment of the coil coating using the fluorine-containing precursor gas mixture can be used for modification of the coil coating surface almost without any degradation of the barrier properties.

The aim of this study is to contribute to the understanding of the thin film growth mechanism using an Atmospheric Pressure Townsend-like Discharge (APTD). Films obtained in dielectric barrier discharges fed with N2 and small admixtures of hexamethyldisiloxane (HMDSO) and nitrous oxide (N2O) as oxidizer gas have been investigated. Results are compared to those obtained with SiH4, in similar conditions. The discharge dissipated power and the feed composition ([N2O]/[HMDSO] ratio) on film properties have been investigated by means of Fourier Transform Infrared Spectroscopy (FTIR), X-ray Photoelectron Spectroscopy (XPS) and Ellipsometry. The film thickness homogeneity and deposition rate have been measured by means of a profilometer and an ellipsometer at the same time. Then silicon oxide thin film properties obtained with SiH4 and HMDSO containing APTD are compared. Concerning chemical composition results are similar. In the two cases, a rather low adding of N2O allows to get SiOx layer without N and C incorporation. Si–OH bounds are always observed. The relative contribution of homogeneous and heterogeneous growth mechanisms is very dependent on the nature of the precursor. Because of its high reactivity, SiH4 induces particles formation in the plasma. These particles are efficiently included in the coating, decreasing drastically the layer density. Thin films made with HMDSO are always dense.

HMDSO plasma polymer films are known to reduce the resulting surface free energy and the permeation rate of water vapour and oxygen through the treated polymer substrates. In this work, plasma polymer films were deposited from hexamethyldisiloxane (HMDSO) on polyethylene terephthalate surfaces under different operating conditions and the resulting surface properties were investigated. The structure and bondings in the deposited films were studied by means of IR spectroscopy. The thickness of the deposited films was deduced observing images acquired with a focused ion beam (FIB). Hydrophobic performances were investigated by means of water droplet contact angle measurements. Correlation between operating deposition conditions and resulting structure and surface properties of the films were also discussed.

The present paper mainly deals with the development and characterization of plasma polymerized SiO x barrier films on polyethyleneterephthalate (PET). Hexamethyldisiloxane (HMDSO) in mixture with oxygen (O 2 ) are used as deposition gases. The chemical composition and the morphology of the films are characterized by infrared absorption measurements and by REM investigations. The oxygen permeability was measured as a function of time with the carrier gas method using a ceramic (ZrO 2 ) detector.

Micro-jet plasma chemical vapor deposition can produce quartz-like localized coatings from HMDSO/O 2 (hexamethyldisiloxane) mixture with an extremely high deposition rate (120 μm/s). The reaction between HMDSO and O 2 takes place in the jet. Less than 0.5 ms is required to remove the methyl groups from the monomer and to oxidize Si. The chemical composition of the product is close to SiO 2 . It was found that the optimal parameters for a well-defined deposition differ with the capillary's inner diameter (ID) and depend strongly on the jet expansion. The lower the background pressure p c related to the capillary exit pressure, the more the jet expands. A small ID requires a relatively high flux and a high p c for a confined jet which, in turn, ask for a high power density for the excitation of the gas.

This study focuses on the water vapor permeability of plasma enhanced chemical vapor deposited (PECVD) silicon oxide (SiO x ) films. A batch reactor equipped with a 2.45 GHz slot antenna plasma source and a 13.56 MHz-biased substrate holder, was used to conduct the experiments. The remote microwave and the direct radio frequency plasma source can be operated separately or in dual mode. An oxygen plasma was generated and hexamethyldisiloxane (HMDSO) used as monomer. The SiO 2 -like films were deposited onto 12 μm PET film. An increase of RF-power input, oxygen-to-monomer flow rate ratio, layer thickness or decrease of process pressure was found to enhance the gas barrier performance. Compared to uncoated PET films, a maximum reduction of more than a factor of 150 has been achieved for water vapor transmission rate.

In this paper first results will be presented concerning our investigations on direct and remote plasma polymerization of SiOx films using a microwave induced PACVD process. The plasma source working at a frequency of 2.45 GHz was a slot antenna type CYRANNUS®-I source which was able to maintain a homogeneous plasma at atmospheric pressure. The carrier and the monomer gases used for the silica deposition were an argon–oxygen mixture or air and hexamethyldisiloxane, respectively. There will be given a description of the deposition conditions in the remote and the direct mode. Depending on the deposition parameters thin and smooth SiOx films on silicon or stainless steel substrates were prepared. The films were characterized by IR spectroscopy, ellipsometry and various microscopic methods like optical microscopy, SEM and HRTEM.

Room-temperature preparation of silicon dioxide films with smooth surfaces and small carbon was achieved by low-energy ion beam induced chemical vapor deposition (IBICVD) with a bubbling system for hexamethyldisiloxane (HMDSO). When prepared using bubbled HMDSO and assisted O2 gas under irradiation of 150 eV Ar ions, the film contained carbon of 0.2% and the root mean square of the surface roughness of the film was 2.0 nm. However, when prepared using the bubbled HMDSO under irradiation of 150 eV oxygen ions, the film contained carbon less than 0.1%, and the surface roughness was 0.25 nm. It is considered that low-energy oxygen ion bombardment promotes not only chemical reaction and dissociation of HMDSO but also reactive ion beam etching on the film surface.

Plasma polymer films were deposited from hexamethyldisiloxane (HMDSO), dichloro(methyl)phenylsilane (DCMPS) and vinyltriethoxysilane (VTEO) on polished silicon wafers using a RF helical coupling deposition system. The composition of elements in the surface region (top 6–8 nm) of the deposited films was studied by X-ray-induced photoelectron spectroscopy (XPS) on an ADES 400 VG Scientific photoelectron spectrometer using MgK α (1253.6 eV) or AlK α (1486.6 eV) photon beams at the normal emission angle. Aging effects of plasma-polymerized (PP) HMDSO and DCMPS films stored under standard laboratory conditions were investigated by employing XPS. Post-deposition contamination and oxidation of pp-DCMPS and pp-HMDSO film was carefully observed. An increase in oxygen atoms on the film surface over time is accompanied by changes in bulk atomic concentrations. Sequential sputtering with an Ar ion-beam, together with XPS analysis, was used to measure concentration depth profiles in pp-HMDSO and pp-DCMPS films.

Hard diamond like carbon (DLC) films with an addition of SiOx were deposited in capacitively coupled rf discharges from a mixture of methane and hexamethyldisiloxane (HMDSO). The flow rate of HMDSO was changed in order to vary the SiOx content in the films. Complete atomic composition of the films was determined by Rutherford backscattering spectroscopy combined with elastic recoil detection analysis. The thickness and the optical properties were obtained from the ellipsometric measurements. The mechanical properties were studied by a depth sensing indentation technique using Fischerscope H100 tester. The O/Si ratio in DLC:SiOx films was 0.286 and the content of SiOx increased with the HMDSO-to-methane flow rate ratio q. The DLC:SiOx films were close to DLC films as concerning the optical properties in the uv/visible and the high hardness if q was maximum 0.25. However, the compressive stress in the films was reduced, the film fracture toughness was improved and the deposition rate increased.

RF excited gas discharges of hexamethyldisiloxane (HMDSO) with and without oxygen and methane (CH4) without further carrier gas were examined to identify reaction parameters determining deposition rate and film properties of SiOx and a-C:H films, respectively. This evaluation is supported by the used reactor type which enables well-defined deposition conditions. Both symmetrical and asymmetrical electrode configurations are investigated. It is found that the deposition rate depends on the reaction parameter power input per gas flow where the gas flows of monomer and reactive carrier gases are added. Thus, O2 in conjunction with HMDSO can be considered as a film-forming gas. Even in asymmetrical discharges the concept of the reaction parameter W/F holds, as long as the increasing ion bombardment allows a continuous film growth. While W/F controls the chemical composition of the films, the potential drop across the plasma sheath influences the mechanical film properties. With these findings SiOx and a-C:H plasma coatings can be designed.

The study presents diagnostic results from a hexamethyldisiloxane/oxygen/argon deposition plasma. The plasma was excited by microwaves using a slot-antenna device. We mainly used Fourier transform infrared spectroscopy to monitor molecule/radical concentrations. Additionally cavity ringdown spectroscopy was set up to determine absolute atomic silicon densities. The measurements were performed in the downstream region of the reactor. By studying the correlation between radical concentrations in the plasma and different input gas compositions we could identify relevant reaction pathways. It is concluded that oxygen is not only involved in the usual oxidation channels but also in breaking the siloxane bond. Consequently, siloxane polymerization occurs mainly on the surface and not in the plasma volume. Another unexpected feature concerns the indirect production of methane by reactions, which can also be controlled through the oxygen concentration.

Hard silicon nitride-like coatings have been grown in a high-density microwave electron cyclotron resonance discharge, using hexamethyldisiloxane (HMDSO) as the deposition precursor and ammonia as the reactive gas. Statistical experiment design methodology was used to investigate the effects of microwave power and NH 3 /HMDSO flow-rate ratio on the growth rate, elastic modulus and hardness of the plasma-grown coatings. The films deposited are hard, colorless and transparent, with growth rates of up to 0.5 μm/min. Films lasted 745–840 h in an ASTM B117 salt-fog corrosion test. X-Ray photoelectron spectroscopic analyses showed the coating composition to be SiC x O y N z , with significant carbon and up to 13.7 at.% nitrogen concentration. While not stoichiometric Si 3 N 4 , coatings grown at high microwave power and high NH 3 /HMDSO flow ratios had an elastic modulus of 176 GPa and hardness of 12.2 GPa, comparable to values reported for thermally grown silicon nitride.

The corrosion-protective performance of plasma-polymerized (PP) coatings on aluminium substrates has been investigated by potentiodynamic (cathodic) polarization curve measurement, X-ray photoelectron spectroscopy (XPS) and temperature-programmed photoelectron emission (TPPE) measurement. PP films from tetraethoxysilane (TEOS)/O 2 , hexamethyldisiloxane/O 2 and cyclohexane were deposited on previously argon plasma treated aluminium substrates by a 13.56 MHz radiofrequency generator. The weight loss rate obtained from the cathodic polarization curve for the PP film samples utilized as the working electrode was employed to evaluate the corrosion-protective performance. The PP films of TEOS/O 2 mixtures gave the best protective performance. The corrosion potential for all the PP films became more negative than that for the substrate only. The XPS analysis indicated that TEOS films have a chemical structure like SiO 2 . The TPPE analysis revealed that the argon plasma pretreatment of the metal substrate enhances greatly the ability of the surface to emit electrons.

We studied a homogeneous atmospheric pressure dielectric barrier discharge in helium with small admixtures ( −3 ) of hexamethyldisiloxane (HMDSO) vapor for the deposition of thin silicon organic films on a technical aluminum sheet metal. The powered (100 kHz) plane electrode (80×15 mm 2 ) is covered by a glass insulator layer. Power absorption, sustaining voltage (2 kV pp ), gap voltage (700 V), current density (∼20 mA cm −2 ), and total light emission are monitored to characterize the discharge in the gap (1–1.5 mm). The gas composition of the exhaust gas is studied by mass spectrometry. During discharge operation a decrease of the precursor concentration is observed, due to dissociation and thin film deposition. Typical deposition rates range from approximately 0.2 to 2.0 nm s −1 , as measured by substrate weighing. The films display water contact angles of 63±3°. A protection of the Al sheet metal against 0.1n-NaOH for 3 min is observed. FT–IR (dominant SiOSi band) and XPS (low C content) measurements both reveal the dominance of non-organic components in the film. The spatially averaged electron concentration (2×10 11 to 5×10 11 cm −3 ) is experimentally determined by heterodyne interferometry. Discharge properties and thin film deposition are discussed in relation to the ionization rate of the precursor molecules and the current density.

We deposited protective coatings on polycarbonates from hexamethyldisiloxane (HMDSO) and HMDSO/O2 mixtures by the plasma enhanced CVD method. In particular, we studied deposition rate, optical constants in UV/VIS, film composition and mechanical properties dependent on rf power and oxygen to HMDSO flow rate ratio. Plasma polymer HMDSO films (PP-HMDSO) showed good transparency in the visible and increased absorption in UV region. The optical constants of HMDSO/O2 films were similar to the tabulated SiO2. In general, the films were characterised by a relatively high content of hydrogen (22–66%) and a carbon content below 20%. The films deposited at an oxygen-to-HMDSO flow rate ratio higher than 15 exhibited higher tensile stress and higher hardness than those prepared at ratios of 5–10. The nature of the internal stress changed to compressive for PP-HMDSO. Plasma pre-treatment of polycarbonate in argon significantly improved the film adherence, especially when low powers and short treatment times were used.

We report on the microwave plasma-enhanced chemical vapor deposition (PECVD) of silicon dioxide from oxygen/tetraethoxysilane and oxygen/hexamethyldisiloxane under continuous wave and pulse modes. The influence of process parameters such as oxygen/organosilicon flow rate ratio, pressure and microwave power on the film characteristics has been investigated. We were interested in the film deposition rate, density, refractive index and atomic concentrations. Mass spectrometry and Langmuir probe measurements provided useful information about the gas phase and the plasma discharge. A comparison was made between the properties of films deposited with continuous wave and with equivalent powered pulsed plasma. The effect of the pulse frequency and of the pulse duty cycle was also studied.

Hexamethyldisiloxane/oxygen fed radiofrequency glow discharges have been utilised for the deposition onto polyethyleneterephtalate of transparent silicon dioxide-like films with barrier properties to oxygen. The complexity of such plasma phases and the increasing interest shown for the industrial deposition process of barrier films have led the authors to investigate Fourier transform infrared absorption spectroscopy as a plasma technique for better understanding of the deposition mechanism and the development of a process control useful for scaling up. The above mentioned technique has shown its potential in the correlation of plasma phase chemistry with the barrier properties of the SiOx coated polymer, especially when very good performances are required (OTR≤3 cm3/m2 day atm).

Si-containing gas-separating membranes, produced by conventional chemical methods, demonstrate a high level of gas permeability. The plasma polymerization technique was used for membrane preparation from hexamethyldisiloxane (HMDSO). Plasma polymers were deposited under extremely different conditions. The gas-separating properties and surface morphology of the prepared membranes were investigated. The surface morphology depends strongly on the substrate surface: the plasma polymer on the porous substrate has a hemispherical macrostructure. The composite membrane with plasma polymer has permeability coefficients of the tested gases (O 2 , N 2 , He) comparable with those of the most permeable membrane produced by chemical methods. Such composite membranes demonstrate the higher selectivity for He/N 2 gas pair.

Thin organosilicon films doped with gadolinium were prepared by plasma chemical vapor co-deposition (13.56 MHz) using hexamethyldisiloxane as a precursor for the light-guide matrix, and tris(2,2,6,6-tetramethyl-3-5-heptanedionato)gadolinium(III) as a source of luminescent centers. The chemical composition of such films was investigated by Fourier transform infrared spectroscopy and quantitative microanalysis. Measurements of optical (ultraviolet–visible) absorption and photoluminescence were also performed. It was found that the optically active centers are created by Gd 3+ ions bonded to the matrix via oxygen atoms. The center excitation consists of a non-radiative transfer of energy absorbed in the matrix (200–230 nm) to the ion. The emission light observed at 312 nm is attributed to the 6 P 7/2 → 8 S 7/2 transition in Gd 3+ .

By means of plasma polymerisation, thin films from siloxanes feeds [octamethylcyclotetrasiloxane (OMTS) and hexamethyldisiloxane (HMDSO)] were deposited onto single-crystal quartz resonators with a frequency of oscillation of 5 MHz, and the amount of adsorbed vapour, which is proportional to its volume concentration, was determined from the change in frequency. Selective sorption of inhalant anaesthetics was achieved by annealing quartz resonators covered by poly(OMTS) at 100–200 °C. The measurement was carrried out in a dynamic regime in such a way that the vapour of the substance to be measured was brought to the resonators by a carrier gas (air, N 2 , N 2 O). The concentration of anaesthetic vapour measured in the carrier gas varied from 0.25 to 5.0 vol.%, and in H 2 O vapour from 1% to 90% relative humidity. The designed system can be applied in practice in anaesthesiology.

The microwave-plasma assisted deposition of hexamethyldisiloxane [HMDSO-(CH 3 ) 3 SiOSi(CH 3 ) 3 ] plasma polymer (PP) films for corrosion protection of Al sheet metal surfaces was investigated. Ar, O 2 and H 2 carrier gases at flow rates up to 150 sccm and microwave power densities up to 5 W/cm 2 were used. The process pressure was varied between 1.5 and 3.7 mbar. A mass spectrometer was used to monitor the exhaust gas composition and the monomer decomposition. FTIR and XPS measurements were used to characterize the highly cross-linked PP-HMDSO layers. The deposited films exhibited corrosion protection properties similar to those observed for specially prepared evaporated Al films with a chemical resistance to a 1.0 mol/l NaOH solution. Also, the adhesion of the coating to the substrate was good. The polymer layers (thickness ∼ 1 μm) were found to be quite chemically homogenous. Static contact angles

Thin films with hydrophobic character are required for many applications, e.g., as diffusion barrier or as corrosion protection. These properties can be realized by plasma polymerization of fluorocarbon monomers such as C 4 F 8 to produce homogeneous layers of PTFE-like structure. Plasma polymerization requires plasma sources with high deposition rates even when processing thermally unstable substrates or those that absorb RF power. Furthermore, excellent film homogeneity is often needed when coating large surface areas. Here we characterize a radio frequency (RF) remote process to deposit such films where discharge and processing zone are separated. As primary discharge we use a novel, linear, hollow-cathode RF plasma source. The feasibility for homogeneous large-area deposition has already been demonstrated for organosilicon compounds (HMDSO). In this paper the remote polymerization of C 4 F 8 is characterized. Geometric effects are discussed as well as the influence of excitation power and gas flows on the process. Deposition rates of 160 nm min −1 and a homogeneity of ±2% over a linear dimension of 250 mm are realized. Contact angles of up to 120 correspond to those on conventional poly(tetrafluoroethylene) (PTFE). The refractive index of the films was determined to 1.375 ±0.025. Fourier transform infra-red spectra proved the existence of PTFE-like structures.