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Silicon (Si) thin films were produced using an aerosol assisted atmospheric pressure chemical vapor deposition technique with liquid hydrosilane precursors cyclopentasilane (CPS, Si5H10) and cyclohexasilane (CHS, Si6H12). Thin films were deposited at temperatures between 300 and 500 °C, with maximum observed deposition rates of 55 and 47 nm/s for CPS and CHS, respectively, at 500 °C. Atomic force microscopic analyses of the films depict smooth surfaces with roughness of 4–8 nm. Raman spectroscopic analysis indicates that the Si films deposited at 300 °C and 350 °C consist of a hydrogenated amorphous Si (a-Si:H) phase while the films deposited at 400, 450, and 500 °C are comprised predominantly of a hydrogenated nanocrystalline Si (nc-Si:H) phase. The wide optical bandgaps of 2–2.28 eV for films deposited at 350–400 °C and 1.7–1.8 eV for those deposited at 450–500 °C support the Raman data and depict a transition from a-Si:H to nc-Si:H. Films deposited at 450 oC possess the highest photosensitivity of 102–103 under AM 1.5G illumination. Based on the growth model developed for other silanes, we suggest a mechanism that governs the film growth using CPS and CHS.

Zinc oxide (ZnO) and aluminum-doped zinc oxide (AZO) thin films were deposited via atmospheric pressure plasma enhanced chemical vapor deposition. A second-generation precursor, bis(1,1,1,5,5,5-hexafluoro-2,4-pentanedionato)( N , N ′-diethylethylenediamine) zinc, exhibited significant vapor pressure and good stability at one atmosphere where a vaporization temperature of 110 °C gave flux ~ 7 μmol/min. Auger electron spectroscopy confirmed that addition of H 2 O to the carrier gas stream mitigated F contamination giving nearly 1:1 metal:oxide stoichiometries for both ZnO and AZO with little precursor-derived C contamination. ZnO and AZO thin film resistivities ranged from 14 to 28 Ω·cm for the former and 1.1 to 2.7 Ω·cm for the latter.

Amorphous hydrogenated silicon-based multilayer coatings were deposited on 301 stainless steel (SS301) and Ti–6Al–4V alloy substrates using plasma enhanced chemical vapor deposition (PECVD), in order to integrate the advantages of the respective layers. Corrosion and tribo-corrosion behaviors of the complete coating/substrate system on different substrates were investigated. The SiN/SiC double-layer coating substantially improved the corrosion resistance of the metals: For SS301, the corrosion current, i corr , was reduced by more than three orders of magnitude, and the breakdown voltage was increased from 0.34 to 1.37 V. For Ti–6Al–4V, the i corr was decreased by a factor of ~ 50. Particularly, the Ti–6Al–4V/SiN/SiC multilayer system exhibited excellent anti-corrosion properties according to potentiodynamic polarization measurements, due to the superior corrosion resistance of both the Ti–6Al–4V substrate and the silicon-based coatings. Further enhancement of the tribo-corrosion resistance has been achieved by applying an amorphous hydrogenated carbon (a-C) coating as a top layer in the three-layer system. In the tribo-corrosion test in 1 wt.% NaCl solution, the SiN/SiC/a-C coating reduced the wear rate and the friction coefficient by a factor of ~ 175 and ~ 4, respectively, compared with the bare Ti–6Al–4V. The Ti–6Al–4V/SiN/SiC/a-C multilayer system integrates in synergy the advantages of the respective layers, and its versatility makes it a particularly attractive candidate for applications in different harsh working environments.

Applications of hard protective nanocomposite coatings are frequently limited by insufficient adhesion related to high stress. In the present work, we study the effect of an intermediate Cr layer on top of the stainless steel 410 (SS410) substrate on the performance of the nanocomposite (nc) TiN-based coatings prepared by plasma enhanced chemical vapor deposition. The Cr layer was found to enhance the corrosion resistance of the SS410 substrate by a factor of 280 in terms of corrosion current, and to increase adhesion of the TiN coating by a factor of 4. We show that for the nc-TiN/a-SiNx and nc-TiCN/a-SiCN coatings, the substantial improvement of the corrosion resistance can be attributed to the combination of the inertness of the Cr layer, and of the densely packed homogeneous nc structure of the nc coatings containing Si and/or C in comparison to columnar crystalline TiN coatings.

Amorphous hydrogenated silicon-carbide (a-SiC:H) coatings appear very attractive due to their superior optical and mechanical properties and chemical inertness. In the present work a-SiC:H coatings were prepared by PECVD on stainless steel 301 (SS301) and Ti–6Al–4V (TiAlV) substrates at a temperature of 300 °C, using different SiH4/CH4 precursor ratios. We systematically studied such mechanical properties as hardness, reduced Young's modulus and elastic recovery using depth-sensing indentation, their tribological characteristics such as coefficient of friction and wear coefficient using the pin-on-disc method, as well as their corrosion and tribo-corrosion behaviors. a-SiC:H films (∼ 3 μm thick) prepared on SS301 and TiAlV at optimal deposition conditions exhibited a hardness of 23.5 GPa, reduced Young's modulus of 160 GPa, and elastic rebound of 73%. They showed a friction coefficient of ∼ 0.35, and a wear rate of 10 × 10−6 mm3/Nm. These values are low compared to ∼ 0.85 and ∼ 0.5, 240 × 10−6 mm3/Nm and 700 × 10−6 mm3/Nm for SS301 and TiAlV, respectively. The films exhibited a very high corrosion and tribo-corrosion resistance on both metallic substrates. The coating behavior is correlated with the microstructure and composition, determined by complementary characterization techniques including ERD, FTIR and Raman analyses.

The use of hard and superhard nanocomposite (nc) coatings with tailored functional properties is limited when applied to low alloy steel substrates due to their low load carrying capacity. Specifically in this work, in order to enhance the performance of martensitic SS410 substrates, we applied a duplex process which consisted of surface nitriding by radio-frequency plasma followed by the deposition of single layer (TiN, nc-TiN/a-SiNx or nc-TiCN/a-SiCN) or multilayer (TiN/nc-TiN/a-SiNx, TiN/nc-TiCN/a-SiCN) coating systems prepared by plasma enhanced chemical vapor deposition (PECVD). We show that plasma nitriding gives rise to a diffusion layer at the surface due to diffusion of nitrogen and formation of the α-Fe and e-Fe2N phases, respectively, leading to a surface hardness, H, of 11.7 GPa, compared to H = 5 GPa for the untreated steel. Among the TiN, nc-TiN/a-SiNx and nc-TiCN/a-SiCN coatings, the latter one possesses the highest H value of 42 GPa and the highest H3/Er2 ratio of 0.83 GPa. Particularly, the TiN/nc-TiCN/a-SiCN multilayer coating system exhibits superior tribological properties compared to single layer TiN and multilayer TiN/nc-TiN/a-SiNx coatings: this includes excellent adhesion, low friction (Cf = 0.17) and low wear rate (K = 1.6 × 10− 7 mm3/N m). The latter one represents an improvement by a factor of 600 compared to the bare SS410 substrate. The significance of the relationship between the H/E and H3/Er2 ratios and the tribological performance of the nano-composite coatings is discussed.

Influence of the deposition parameters and the substrate bias voltage on the optical, compositional and the surface properties of DC magnetron-sputtered silicon nitride thin films are studied. Silicon nitride thin films are deposited on silicon (100) and quartz substrates at different partial pressures of nitrogen and discharge currents. The variation in the refractive index and the optical band gap of these films is studied. Compositional variation has been studied using Rutherford backscattering spectroscopy (RBS). Silicon nitride thin films deposited at $3 \times 10^-^2$ Pa partial pressure of nitrogen with $2.5 mA/cm^2$ cathode current density showed an optical band gap of 4.3 eV and refractive index of 2.04 (at 650 nm). Nitrogen to silicon ratio in the film is 1.31, and the roughness of the films is 2.3 nm. Substrate bias during deposition helped in changing the optical properties of the films. Substrate bias of -60V resulted in films having near stoichiometry with N/Si ratio 1.32, and the optical band gap, refractive index, and the roughness are 4.8 eV, 1.92 and 0.78 nm, respectively.

The effect of substrate orientation and ion bombardment during the growth on the structure and properties of TiN films deposited by reactive unbalanced magnetron sputtering has been reported. Films deposited at a nitrogen partial pressure of 5×10–5 mbar and a current density of 2.50 mA cm–2 were golden yellow in color, characteristic of stoichiometric TiN. The effect of Si(100) and Si(111) substrates on the TiN film along with the substrate bias has been investigated. With an increase in the substrate bias on Si(111) substrate, TiN(111) is the most preferred orientation. On a Si(100) substrate with an increase in the substrate bias, TiN(220) orientation has been observed. The influence of the substrate on the growth of TiN films has been explained in terms of surface energy. The variation of grain size, resistivity, and the internal stress of TiN films as the function of substrate bias have also been investigated.

Fluorination of polymer surfaces has technological applications in various fields such as microelectronics, biomaterials, textile, packing, etc. In this study PMMA surfaces were fluorinated using DC glow discharge plasma. Tetrafluoroethane was used as the fluorinating agent. On the fluorinated PMMA surface, static water contact angle,surface energy, optical transmittance (UV–vis), XPS and AFM analyses were carried out. After the fluorination PMMA surface becomes hydrophobic with water contact angle of $107^o$ without losing optical transparency. Surface energy of fluorine plasma-treated PMMA decreased from 35 $mJ/cm^2$ to 21.2 $mJ/cm^2$. RMS roughness of the fluorinated surface was 4.01 nm and XPS studies revealed the formation of C–$CF_x$ and $CF_3$ groups on the PMMA surface.

Polystyrene (PS) and polyethylene (PE) samples were treated with argon and oxygen plasmas. Microwave electron cyclotron resonance (ECR) was used to generate the argon and oxygen plasmas and these plasmas were used to modify the surface of the polymers. The samples were processed at different microwave powers and treatment time and the surface modification of the polymer was evaluated by measuring the water contact angle of the samples before and after the modification.Decrease in the contact angle was observed with the increase in the microwave power for both polystyrene and polyethylene. Plasma parameters were assessed using Langmuir probe measurements. Fourier transform infrared spectroscopy showed the evidence for the induction of oxygen-based functional groups in both polyethylene and polystyrenewhen treated with the oxygen plasma. Argon treatment of the polymers showed improvement in the wettability which is attributed to the process called as CASING, on the other hand the oxygen plasma treatment of the polymers showed surface functionalization. Correlation between the plasma parameters and the surface modification of the polymer is also discussed.

Polystyrene cell-culture substrates were treated with argon glow discharge to make their surfaces hydrophilic. The process was novel in that it used a microwave electron cyclotron resonance (ECR) source for polymer surface modification. The substrates were processed at different microwave powers and time periods, and the surface modification was assessed with by measurement of the water contact angle. A decrease in contact angle was observed with increasing microwave power and processing time. Beyond a certain limit of power and duration of exposure, however, surface deterioration occurred. The optimum conditions for making the surfaces hydrophilic without deterioration of the samples were identified. The plasma parameters were assessed by Langmuir probe measurement. Fourier transform infrared spectroscopy with attenuated total reflectance showed evidence for the induction of hydrophilicity on the surface. The surface micromorphology was examined with scanning electron microscopy. The results prove that the ECR glow discharge was an efficient method for enhancing the wettability of the polymer surfaces.