Synthesis Of Diamond-like Carbon Films Research Articles

Boron doping of diamond-like carbon films by pulsed laser deposition technique for photovoltaic application

Diamond-like carbon (DLC) films were deposited by pulsed laser deposition technique using a glassy carbon disc as carbon source material. Boron doping in DLC films was carried out by ablating boron disc sequentially during the synthesis of DLC films. Field emission scanning electron microscopy, X-ray photoelectron spectroscopy (XPS) and Raman measurements were utilized to characterize the films. Hot-probe study indicated the films to be p-type. Core level XPS spectra of B1s appeared at ∼ 189.5 eV and indicated that boron atoms are in form of B-C network connect. Raman studies indicated a dilatation of host lattice with the incorporation of boron in DLC matrix favouring graphitization. Band gap of the thin films decreased from ∼2.0 eV (pure DLC) to ∼1.76 eV with increased incorporation of boron. A photovoltaic cell structure (glass/indium tin oxide)/B:DLC/ZnO/Ag) conceived here, indicated an open circuit voltage ∼110 mV, short circuit current density ∼7.5 mA/cm2 with a fill factor ∼0.3, and a low conversion efficiency (η) ∼ 0.23%.

Synthesis of diamond-like carbon films by electro-deposition technique for solar cell applications

High transparent diamond-like carbon (DLC) films were deposited on ITO and silicon substrates by electro-deposition technique using a mixture of methanol and ethanol as electrolyte. The effect of varying of ethanol and methanol volume ratios on optical and structural properties of electrodeposited DLC films was investigated. The increase of methanol volume ratio resulted to an increase in the SP3 content. The optical band gap of the DLC films was found to be in the range of (1.75–2.15) eV. The refractive index of films ranged from 1.19 to 1.39 at the wavelength of 600 nm. The experimental data showed that the best DLC film has an average reflectance less than 4.5 % in the visible region. The efficiency of the silicon solar cells increased from 4.5 to 5.88 % after depositing a 70 nm thick, single antireflection DLC film. The open circuit voltage Voc, short circuit current density Jsc and spectral responsivity of solar cells were investigated as function of DLC film thickness.

Influences of Pulse Frequency on Structure and Mechanical Properties of DLC Films Synthesized by Pulsed Cathodic Arc Evaporation

Diamond-like carbon (DLC) films were prepared on the Si (100) substrates by pulsed cathodic arc plasma. The influences of given pulse frequency on the microstructure, morphology, mechanical and optical properties of DLC films were investigated by Raman spectroscopy, atomic force microscopy, Knoop sclerometer, X-ray double-crystal surface profilometer. The results showed that the variation of pulse frequency could significantly change the microstructure of DLC films, including the size and ordering of sp2carbon clusters and movement or diffusion of carbon atoms. The increasing of pulse frequency led to the variation of the relative fraction of Csp3/Csp2. The hardness and internal stress of the DLC films were affected accordingly. The results might contribute to the synthesis of DLC films with excellent structure and properties by cathodic arc evaporation.

Synthesis of Diamond-Like Carbon Films on Planar and Non-Planar Geometries by the Atmospheric Pressure Plasma Chemical Vapor Deposition Method

Synthesis of Diamond-Like Carbon Films on Planar and Non-Planar Geometries by the Atmospheric Pressure Plasma Chemical Vapor Deposition Method

Synthesis of Diamond-Like Carbon Films on Planar and Non-Planar Geometries by the Atmospheric Pressure Plasma Chemical Vapor Deposition Method

Diamond-like carbon (DLC) films were synthesized by the dielectric barrier discharge-based plasma deposition at atmospheric pressure and their hardness and gas barrier properties were measured. A decrease in size of grains and heating substrate temperature improved nano-hardness up to 3.3 GPa. The gas barrier properties of DLC-coated poly(ethylene terephthalate) (PET) sheets were obtained by 3–5 times of non-coated PET with approximately 0.5 µm in film thickness. The high-gas-barrier DLC films deposited on PET sheets are expected to wrap elevated bridge of the super express and prevent them from neutralization of concrete. We also deposited DLC films inside PET bottles by the microwave surface-wave plasma chemical vapor deposition (CVD) method at near-atmospheric pressure. Under atmospheric pressure, the films were coated uniformly inside the PET bottles, but did not show high gas barrier properties. In this paper, we summarize recent progress of DLC films synthesized at atmospheric pressure with the aimed of food packaging and concrete pillar.

Synthesis of Diamond-Like Carbon Film on Copper and Titanium Interlayer by Vacuum Cathode Arc Evaporation

Using direct-current (DC) and pulsed double-excitation cathode arc plasma technique, diamond-like carbon (DLC) bilayers with nano-scaled interlayer of Cu and Ti were synthesized on silicon substrate. The effect of interlayer on the structure, morphology and mechanical properties of bilayer films were investigated. The change in bilayers structure occurred during interlayer introduction and greatly affected the hardness and internal stress of bilayers. Interlayer nature changed the microstructure of bilayers that in the thickness and element content of diffusion layer. Ti/DLC bilayer exhibited a similarly morphological character to DLC monolayer, whereas Cu interlayer in DLC films leaded to a formation of nanostructured surface and lower root mean square roughness due to the absence of Cu-C bond.

Synthesis of diamond-like carbon films on Si substrates by photoemission-assisted plasma-enhanced chemical vapor deposition

Diamond-like carbon (DLC) films grown by photoemission-assisted plasma-enhanced chemical vapor deposition (PA-PECVD) have attracted attention as a gate insulator for graphene-channel field effect transistors (GFETs). In this study, the possibility of using PA-PECVD to grow insulating DLC films for GFETs is explored by focusing on the growth rate and uniformity of DLC films on Si substrates. Initially, the DLC films were formed at a constant rate but the growth rate decreased rapidly when the thickness reached approximately 400nm. This is because of a decrease in photoelectron emissions from the Si substrates as they are covered by DLC films which absorb UV photons. However, the DLC films formed uniformly at thicknesses less than 16%. This result indicates that PA-PECVD is a promising method for growing DLC films as the gate dielectric layer of GFETs.

116 大気圧下でのDLC膜合成とその機械的特性評価(コーティング・溶射・薄膜プロセス(1),ものづくりにおける基礎研究と先端技術の融合)

116 大気圧下でのDLC膜合成とその機械的特性評価(コーティング・溶射・薄膜プロセス(1),ものづくりにおける基礎研究と先端技術の融合)

Growth and properties of the ion beam deposited SiO x containing DLC films

In the present study SiO x containing diamond-like carbon (DLC) films were synthesized by the closed drift ion source from hexamethyldisiloxane vapor. Kinetics of the growth of DLC films was investigated using optical emission spectroscopy (OES). Structure, chemical composition, electrical and optical properties of the synthesized films were studied. The effects of ion beam energy were investigated. The main atomic hydrogen Balmer series lines and the intense broad CH group related peak were detected in the OES spectra registered in-situ during SiO x containing diamond-like carbon film synthesis. The intensity ratio of H-β/CH peaks increased with the increase of applied ion beam energy. It was explained by activation of the dissociation of the hexamethyldisiloxane molecules. Changes of the structure of the diamond-like carbon films were observed for the films deposited under intense dissociation conditions.

탄소비율에 따른 Diamond-like Carbon Film의 광학적 및 기계적 특성

Optical and mechanical properties of diamond-like carbon (DLC) films synthesized by RF plasma enhanced chemical vapor deposition were investigated as a function the C/H ratio in gas mixture. The C/H ratio was varied from 6 to 10 %, adjusting the amount of and as the source gas. The optical and mechanical properties of DLC films were characterized by UV spectrometer, Ellipsometer and Nano-indenter. The change of the C/H ratio during synthesis of DLC films had many effects on the growth rate, transmittance, refractive index and hardness. The growth rate of the films increased exponentially with the increase in C/H ratio. The hardness of the films showed the tendency to improve with increasing C/H ratio, whereas the transmittance decreased. The refractive index was varied from 2.03 to 2.17, and these refractive indexes close to 2.0 indicates that it can be applied to Si-based solar cell.

Synthesis of DLC films with different sp2/sp3 ratios and their hydrophobic behaviour

Diamond-like carbon (DLC) films were deposited on glass substrate by sputtering of a vitreous carbon target in Ar + H2 plasma. The sp2/sp3 content in the films depended on the relative amount of hydrogen in the Ar + H2 plasma. The films were characterized by Fourier transformed infrared studies, Raman studies, scanning electron microscopy, atomic force microscopy and optical measurements. Hydrophobicity in these films was studied by measuring the contact angles of the water droplets and it was found that the films were extremely hydrophobic. The results are interpreted in terms of hybridization of carbon in these DLC films.

Synthesis of Diamond-like Carbon Films by Nanopulse Plasma Chemical Vapor Deposition in Open Air

Deposition of Diamond-Like Carbon (DLC) films at atmospheric pressure is one of promising techniques to achieve in-process coatings regardless work sizes. This research aims at synthesis of DLC films under atmospheric pressure by nanopulse Chemical Vapor Deposition (CVD) method using unique power source system that consists of a static induction (SI) thyristor and an Inductive Energy Storage (IES). In this report, we realized synthesis of DLC films in open air (101 kPa). Deposition rate was as high as 0.4μm/min, and the hardness of the film was 20.6 GPa. From Raman spectroscopic analysis, quality of film significantly depends on input power and deposition time.

Synthesis of DLC films by PECVD combined with hollow cathode sputtering

The mechanical and electrical properties of aluminium-doped diamond-like carbon (DLC) thin films obtained with a hybrid method combining hollow magnetron discharge sputtering and plasma-enhanced chemical vapour deposition (PECVD) are reported. The ratio between the mass flows of methane reactive gas and argon inert gas was found to have a big influence on the properties of doped DLC films. For low mass flow of methane gas the cathode surface was kept in a metallic state. By increasing methane mass flow the cathode surface became to be covered with DLC and the behaviour of the discharge changed, influencing the properties of deposited films. The lowest resistivity (10 −4 Ω cm) of thin films was obtained in the metallic state of the cathode but without DLC character, as indicated by Raman measurements. The resistivity increased in the intermediate mode (0.01 Ω cm) and attained higher value (1 Ω cm) in the poisoned state of the cathode. These films presented DLC character, with D and G bands, as revealed by Raman measurements.

Low-Temperature Synthesis of Diamond-like Carbon Films on Steel Substrates by Electron-Cyclotron-Resonance Plasma-Enhanced Chemical Vapor Deposition

Using microwave electron-cyclotron-resonance plasma-enhanced chemical vapor deposition, diamond-like carbon films were directly grown at low temperatures (lessthan equal to400°C) on Fe-based alloy substrates without diamond seeding or use of a template layer. A single, broad line in the Raman spectra was observed in the region of 1328-1335 cm-1 for films grown in gas mixtures with a ratio of CH4:H2 greaterthan equal to 2%. In contrast, disordered carbon and graphite phases appeared in the spectra for film grown with a concentration of 20% CH4 in hydrogen. Diamond nucleation with an amorphous carbon layer was observed in the initial growth stage, while many diamond particles with irregular morphological features were observed on the surface of thicker films. These growth features are a consequence of the catalytic nature of the Fe-based substrate.

Synthesis of DLC films by electrodeposition technique using formic acid as electrolyte

Diamond-like carbon (DLC) films were deposited by electrodeposition technique using formic acid and water as electrolyte. Films were deposited onto SnO 2-coated glass substrates at different ratios of acid and water. Effect of applied voltage during electrolysis on the film properties was also studied. The films are compact with quite smooth surface and showed enhanced field emission properties when subjected to hydrogen plasma treatment. Raman spectra showed two distinct broad characteristic peaks at 1360 and 1600 cm −1. Band gap and refractive index of the films varied between 2.0–2.5 eV and 1.2–1.8, respectively. FTIR spectra showed the characteristic peaks related both to CH 3 and CH 2 vibration modes. Field emission studies indicated the critical voltage and current ∼16 V/μm and 5.44 mA/m 2, respectively.

Synthesis of DLC Films by Electrolysis of Dimethyl Sulfoxide

Amorphous diamond-like carbon (DLC) films were deposited on a silicon substrate by electrolysis of analytically pure dimethyl sulfoxide at relatively low voltage (150 V). Atomic force microscopy was used to investigate the surface morphology of the sample and indicated that the film was composed of small grains ∼100 nm in size. The composition and structure of the films were characterized by X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and Raman spectroscopy. Results showed that the deposits were hydrogenated DLC films containing considerable sp 3 carbon, which could be transformed to sp 2 carbon through an annealing treatment.

Synthesis of diamond-like carbon film by novel electrodeposition route

Diamond-like carbon films were deposited by electrodeposition technique onto SnO 2-coated glass substrates by using a mixture of acetic acid and water as electrolyte. The films are compact with quite smooth surface. Raman spectra showed two distinct broad characteristic peaks at ∼1350 and ∼1600 cm −1. Shift in the peak position was found to depend on the microstructure of the films. XRD spectrum of the films indicated strong peaks for (1 1 1) and (2 2 0) planes located at 2θ=43.9° and 75.2°, respectively. Band gap and refractive index of the films deposited at different voltage varied between 2.87–3.08 and 1.55–1.61 eV, respectively.

Dynamic MC simulation of DLC films synthesis by PBII

Dynamic Monte Carlo simulations have been applied to the synthesis of diamond-like carbon films by plasma-based ion implantation (PBII). The direct chemical incorporation of the radicals, like CH 3 reacting with a diamond surface, is too low for the deposition of DLC films, so that the other reaction mechanisms should be responsible. We assumed a surface reaction layer consisted of several radical layers, in which radicals are dissociated by the collisions with energetic ions and some H and C atoms are released out and some H and C atoms are stitched into the subsurface and the stitched C atoms are assumed to form the sp 3 states. In the subsurface, it was assumed that sp 3 states atoms are released to the sp 2 state and H atoms are released out of the surface as a results of collision cascades induced by the energetic ions. The following was obtained by the simulation: the C atom stitching probability, which related with sp 3 state formation, has a maximum of near 500 eV independent of the dissociation energy of radicals, number of monolayers in the surface reaction layer, or ion/radical arrival ratio. It agrees with the experimental result. The stitching probability increases with the decrease of the dissociation energy and the increase of number of monolayers in the surface reaction layer and ion/radical ratio. The H concentration shows a maximum of near 300 eV. It also agrees with the experimental result.

Dynamic MC simulations of diamond-like carbon film synthesis by plasma-based ion implantation

By plasma-based ion implantation (PBII) such as low-energy ion beam implantation in plasma, ion beam assisted deposition, and plasma immersed ion implantation, a diamond-like carbon (DLC) film is synthesized. The structure of the DLC film can be characterized by the hydrogen concentration and the relative fractions of sp 2- and sp 3-bonded carbon. The energy of the impinging ion plays a crucial role for the film structure and thereby the mechanical, electrical and optical properties of the film. Dynamic Monte Carlo simulations with the binary collision approximation have been applied to the synthesis of DLC films by PBII. It was assumed that energetic CH 3 + ions and CH 3 radicals are incident on the surface alternately. The incident molecular ions dissociated into its individual atoms when colliding with the surface. The radicals adsorbed on the surface are dissociated by the binary collisions with the impinged atoms and a part of hydrogen atoms are released from the surface. It is assumed that only the atoms receiving enough energy to overcome the surface barrier enter the solid. Release of the displaced hydrogen atoms after the subsequent collision cascade is also assumed. The relative fraction of carbon atoms in the sp 2 and sp 3 state were estimated by setting different displacement threshold energy for each state. Effects of the ion/neutral arrival ratio and the ion energy on the deposition rate and on the depth profile of the hydrogen content and the sp 3/sp 2 ratio in the deposited film are presented.

Synthesis of diamondlike carbon films with superlow friction and wear properties

In this study, we introduce a new diamondlike carbon (DLC) film providing a friction coefficient of 0.001 and wear rates of 10−9–10−10 mm3/N m in inert-gas environments (e.g., dry nitrogen and argon). The film was grown on steel and sapphire substrates in a plasma enhanced chemical vapor deposition system that uses a hydrogen-rich plasma. Employing a combination of surface and structure analytical techniques, we explored the structural chemistry of the resultant DLC films and correlated these findings with the friction and wear mechanisms of the films. The results of tribological tests under a 10 N load (creating initial peak Hertz pressures of 1 and 2.2 GPa on steel and sapphire test pairs, respectively) and at 0.2 to 0.5 m/s sliding velocities indicated that a close correlation exists between the friction and wear coefficients of DLC films and the source gas chemistry. Specifically, films grown in source gases with higher hydrogen-to-carbon ratios had the lowest friction coefficients and the highest wear resistance. The lowest friction coefficient (0.001) was achieved with a film on sapphire substrates produced in a gas discharge plasma consisting of 25% methane and 75% hydrogen.