Papers by Keyword: Diamond-Like Carbon (DLC)

Abstract: Undoped diamond like carbon thin films have been grown by DC - PECVD system. The synthesis of the DLC films was carried out in the presence of gas of (CH₄ + H₂ + Ar) in a custom made reactor. The substrate temperature was initiated from the range of 300 °C to 600 °C under an optimum pressurized medium. The AFM image reveals that the optimization of DLC films growth at the substrate temperature 400 °C has a significant surface roughness and average grain size which is compatible to the result of film thickness measurement. The sample J400 shows an excellent nonlinear rectifying diode-like characteristic across the small potential difference.

Abstract: Diamond-like carbon (DLC) films were synthesized on a p-type silicon wafer using radio-frequency plasma composed of a mixture of Ar and C₂H₂ (ratio of 7 to 28). NH₃ plasma treatment of as-grown DLC substrate was carried out to generate surface-terminal amino groups while oxidation of as-grown DLC was performed in O₂ plasma. X-ray photoelectron spectroscopy (XPS) was used to characterize the different surface functions formed on DLC surfaces. Water contact angle measurements indicate different wetbility of modified surfaces. The cell (Mouse MC₃T₃-E₁ pre-osteoblasts) morphology and proliferation were monitored to evaluate the biocompatibility of the modified DLC surfaces. A cell count kit-8 (CCK-8 Beyotime) was employed to determine quantitatively the viable pre-osteoblasts. The cell viability assay shows that osteoblast proliferation are improved on NH₃ and O₂ plasma-treated DLC surface after culturing for 1day, 2days and 3 days. The cell-surface interactions are studied by fluorescence microscopy. There are more osteoblasts as well as better spreading on the aminated and oxidized surfaces after culturing for 3 days. In summary, compared to the as-grown sample, the modified DLC shows better biocompatibility.

Abstract: This paper mainly focuses in the use of an atomic force microscope, research about the nanooxidation technique of conductive diamond-like carbon thin film in the atmospheric environment. The hardness, high wear resistance and chemical stability of diamond-like carbon thin film is high, and coefficient of friction is low, it is very suitable as a mold material for nanoscale mold. However, tool can only use a diamond cutter to machine the high hardness diamond-like carbon by traditional hard machining method, and tool life is not long. To overcome this drawback, the paper proposed an atomic force microscope (AFM) as a platform, a conductive AFM probe for tool under atmospheric conditions, and imposed nanooxidation technique on conductive diamond-like carbon thin film using electroluminescent etching to carry out nanofabrication processing. During the nanofabrication process, by changing the various processing parameters, such as applied voltage, repeated nanooxidation times and probe speed, etc., in order to understand the effect of processing parameters. The experimental results show, the nanooxidation technique can be carried out nanofabrication on conductive diamond-like carbon thin film successfully. And found that applied voltage, repeated nanooxidation times and probe speed all for the groove depth on the conductive diamond-like carbon thin films have significant influence. Additionally, this study successfully created a nanopattern. Therefore, the adequate machinability of DLC coating was achieved successfully in this study, indicating a promising application in the fabrication of nanopatterns on a nanoscale.

Abstract: Undoped diamond like thin films have been prepared by using Direct Current - Plasma Enhanced Chemical Vapour Deposition system. A potentially diamond thin films was fabricated in the presence of gas mixture which accordance to the ratio CH₄ (1%) + H₂ (39%) + Ar (60%). The substrate temperature was controlled and adjusted from 300 °C to 500 °C in a vacuum chamber with the optimum pressure of 4 X 10^-1 Torr. The films were characterized by X ray diffraction microscopy (XRD), Photoluminescene spectroscopy (PL) and Fourier Transform Infrared (FTIR) spectroscopy. It shows that, XRD pattern shown that the film was formed in the amorphous phase with a high fraction of sp³ hybridization. Luminescene band shows the peak position at (3.16 eV and 2.94 eV), (3.16 eV and 2.95 eV), (3.17 eV and 2.93 eV) and (3.26 eV) for the films deposited at 300, 350, 400 and 500 °C, respectively. The structural configuration of film obtained which corresponding to the sp³ hybridization of C H bonding gives a most significant result at approximately 760 cm^-1 region was presented.

Abstract: Diamond-like carbon (DLC) films and nitrogen doped DLC (NDLC) were deposited on glass slide and H13 steel by plasma-enhanced chemical vapor deposition using a commercial RF 13.56 MHz (RF-PECVD). The films have been prepared from CH₄ for DLC and CH₄+N₂ mixtures for NDLC. The deposition process was at 300°C under argon atmosphere for 120 min. Bonding energy and diamond like carbon characteristic of DLC and NDLC films have been characterized by Fourier Transform Infrared Spectroscopy (FTIR) and Raman spectroscopy. Thermalgravimetric Analyzer (TGA) was used to evaluate the thermal stability of the films which were scrapped off from a glass slide substrate. The mechanical properties was characterized, such as hardness by nanoindentation technique, scratch test by Rockwell diamond tip in progressive mode and friction coefficient have been measured in ambient air using a ball-on-disk tribometer.

Abstract: Analysis of mechanical properties of diamond-like carbon (DLC) films based on experimental designs was reported to optimize characterize by a magnetron sputtering. An orthogonal array experiment was introduced and the effects of deposited parameters on the films were systematically explored. The films were analyzed by scanning electron microscopy (SEM). Friction and wear tests were carried out using a pin-on-disk tribometer. In this study, the two stages such as adhesive and abrasive wears for tribological properties are clearly visible among L18 tests, where at the higher wear volume losses exist an abrasive wear while the less wear volume losses appear an adhesive wear. A slightly worn surface with a glassy carbon phase appeared and a lower wear volume loss became visible in the DLC films. Through the optimal design, the experimental results demonstrate the tribological properties on DLC multilayer films are increased by a magnetron sputtering, thereby justifying the reliability and feasibility of the approach.

Abstract: Composite SiN_x/DLC films were deposited on silicon substrate by co-deposition system. The carbon plasma was generated by filtered cathodic arc source, simultaneously incorporated with silicon nitride from RF magnetron sputtering. The silicon nitride sputtering rate was maintained by fixed RF power at 100W while the arc current of FCA was varied from 20 to 80A.The SiN_x/DLC film composition and optical properties were investigated by X-ray photoelectron spectroscopy and spectroscopic ellipsometry respectively. The results revealed that the atomic concentration of carbon increased while those of silicon and nitrogen decreased with increasing arc current. The oxidation was found on the film surface and related to the atomic concentration of silicon. The optical properties can be changed as a function of carbon concentration by setting different arc current. In this work, the volume percentage of carbon obtained from spectroscopic ellipsometry using Bruggeman EMA model showed good numerical correlation with the atomic percentage of carbon from XPS analysis with the range spanning across 75-95 at. %.

Abstract: The correlation of Diamond-Like Carbon (DLC) bonding structure versus film corrosion protective capability against Hydrofluoric (HF) acid exposure was made. Raman analysis of DLC films that were subjected to repeated thermal cycle heating showed that were more clustering in sp² sites upon exposure to high temperature and increasing time. When these films were subsequently exposed to HF acid, there was also corresponding increase in the amount of pitting corrosion features. The increase in sp² clustering size is seen as a weak point in the overall DLC structure which subsequently allowed the acid to penetrate the film structure.

Abstract: Diamond-like carbon (DLC) films were deposited on magnetic recording head by Filtered Cathodic Arc (FCA) technique and a-Si base material was ion beam deposited as seed layer. To investigate the thermal stability of stack film, repeated cycle thermal heating at 200 °C was employed. Raman spectroscopy and nanoindenter (Hysitron) were performed to understand film structure and mechanical property as a function of thermal heating conditions. The roles of heating in material composition and wear behavior of DLC films are discussed. The Raman spectra revealed that G position, FWHM of G peak and Id/Ig change as with increasing heating cycle which agreed well with wear depth measured. With these results suggesting DLC film degraded with repeated heating at 200 °C.

Abstract: Ag nanoparticles (NPs) have prominent local surface plasma resonance effect (LSPR), and Ag NPs exhibit sharpest and strongest bands among all metals. Diamond-like carbon (DLC) film have good biological compatibility and also have high transmissibility in the visible and near-infrared region. A new LSPR interface between Ag NPs and ultra-thin DLC film was formed by Plasma Enhanced Chemical Vapor Deposition. The morphologies and properties of the Ag NPs coated with DLC film were studied with SEM and AFM. The results indicated that the thickness of DLC film increased with the deposition time. LSPR peak became sharper after depositing for 1 or 2 min. DLC film was prior to nucleate on the surface of Ag NPs, and it has high content of sp² bonds near the interface. The sensitivity of new LSPR interface deposited for 20s was about the half of the sensitivity of bare Ag NPs and the sensitivity significantly decreased with deposition time. This result is helpful to understand the behavior of the new LSPR interface and to improve its sensitivity.