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ABSTRACT: Nanocrystalline diamond (NCD) films were produced by microwave plasma-enhanced chemical vapor deposition (MPECVD) using gas
mixtures of Ar, H2, and CH4. The structural properties, electron emission, and electric discharge behaviors of the NCD films varied with H2 flow rates during MPECVD. The turn-on field for electron emission at a pressure of 2.66×10−4Pa increased from 4.2Vμm−1 for the NCD films that were deposited using a H2 flow rate of 10cm3min−1 to 7Vμm−1 for films deposited at a H2 flow rate of 20cm3min−1. The NCD film with a low turn-on field also induced low breakdown voltages in N2. The grain size and roughness of the NCD films may influence both the electron emission and the electric discharge behaviors
of the NCD cathodes.
Journal of Electronic Materials 04/2012; 38(6):750-755. · 1.47 Impact Factor
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ABSTRACT: Vacuum metal deposition (VMD) utilizing sequential Au and Zn depositions has been an effective technique to develop latent fingerprint on plastic surfaces. A simplified vacuum deposition process was conducted to develop fingerprint in this study. While pure ZnO was thermally evaporated in a vacuum system, ZnO could condense on polyethylene terephthalate (PET) surface. Direct deposition of ZnO, without applying Au seeding, yielded normal development of latent fingerprint. The development of aged fingerprint by ZnO deposition was more effective than that by Au/Zn VMD.
Forensic science international 04/2011; 207(1-3):14-8. · 2.10 Impact Factor
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ABSTRACT: Silicon nanostructures were produced by sputter deposition of silicon in mixtures of hydrogen and argon, on the surface of a silicon substrate with dispersed gold islands, at a substrate temperature of 450 degrees C. Continuous Si films were deposited when the hydrogen concentration in the working gas was less than 50%. Silicon nanocone arrays were grown when the hydrogen concentration exceeded 50%. The lateral size of silicon nanocones increased with the deposition time. However, the length of the silicon nanocones saturated as the deposition time was increased. Mechanisms of the growth of Si nanocones by sputter deposition in mixtures of hydrogen and argon were discussed.
Journal of Nanoscience and Nanotechnology 10/2009; 9(10):5927-31. · 1.56 Impact Factor
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Pai-Chun Wei,
Surojit Chattopadhyay,
Fang-Sheng Lin,
Chih-Ming Hsu, Shyankay Jou,
Jr-Tai Chen,
Ping-Jung Huang,
Hsu-Cheng Hsu,
Han-Chang Shih,
Kuei-Hsien Chen,
Li-Chyong Chen
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ABSTRACT: Photoluminescence (PL) behaviour in InN nanocolumns reveal decreasing, increasing and near invariant peak energies (E(PL)) as a function of temperature. Samples, having E(PL)~0.730 eV at 20 K, showed temperature invariance of E(PL). Samples possessing E(PL) on the lower and higher energy side of 0.730 eV demonstrate a normal redshift and anomalous blueshift, respectively, with increasing temperature. This temperature evolution can be effectively explained on the basis of a competition between a conventional red shift from lattice dilation, dominant for low carrier density sample, on one hand, and a blue shift of the electron and hole quasi Fermi-level separation, dominant for high carrier density samples, on the other.
Optics Express 08/2009; 17(14):11690-7. · 3.59 Impact Factor
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ABSTRACT: Recent developments of tip-based nanofabrication (TBN) are reviewed. In TBN, a functionalized cantilevered-tip is the common basic apparatus for performing the tasks of nanofabrication. The nanofabrication applications of three major techniques under the TBN family: atomic force microscopy (AFM), dip-pen nanolithography (DPN), and scanning near-field optical microscopy (SNOM), are studied with the focus on their manipulability over the size, orientation, and position of the nanostructures fabricated. The nanostructures made by these techniques are selectively presented in order to illustrate the versatility and advancement of these tip-based techniques. The information reviewed and illustrated is extrapolated to form the basis for the assessment of the needs and challenges facing the TBN community in the future. A preliminary roadmap over the next seven years is then developed. The prospective approaches and focusing areas for future research and development are also discussed.
Journal of Nanoscience and Nanotechnology 06/2008; 8(5):2167-86. · 1.56 Impact Factor
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ABSTRACT: Nickel nanorods have been produced by annealing a dense composite film. The nanorods of 45-140 nm in lateral dimensions and 230-1400 nm in longitudinal dimensions were obtained by annealing NiO-YSZ composite films in H2 at 800 degrees C for one hour. The axis of the nanorods at the (220) direction was observed. The dense NiO-YSZ composite film was originally created by co-sputtering Ni and Zr-Y-Ce targets in Ar and O2 environment at 350 degrees C. Reduction of NiOx to Ni nuclei takes place on the surface of the film. The low crystallinity of the original composite film is believed to facilitate the NiO to grow into Ni nanorods on the discrete Ni seeds by diffusion.
Journal of Nanoscience and Nanotechnology 02/2008; 8(1):390-2. · 1.56 Impact Factor
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ABSTRACT: Nanocrystalline diamond (NCD) film was deposited on a silicon substrate utilizing microwave plasma-enhanced chemical vapor deposition in a mixed flow of methane, hydrogen and argon. The deposited film had a cauliflower-like morphology, and was composed of NCD, carbon clusters and mixed sp2- and sp3-bonded carbon. Electron field emission (EFE) in vacuum and electrical discharges in Ar, N2 and O2 using the NCD film as the cathode were characterized. The turn-on field for EFE and the geometric enhancement factor for the NCD film were 8.5 V/μm and 668, respectively. The breakdown voltages for Ar, N2 and O2 increased with pressures from 1.33 × 104 Pa to 1.01 × 105 Pa, following the right side of the normal Paschen curve.
Thin Solid Films 518(15):4458-4461. · 1.89 Impact Factor
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ABSTRACT: The electron field emission (EFE) properties of silicon nanostructures (SiNSs) coated with ultra-nanocrystalline diamond (UNCD) were characterized. The SiNS, comprising cauliflower-like grainy structure and nanorods, was generated by reaction of a Si substrate with an Au film at 1000 °C, and used as templates to grow UNCD. The UNCD films were deposited by microwave plasma-enhanced chemical vapour deposition (MPECVD) using methane and argon as reaction gases. The UNCD films can be grown on the SiNS with or without ultrasonication pretreatment with diamond particles. The EFE properties of the SiNS were improved by adding an UNCD film. The turn-on field (E0) decreased from 17.6 V/μm for the SiNS to 15.2 V/μm for the UNCD/SiNS, and the emission current density increased from 0.095 to 3.8 mA/cm2 at an electric field of 40 V/μm. Ultrasonication pretreatments of SiNS with diamond particles varied the structure and EFE properties of the UNCD/SiNS. It is shown that the ultrasonication pretreatment degraded the field emission properties of the UNCD/SiNS in this study.
Vacuum. 84(1):111-114.
