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  • American Vacuum Society  (4)
  • Physics  (4)
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  • American Vacuum Society  (4)
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  • Physics  (4)
RVK
  • 1
    Online Resource
    Online Resource
    American Vacuum Society ; 2003
    In:  Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena Vol. 21, No. 1 ( 2003-01-01), p. 623-626
    In: Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena, American Vacuum Society, Vol. 21, No. 1 ( 2003-01-01), p. 623-626
    Abstract: We examined how the addition of different metal buffer layers between the Ni/Fe-alloy-catalyst layer and the silicon substrate affected the growth of nanostructured carbon films; Cr, Ti, Ta, and W were tested as buffer layers. Even when the sputter-deposition of catalytic-metal layers and the hot filament chemical vapor deposition of carbon films were carried out under the identical conditions, different buffer layers resulted in substantially different carbon-film growth. More specifically, carbon-nanoparticle films were produced with the Cr and the W buffer layers, and carbon-nanotube films were produced with the Ti and the Ta buffer layers. X-ray diffraction (XRD) showed a significant and systematic difference between the carbon-nanoparticle and carbon-nanotube films. In the case of the carbon-nanoparticle films deposited with either the Cr or the W buffer layer, the peaks corresponding to the catalytic metal, the carbide phases of the catalytic metal, and the carbide phases of the respective buffer metal were observed. However, in the case of the carbon-nanotube films deposited with either the Ti or the Ta buffer layer, the peaks corresponding to the carbide phases of the catalytic metal and the silicide phases of the respective buffer metal were observed. Moreover, scanning electron microscopy (SEM) images of the cross sections of the films showed the difference in the interface structure and its deposition-time-dependent change. Based on the XRD and cross-section SEM observations, we proposed a model that could account for the growth of different nanostructured carbon films on the different sets of buffer layers.
    Type of Medium: Online Resource
    ISSN: 1071-1023 , 1520-8567
    RVK:
    Language: English
    Publisher: American Vacuum Society
    Publication Date: 2003
    detail.hit.zdb_id: 3117331-7
    detail.hit.zdb_id: 3117333-0
    detail.hit.zdb_id: 1475429-0
    Location Call Number Limitation Availability
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  • 2
    Online Resource
    Online Resource
    American Vacuum Society ; 2003
    In:  Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena Vol. 21, No. 1 ( 2003-01-01), p. 576-580
    In: Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena, American Vacuum Society, Vol. 21, No. 1 ( 2003-01-01), p. 576-580
    Abstract: We investigated the structural variation and the concomitant change in the emission characteristics of hot-filament chemical-vapor-deposition-grown nanostructured carbon films induced by the addition of ammonia to source gases. At low ammonia concentrations the film morphology was dominated by carbon nanoparticles encapsulating metal and/or carbide cores. As the ammonia concentration was increased nanotube density increased, and in the medium ammonia-concentration range nanotubes dominated the film morphology. However, at 80% of ammonia concentration the number of nanotubes decreased substantially and nanoparticles became the dominant species again. The diameter, length, and shape of nanotubes also showed systematic ammonia-concentration- dependent variations, while the nanoparticle size did not change significantly. Another important variation was found in the quality of carbon layers constituting the carbon nanoparticles and nanotubes. As more and more ammonia was added to the source gas, large structural deterioration, including the increase of disorder in the atomic bonding and the decrease of graphitic sheet size, was observed. The electron-emission characteristics of these films were as diverse as their morphological and structural variations. At the low ammonia-concentration range, the emission was degraded as the ammonia concentration was increased. However, when the ammonia concentration was increased up to 40%, the emission was recovered almost back to the best level. At higher ammonia concentrations, substantial emission degradation recurred.
    Type of Medium: Online Resource
    ISSN: 1071-1023 , 1520-8567
    RVK:
    Language: English
    Publisher: American Vacuum Society
    Publication Date: 2003
    detail.hit.zdb_id: 3117331-7
    detail.hit.zdb_id: 3117333-0
    detail.hit.zdb_id: 1475429-0
    Location Call Number Limitation Availability
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  • 3
    Online Resource
    Online Resource
    American Vacuum Society ; 2003
    In:  Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena Vol. 21, No. 1 ( 2003-01-01), p. 562-566
    In: Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena, American Vacuum Society, Vol. 21, No. 1 ( 2003-01-01), p. 562-566
    Abstract: To identify the deposition conditions that can minimize the nanotube density in the nanostructured carbon films without compromising the emission properties, we carried out a systematic investigation of the effect of deposition conditions on the emission properties and the structure of the nanostructured carbon films. Catalyst-layer thickness, methane concentration, deposition time, deposition pressure, and substrate temperature were the main deposition parameters we investigated. Within the parameter range for nanoparticle-dominant growth, substrate temperature and deposition time were the two factors that had the largest effect on the variation of the turn-on field. However, catalyst-layer thickness and methane concentration turned out to be the factors allowing the minimization of nanotube density with rather small concomitant variations of the turn-on field. A 50 h test showed that the emission stability of a nanoparticle film was better than that of a multiwall nanotube film with comparable emission characteristics. The feasibility of triode fabrication was verified by the successful deposition of a nanoparticle-film cathode of about 8 μm diameter using the conventional photolithography process.
    Type of Medium: Online Resource
    ISSN: 1071-1023 , 1520-8567
    RVK:
    Language: English
    Publisher: American Vacuum Society
    Publication Date: 2003
    detail.hit.zdb_id: 3117331-7
    detail.hit.zdb_id: 3117333-0
    detail.hit.zdb_id: 1475429-0
    Location Call Number Limitation Availability
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  • 4
    Online Resource
    Online Resource
    American Vacuum Society ; 1998
    In:  Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena Vol. 16, No. 2 ( 1998-03-01), p. 724-728
    In: Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena, American Vacuum Society, Vol. 16, No. 2 ( 1998-03-01), p. 724-728
    Abstract: We have studied the field emission characteristics of defective diamond films grown by microwave plasma enhanced chemical vapor deposition. X-ray diffraction, Raman spectroscopy, scanning electron microscopy, atomic force microscopy, and the reflectance measurements have revealed the poor crystal quality and/or small grain sizes of the diamond phase and the inclusion of the non-diamond carbon phases in these films. The degrees of the film defectiveness have been found to depend on the methane concentration. Current-versus-voltage measurements have demonstrated that the defective diamond films have good electron emission characteristics, and, moreover, that the emission characteristics depend on the methane concentration. The observed correlation between the degrees of film defectiveness and the emission characteristics strongly suggests the defect-related electron-emission mechanism. In this study, the lower limits of the field emission current densities, estimated by averaging the total measured emission currents over the entire sample areas, of 1 μA/cm2 and 1 mA/cm2 have been measured at electric fields as low as 4.5 and 7.6 V/μm, respectively. We have also examined the reproducibility, the uniformity, and the stability of emission currents.
    Type of Medium: Online Resource
    ISSN: 1071-1023 , 1520-8567
    RVK:
    Language: English
    Publisher: American Vacuum Society
    Publication Date: 1998
    detail.hit.zdb_id: 3117331-7
    detail.hit.zdb_id: 3117333-0
    detail.hit.zdb_id: 1475429-0
    Location Call Number Limitation Availability
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