教師著作

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Browsing 教師著作 by Author "C.-C. Yeh"

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    Catalytic Growth and Characterization of Gallium Nitride Nanowires
    (American Chemical Society, 2001-03-28) Chia-Chun Chen; C.-C. Yeh; C.-H. Chen; M.-Y. Yu; H.-L. Liu; J.-J. Wu; K.-H. Chen; L.-C. Chen; J.-Y. Peng; Y.-F. Chen
    The preparation of high-purity and -quality gallium nitride nanowires is accomplished by a catalytic growth using gallium and ammonium. A series of catalysts and different reaction parameters were applied to systematically optimize and control the vapor−liquid−solid (VLS) growth of the nanowires. The resulting nanowires show predominantly wurtzite phase; they were up to several micrometers in length, typically with diameters of 10−50 nm. A minimum nanowire diameter of 6 nm has been achieved. Temperature dependence of photoluminescence spectra of the nanowires revealed that the emission mainly comes from wurtzite GaN with little contribution from the cubic phase. Moreover, the thermal quenching of photoluminescence was much reduced in the GaN nanowires. The Raman spectra showed five first-order phonon modes. The frequencies of these peaks were close to those of the bulk GaN, but the modes were significantly broadened, which is indicative of the phonon confinement effects associated with the nanoscale dimensions of the system. Additional Raman modes, not observed in the bulk GaN, were found in the nanowires. The field emission study showing notable emission current with low turn-on field suggests potential of the GaN nanowires in field emission applications. This work opens a wide route toward detailed studies of the fundamental properties and potential applications of semiconductor nanowires.
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    Infrared and Raman-Scattering Studies in Single-Crystalline GaN Nanowires
    (Elsevier, 2001-09-14) H.-L. Liu; Chia-Chun Chen; C.-T. Chia; C.-C. Yeh; C.-H. Chen; M.-Y. Yu; S. Keller; S. P. DenBaars
    Infrared and Raman-scattering studies of high-purity and -quality GaN nanowires are presented. The nanosize dependences of the peak shift and the broadening of the four first-order Raman modes agree with those calculated on the basis of the phonon confinement model. Additionally, the appearance of one Raman mode at ∼View the MathML source is attributed to zone-boundary phonon activated by surface disorders and finite-size effects. Moreover, the Raman-scattering intensities of certain phonons show a different resonantly enhanced behavior, which can be used to verify the information on the electronic structures and the electron–phonon interaction in GaN nanowires.
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    Preparation and Characterization of Carbon Nanotubes Encapsulated GaN Nanowires
    (Elsevier, 2001-09-10) Chia-Chun Chen; C.-C. Yeh; C.-H. Lang; C.-C. Lee; C.-H. Chen; M.-Y. Yu; H.-L. Liu; L.-C. Chen; Y.-S. Lin; K.-J. Ma; K.-H. Chen
    A novel two-step catalytic reaction is developed to synthesize gallium nitride nanowires encapsulated inside carbon nanotubes (GaN@CNT). The nanowires are prepared from the reaction of gallium metal and ammonium using metals or metal alloys as a catalyst. After the formation of the nanowires, carbon nanotubes are subsequently grown along the nanowires by chemical vapor deposition of methane. The structural and optical properties of pure GaN nanowires and GaN@CNT are characterized using scanning electron microscopy, transmission electron microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy and Raman spectroscopy. The results show that GaN nanowires are indeed encapsulated inside carbon nanotubes. The field emission studies show that the turn-on field of GaN@CNT is higher than that of carbon nanotubes, but substantially lower than that of pure GaN nanowires. This work provides a wide route toward the preparation and applications of new one-dimensional semiconductor nanostructures.
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    Preparation of Fluorescent Silica Nanotubes and their Application in Gene Delivery
    (Wiley-VCH Verlag, 2005-02-01) Chia-Chun Chen; Y.-C. Liu; C.-H. Wu; C.-C. Yeh; M.-T. Su; Y.-C. Wu
    Fluorescent silica nanotubes are synthesized through a sol–gel reaction using an anodic aluminum oxide membrane template. The nanotubes are filled with plasmid DNA encoding green fluorescence protein (GFP), which are incorporated into mammalian cells that subsequently express GFP (see Figure). The results demonstrate a novel application of nanotubes in biomolecule delivery.