| Summary: | 碩士 === 國立臺灣師範大學 === 物理研究所 === 91 === In this thesis, the microwave plasma enhanced chemical vapor deposition method was used to synthesize carbon nanotubes on the tip of iron needle. The morphology of the carbon nanotubes changed with the gas species and the diameters of the carbon nanotubes increased with the gas pressure in the chamber. The organic iron catalysts precoated on the tip pronouncedly improved the carbon nanotubes grow uniformity. Moreover, carbon nanotubes were synthesized by using graphite powder and diamond powder as the carbon sources.
Optical emission spectra of the microwave enhanced plasma in the synthesizing process were analyzed to optimize the growing process and to investigate the growth mechanism. From the gas species and the corresponding plasma temperature calculated from the spectra, solid-liquid-solid model was proposed to explain the growing mechanism for the carbon nanotubes on the tip of iron needle. The topography image of carbon nanotubes is characterized by scanning tunneling microscopy.
The field emission properties are markedly influenced by heating and laser irradiation. Finally, a prototype electron field emitter was demonstrated, which shows that carbon nanotubes possess good potential for the application on the field emission devices.
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