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[摘要]：In this study, carbon nanotubes (CNTs) were synthesized on a catalyst of ZnO nanorods using thermal chemical vapor deposition. ZnO nanorods were coated on silicon substrates by a hydrothermal process. The CNT growth temperature was maintained at 900 degrees C at an ambient pressure. Methane and argon gases are used for the CNT synthesis. In this work, scanning electron microscopy (SEM) and transmission electron microscopy images were used to observe the surface morphology and sidewall structure, energy-dispersive spectrometry (EDS) was used to identify and analyze the chemical composition of the surface of the CNTs, and Raman spectroscopy was employed to investigate the CNT structures. The research reveals that the carbon nanotubes grown on ZNO nanorods show a multiwalled structure with defective graphite sheets on the walls. The SEM images show that the surface of CNTs grown on the ZnO nanorod catalyst were covered by the nanonode carbon nanoparticles. Raman spectra show that the appearance of the relatively strong D peaks in CNT films grown on ZnO catalyst can possibly result from the existence of nanonodes and the structural defects on the nanotube's graphite sheets. EDS results reveal that the CNTs grown on ZnO nanorods do not need any purification process to optimize the field-emission characteristics of the CNTs. Field-emission tests indicate that the CNT grown on ZnO catalyst films have a low turn-on emission field and high emission current density. The Fowler-Nordheim plot showed a good linear fit, indicating that the emission current of CNTs follows Fowler-Nordheim behavior. The authors attributed the improvement of field-emission properties to the change in the electronic geometrical structure of the local emission region in CNTs. (C) 2008 American Vacuum Society. |
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