| Summary: | 碩士 === 國立臺灣科技大學 === 光電工程研究所 === 97 === Carbon nanotubes (CNTs) were synthesized on carbon cloth by thermal chemical vapor deposition (TCVD). To enhance the field emission current, catalyst metal at the tip of CNTs was removed by chemical modifications with nitric acid (HNO3). The field emission characteristics of CNTs with various HNO3 immersion time were investigated. As a result, when the HNO3 immersion time was 15 min, the threshold electric field (Eth) has the lowest value of 1.9 V/um. When the immersion time was extended, the Eth increased due to defects at the surface of CNTs. Although the Eth was decreased with the optimal condition of HNO3 treatment, the long-term stability of as treated CNTs was poor. To improve the stability, ZnO nanostructures were synthesized on the surface of the open-end CNTs. Consequently, the long-term stability of the CNTs was improved and an even lower Eth, i.e. 1.5 V/um, was obtained.
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