Carbon nanotubes synthesized by chemical vapor deposition of pyrolytic methane
碩士 === 中原大學 === 應用物理研究所 === 89 === This thesis mainly expounds the growth of carbon nanotubes (CNTs) by thermal chemical vapor deposition (CVD) on p-type Si wafer coated with transition metal as catalyst. The catalysts used are and FeCo thin film. CNTs synthesized by two kinds of heating methods...
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| Format: | Others |
| Language: | zh-TW |
| Published: |
2001
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| Online Access: | http://ndltd.ncl.edu.tw/handle/73802855496657769632 |
| Summary: | 碩士 === 中原大學 === 應用物理研究所 === 89 ===
This thesis mainly expounds the growth of carbon nanotubes (CNTs) by thermal chemical vapor deposition (CVD) on p-type Si wafer coated with transition metal as catalyst. The catalysts used are and FeCo thin film. CNTs synthesized by two kinds of heating methods were compared in regard to their morphologies、structures and characteristics of field emission.
In the first method，for the pyrolysis of methane microwave-heating thermal CVD (MHT CVD) were used to grow CNTs. The advantages of this method are the shortening of processing time and the output of rich、pure CNTs. The shortages of this method are the difficulty of defining growth temperature and the lack of stability of microwave power. From the images of scanning electron microscope (SEM)，the diameter of CNTs synthesized by this method is about 100 nm；The instability of the microwave power causes the defect-specked walls of CNTs as observed from the tunneling electron microscope (TEM) images；besides，due to the defects along the walls，the characteristics of field emission of these CNTs are not so good，with current density of 0.12 mA/cm2，and turn-on field of 1.2 V/μm.
In the second method，CNTs were synthesized by thermal CVD in a furnace. Growth temperature could be defined ，and other growth parameters were under control due to the stability of the growth environment In this case. From the SEM images，the diameter of these CNTs ranges between 50 to 100 nm；the structure and the field emission characteristics of these tubes are better than former ones，current density of 7 mA/cm2，and turn-on field of 1.35 V/μm，are obtained. Defects in the tubes seem to play a role improving the field emission property of the CNTs.
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