| Summary: | 碩士 === 國立嘉義大學 === 光電暨固態電子研究所 === 98 === In this research, the conductivity and diameters of carbon nanotubes (CNT) are investigated by adjusting various synthetic process parameters of nickel-catalyzed thermal chemical vapor deposition (CVD), including pressure, catalyst thickness, and different pretreatment methods. The results of this work can be applied to the fabrication of laterally grown carbon nanotubes devices.
It is found that the diameters of the nanotubes can be controlled
by the initial thickness of the catalyst layer and the synthetic pressure. Better degrees of graphitization are achieved in lower pressure growth. The diameters, the lengths, and the densities of CNT are affected by the catalyst thickness.
It is also found that the pretreatment methods are important for CNT growth. CNT growth on plasma-pretreated samples is better at atmospheric pressure than at low pressure. The optimal pretreatment time for samples pretreated by nitric acid at the concentration of 3M is 155 seconds. CNTs grow on nitric-acid-pretreated samples at atmospheric pressure ; they have better degrees of graphitization, thus, less defects.
The above synthetic conditions obtained by planar substrates are applied to fabricate laterally grown CNT at atmospheric pressure. It is good for carbon nanotubes device at ATM pressure. The lowest CNT contact resistance ever achieved is 5K ohm with the growth temperature of 800℃ and the flow of hydrogen (200 sccm) and methane (400 sccm).
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