| Summary: | 碩士 === 國立臺北科技大學 === 機電整合研究所 === 96 === In order to improve the reproducibility of CNTs process, this study integrates the industrial technology and remote intelligent control method into microwave plasma chemical vapor deposition (MPCVD) system. An automatic fuzzy control scheme is used to adjust electromagnetic field distribution, plasma density, and reflected microwave power by E-H tuner position in the MPCVD system. Reflected microwave power as the main feedback signal. The intelligent control includes establishment of database, fuzzification of principal component, membership function, fuzzy inference rules, and defuzzification. The specific micro-structure ratio is a fuzzy singleton to input in fuzzy logic algorithm. This value figured out the corresponding E-H tuner position by database which included the relationship between E-H tuner position and micro-structure. The figured out position output to drive the linear cylinder achieved the corresponding position and started to grow CNTs.
The experimental results shown, an (X, Y) position of (19.3 cm, 10 cm) for E-H tuner adjustment is found to have the best average micro-structure ratio 0.336 (ID/IG ratio), the averaged films thickness is 41.77 μm, the averaged tube diameter is 31.26 nm. On the other hands, an (X, Y) position of (7.3 cm, 13.9 cm), the ID/IG is 1.32 and average films thickness is 9 μm, the averaged tube diameter is 57.78 nm. According to this result, not only micro- structure but also thickness and tube diameter were changed by different E-H tuner position, and each position had its corresponded micro-structure and reproducibility. Compared with these tow micro-structure by field emission test, the result shown that the lower ID/IG ratio the better turn on voltage 0.54 V/μm, but the turn on voltage of higher ID/IG ratio is 0.82 V/μm. Although the turn on voltage changed by different ID/IG ratio, but both CNTs samples had well field emission properties.
The results of contact angle measurement shown, CNTs had the bad wettability because of 145˚ average contact angle. All of the contact angles were not changed by different ID/IG ratio. On the other hands, the electrowetting property changed clearly by the external power source. As the results shown, the lower ID/IG ratio (0.336) the better electrowetting property when voltage during 0~4 V. But the higher ID/IG ratio (1.32) needed a higher voltage about 11 V to change its electrowetting property. Combined with these results of characteristics and MPCVD intelligent control system, this study improved the industrial value of MPCVD system. Therefore, this system could made more applications by high reproducibility CNTs process.
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