| Summary: | 碩士 === 國立交通大學 === 電子工程系所 === 96 === In this research, we studied on the pillar-like CNT field emission arrays synthesis with co-deposited multilayer catalyst at low temperatures and try to improve their uniformity and reliability by testing as field emission backlight units (FE-BLUs). According to our group’s previous researches, we could effectively decrease the growth temperature of CNTs by utilizing multilayer catalyst and remarkably improve the reliability of CNTs by utilizing co-deposited catalysts. Firstly, we combined these two techniques to preparing co-deposited multilayer catalyst for synthesis of pillar-like CNTs at low temperatures. As a result, CNTs grown with catalysts of co-deposited Co and Ti on Al (Co-Ti/Al) showed the best morphology and field emission properties, which revealed a low turn-on field (~3.6 V/μm), a high current density of 1272 μA/cm2 under 6V/μm electric field, and superior short-term stability with current variation below 7% under the electric field of 6.7 V/μm in 2 hours. In addition, the photo luminescent image of 1cmx1cm pillar patterns illuminated uniformly. Secondly, we obtained an optimum growth time was determined to be 90 min for synthesis of the pillar-like CNTs at 550℃. Height of CNTs was about 8 μm, which revealed a low turn-on field of 3.5 V/μm, and excellent reliability was shown by the degradation of current below 0.1% under the electric field 6.7 V/μm in 2 hours. Based on the material analysis, the amorphous carbon would increase with increasing the growth time, and then the field emission characteristics became worse. Thirdly, we utilized photolithography to pattern different spacings between the pillar-like CNTs for finding out the optimum field emission characteristics by the compromising between screening-effect and emission area. Accordingly, the optimum electrical characteristics for the pillar-like CNTs with the pillar diameter of 6 μm and the pillar height of 8 μm would happen at the inter-pillar spacing of about 9 μm, which exhibited good electrical characteristics.
Finally, we utilized triode-typed CNT field emission array to reduce the operation voltage, and the beam spreading to improve the emission uniformity. The optimum parameters of the triode field emission device were obtained according to the simulations, the gate-to-emitter length was 2 μm, and the vertical distance between gate and CNTs was 1 μm. And experimental results and the resultant driving voltage was as low as 43 V. In future, this structure is promising for the applications in a planar backlight because of the large-area uniformity and simple fabrication process with low cost.
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