Browsing by Author "Huang, Chien-Sheng"

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Field emission properties of CNT-ZnO composite materials
(2009-02-01)
Huang, Chien-Sheng
;
Yeh, Chun-Yu
;
Chang, Yung-Huang
;
Hsieh, Yi-Min
;
Ku, Chien-Yeh
CNT-ZnO composite materials were successfully grown by thermal chemical vapor deposition (thermal CVD). First, Multiwalled Carbon nanotubes were synthesized in the temperature range of 500-700 degrees C. After coating Au nanoparticles on such grown CNTs, ZnO nanowires were synthesized via Zn evaporation method at 500 degrees C. SEM images showed that these CNT-ZnO composites were spinous, and XRD analyses showed that the spinal ZnO were crystalline. The turn-on field of CNT-ZnO composite materials with 500 degrees C growth temperature of underlying CNTs was 3.72 V/mu m, which was 5.58 V/mu m for CNTs grown at 500 degrees C. It was also found that the higher temperature (<550 degrees C) the underlying CNTs were grown at, the better field emission properties CNT-ZnO composite materials have. The WIG ratio from Raman spectroscopy of CNTs decreased as the growth temperature of CNTs increased. The graphitization of underlying CNTs played an important role in the Field emission of CNT-ZnO composite materials. (c) 2008 Elsevier B.V. All rights reserved.
Growth Mechanism of Self-Assembled TixWyO Nanotubes Fabricated by TiW Alloy Anodization
(2018-01-01)
Chang, Yung-Huang
;
Chen, Yuan-Tsung
;
Huang, Chien-Sheng
;
Lu, Chia-Ling
;
Lee, Shih-Hung
Nanostructures, such as nanodots and nanorods, have been fabricated by the anodization process with an aid of anodic aluminum oxide (AAO) for several decades. However, tubular nanostructures have not been reported by using an AAO-assistant anodization technology until now. In this study, we successfully synthesized self-organized TixWyO nanotubes with cap structures for the first time by using a two-step anodization process from Al-coated TiW alloy layers. The TixWyO nanotubes were observed only in the shaped pores of AAO with large enough pore size, and otherwise the nanostructures would become solid rods due to the aggregation of TixWyO. The wall of nanotubes was similar to 30% inside the pores and the other similar to 70% penetrated into the AAO template. Furthermore, no tubular nanostructures were found unless the percentage of W element in TiW alloys is larger than 50%, attributing to the formation of a void by oxygen bubbles arising from the oxidation reaction of tungsten metal. Besides, the height of the nanotubes is limited by an electric field of 0.82 GV/m due to the dielectric breakdown effect. Finally, a bottom-up growth mechanism at the oxide/metal interface is proposed, based on the observation of the cap structure on the top of the tubular architecture. (C) The Author(s) 2018. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License.