Browsing by Author "Wang, Shun-Min"

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Fabrication and Characteristics of Self-Aligned ZnO Nanotube and Nanorod Arrays on Si Substrates by Atomic Layer Deposition
(2010)
Chang, Yung-Huang
;
Wang, Shun-Min
;
Liu, Chien-Min
;
Chen, Chih
;
材料科學與工程學系
Vertically self-aligned ZnO nanorods and nanotubes are fabricated on Si substrates by atomic layer deposition with the assistance of anodic aluminum oxide at 250 degrees C. These nanostructures are equal in height, isolated, and vertical to the Si substrate. With 550 deposition cycles, we can fabricate regular arrays of ZnO nanorods with an average diameter of 70 nm and with a height of 470 nm. In particular, the wall thickness of the nanotubes can be controlled precisely by using the atomic layer deposition approach. The measured wall thickness is 18.5 perpendicular to 1 nm after 250 deposition cycles, which yields a growth rate of 0.075 nm/cycle. A polycrystalline structure for both ZnO nanorods and nanotubes was confirmed by a transmission electron microscope and selected area diffraction pattern. Compared with the ZnO films and nanorods, the fabricated ZnO nanotubes exhibit an excellent performance on photoluminescence characteristics due to their larger surface area. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3489953] All rights reserved.
Fabrication of ordered Ta(2)O(5) nanodots using an anodic aluminum oxide template on Si substrate
(2007-04-01)
Yang, Ching-Jung
;
Chen, Chili
;
Wu, Pu-Wei
;
Shieh, Jia-Min
;
Wang, Shun-Min
Ordered arrays of Ta(2)O(5) nanodots were prepared using anodic aluminum oxide (AAO) as a template to support localized oxidation of TaN. Films of TaN (50 nm) and Al (1.5 mu m) were deposited successively on p-type Si wafers and followed by a two-step anodization process at 40 V using oxalic acid as the electrolyte. The first anodization promoted growth of irregular AAO from overlying Al film. After chemical etching, the second anodization was performed to develop well-organized AAO channels and initiate oxidation of underlying TaN film to form tantalum oxide nanodots at the AAO pore bottoms. X-ray photoelectron spectroscopy results confirmed the chemical nature of nanodots as stoichmetric Ta(2)O(5), X-ray diffraction demonstrated the amorphous characteristic of Ta(2)O(5). As shown in field-emission scanning electron microscopy and transmission electron results, the Ta(2)O(5) nanodots exhibited a hillock structure 80 nm in diameter at the bottom and 50 nm in height. We also synthesized 30-nm nanodots by adjusting AAO formation electrochemistry. This demonstrates the general applicability of the AAO template method for nanodot synthesis from nitride to oxide at a desirable size.
Low-temperature growth of ZnO nanorods in anodic aluminum oxide on Si substrate by atomic layer deposition
(2007-01-15)
Yang, Ching-Jung
;
Wang, Shun-Min
;
Liang, Shih-Wei
;
Chang, Yung-Huang
;
Chen, Chih
Low-temperature growth of self-organized ZnO nanorods on Si substrate is achieved using anodic aluminum oxide and atomic layer deposition at 250 degrees C without catalyst or seed layer. Photoluminescence spectrum indicates that the ZnO nanorod arrays exhibit a blue/green luminescence at 480 nm. In addition, the nanorod arrays demonstrate excellent field-emission properties with a turn-on electric field of 6.5 V mu m(-1) and a threshold electric field of 9.8 V mu m(-1), which are attributed to the perfectly perpendicular alignment of ZnO nanorods to the Si substrate. (c) 2007 American Institute of Physics.