Browsing by Author "Hsiao, CS"

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Interfacial microstructure and electrical properties of PT/Al2O3/Si annealed at high temperatures
(2004-11-15)
Chen, SY
;
Hsiao, CS
;
Hsu, JJ
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Pb1+xTiO3 (PT) thin films were deposited on Al2O3(10 nm)/Si using lead acetate trihydrate and titanium isopropoxide with the addition of glycerol (GL) chelating agent as precursors. It was found that perovskite PT phase can be well crystallized at a lower temperature of 600 degreesC and excellent memory properties are obtained. However, with increasing annealing temperature above 700 degreesC, charge-injection mode instead of ferroelectric behavior was detected. Cross-sectional TEM results illustrate that with an increase of annealing temperature and Pb content in the PT films, diffusion envelops and even composition separations were detected in the interface of PT/Al2O3/Si. It was believed that the degradation in the ferroelectric memory properties is strongly related to the change of microstructure and composition in the interface of PT/Al2O3/Si. (C) 2004 Elsevier B.V. All rights reserved.
Tunable growth of ZnO nanorods synthesized in aqueous solutions at low temperatures
(2006-01-01)
Hsiao, CS
;
Peng, CH
;
Chen, SY
;
Liou, SC
;
材料科學與工程學系
Highly arrayed ZnO nanorods were fabricated on the Si substrate buffered with patterned ZnO film (ZnOf/Si) via wet-chemical process. The growth behavior and morphology of single-crystal ZnO nanorods (ZNs) were investigated in terms of the annealing temperatures of the sputtered ZnO film. We found that the growth morphology of ZnO nanorods is strongly dominated by the grain size of the ZnO film on the Si substrate. The ZnOf/Si substrate was annealed at above a critical temperature to promote the crystallization of ZnO phase, and high-resolution transmission electron microscopy demonstrated that both ZNs and ZnOf on Si substrate are coherent. Furthermore, the ZNs seem to nucleate from the concave tip near the grain boundary between two ZnO grains in the ZnO film because of higher surface energy. However, a higher annealing temperature may lead to the formation of a larger ZnO crystal due to the coplanar coalescence behavior of several individual ZnO nanorods. (c) 2006 American Vacuum Society.
Ultraviolet emission in ZnO films controlled by point defects
(2004)
Lin, CC
;
Hsiao, CS
;
Chen, SY
;
Cheng, SY
;
材料科學與工程學系
The undoped ZnO films were grown on silicon (001) substrates by radio frequency magnetron sputtering. The dependence of defect formation and photoluminescence (PL) of ZnO films on the annealing temperature and oxygen mole ratio (OMR) were investigated using X-ray diffraction and PL spectra. A sharp ZnO (002) peak with a strong UV emission peak around 3.28 eV can be obtained for the films annealed in O-2 and N-2 atmospheres. However, the films annealed in nitrogen show strong deep-level emission peaks that vary with the annealing temperature. Below 850 degreesC, Zn interstitials become the dominant point defects, but for the ZnO films annealed at higher temperatures such as 1000 degreesC, oxygen vacancies become the predominant point defects. In contrast, in an oxygen atmosphere, a strong UV emission along with invisible deep-level peaks can be detected for ZnO films sputtered at an OMR of 5% and annealed at 850 degreesC. This result is attributed to the enhanced crystallization and a reduced defect concentration. (C) 2004 The Electrochemical Society.