Browsing by Author "Cheng, CP"

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Effects of doping concentration and annealing temperature on properties of highly-oriented al-doped ZnO films
(2006-01-18)
Kuo, SY
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Chen, WC
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Lai, FI
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Cheng, CP
;
Kuo, HC
Transparent and conductive high-preferential c-axis-oriented Al-doped zinc oxide (ZnO:Al, AZO) thin films have been prepared by the sol-gel route. Film deposition was performed by spin-coating technique on Si(1 0 0) and glass substrate. Structural, electrical and optical properties were performed by XRD, SEM, four-point probe, photoluminescence (PL) and UV-VIS spectrum measurements. The effects of annealing temperature and dopant concentration on the structural and optical properties are well discussed. It was found that both annealing temperature and doping concentration alter the microstructures of AZO films. Also, PL spectra show two main peaks centered at about 380 nm (UV) and 520 nm (green). The variation of UV-to-green band emission was greatly influenced by annealing temperatures and doping concentration. Reduction in intensity ratio of UV-to-green might possibly originate from the formation of Al-O bonds and localized Al-impurity states. The minimum sheet resistance of 10(4)ohm/rectangle was obtained for the film doped with 1.6mol% Al, annealed at 750 degrees C. Meanwhile, all AZO films deposited on glass are very transparent, between 80% and 95% transmittance, within the visible wavelength region. These results imply that the doping concentration did not have significant influence on transparent properties, but improve the electrical conductivity and diversify emission features. (c) 2005 Elsevier B.V. All rights reserved.
Ultraviolet lasing of sol-gel-derived zinc oxide polycrystalline films
(2006-04-01)
Kuo, SY
;
Lai, FI
;
Chen, WC
;
Cheng, CP
;
Kuo, HC
The effect of post-annealing on sol-gel-derived ZnO films has been investigated. For these films, structural investigations including analyses of surface morphology and microstructures were carried out by X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). Also, optical properties were determined by photoluminescence analysis, ellipsometry and optical pumping measurement. The XRD results indicate that the (002) peak will predominate with increasing annealing temperature. SEM images show that grain size increased with annealing temperature. Moreover, photoluminescence spectra revealed the enhancement in UV emission intensity with annealing temperature, which was attributed to an improvement in crystal quality. Room-temperature ultraviolet random lasing action was observed in the ZnO films. The threshold intensity for the lasing was estimated to be similar to 70 kW/cm(2). Furthermore, it was found that the formation of random laser action is affected by post-annealing, which is associated to the presence of a high-gain medium and efficient light scattering.
Using learning classifier system for making investment strategies based on institutional analysis
(2004)
Lin, JY
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Cheng, CP
;
Tsai, WC
;
Chen, AP
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資訊管理與財務金融系註：原資管所+財金所
The artificial intelligence can dynamically learn and adapt to the change of environments for maximizing the desired goals. This paper conducts simulation experiment to evolve learning classifier system (LCS) for short-term stock forecast decision. Since stock price trend is influenced by unknown and unpredictable surroundings, using LCS to model the fluctuations on financial market allows for the capability to discover the patterns of future trends. Furthermore, the institutional investment is the main consideration of this research by implementing LCS for making strategies. More specifically, LCS is capable of evolving from generation to generation, and in this way can provide the highest profit for future decision-making. In simulation work using real financial data, it is found that LCS produces great profits, and is quite practical for investors.