Browsing by Issue Date, starting with "2007-07-31"

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SrTiO3-SiO2 oxide films for possible high-k gate dielectric applications
(2007-07-31)
Lin, Chun-Chieh
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Lai, Li-Wen
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Lin, Chih-Yang
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Tseng, Tseung-Yuen
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電子工程學系及電子研究所
Amorphous thin films of SrTiO3-SiO2 high-k dielectric oxides were deposited on p-Si substrate by sputtering from the targets made by SrTiO3 and SiO2 powder mixtures. The surface morphology, crystal structure, chemical bonding configuration, and depth profile of the composition were investigated by using scanning electron microscopy, glancing incident angle X-ray diffraction, X-ray photoelectron spectroscopy, and Auger electron spectroscopy, respectively. The capacitance-voltage (CV) and current-voltage characteristics were used for demonstrating their electrical properties. The SrTiO3-SiO2 thin films remained as amorphous structures when annealed up to 900 degrees C. The Pt/SrTiO3-SiO2/Si MOS structure 2 had a low leakage current density of similar to 2 x 10(-8) A/cm(2) measured at 100 kV/cm and dielectric constant of 24 for 700 degrees C-annealed film. The films annealed at 600 degrees C showed typical CV characteristics. However, the deformed CV curves were found for films annealed at 700 degrees C due to the diffusion of Ti species in the SrTiO3-SiO2 film into the Si substrate. (C) 2006 Elsevier B.V. All rights reserved.
Liquid crystal alignment on the a-C : H films by Ar plasma ion immersion
(2007-07-31)
Chang, S. J.
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Wu, K. Y.
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Yang, Y. H.
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Hwang, J.
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Wu, Hsin-Ying
A plasma ion immersion treatment has been developed to enhance the liquid crystal (LC) alignment on the hydrogenated amorphous carbon (a-C:H) layer in an inductively coupled plasma (ICP) chamber. No LC alignment was observed for the a-C:H layer tilted at an angle of 0 degrees during the bombardment with plasma ions. The LC alignment occurs for the a-C:H layer tilted at an angle of 30 degrees or 60 degrees. Their pretilt angles (similar to 1.4 degrees) are approximately the same. The azimuthal anchoring strength is 1.98 x 10(-6) J/m(2) at a tilted angle of 30 degrees and 1.14 x 10(-4) J/m(2) at a tilted angle of 60 degrees. The mechanism for the LC alignment is attributed to the oblique incidence of ions within the matrix sheath of non-uniform thickness near the a-C: H surface under a negative pulse bias. The matrix sheath of non-uniform thickness is confirmed by the plasma density distribution in the ICP chamber and the X-ray photoemission spectra across the a-C:H layer. (C) 2007 Elsevier B.V. All rights reserved.
VLSI architecture for the low-computation cycle and power-efficient recursive DFT/IDFT design
(2007-08-01)
Van, Lan-Da
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Lin, Chin-Teng
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Yu, Yuan-Chu
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資訊工程學系
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電控工程研究所
In this paper, we propose one low-computation cycle and power-efficient recursive discrete Fourier transform (DFT)/inverse DFT (IDFT) architecture adopting a hybrid of input strength reduction, the Chebyshev polynomial, and register-splitting schemes. Comparing with the existing recursive DFF/IDFI' architectures, the proposed recursive architecture achieves a reduction in computation-cycle by half. Appling this novel low-computation cycle architecture, we could double the throughput rate and the channel density without increasing the operating frequency for the dual tone multi-frequency (DTMF) detector in the high channel density voice over packet (VoP) application. From the chip implementation results, the proposed architecture is capable of processing over 128 channels and each channel consumes 9.77 mu W under 1.2 V@20MHz in TSMC 0.13 IP8M CMOS process. The proposed VLSI implementation shows the power-efficient advantage by the low-computation cycle architecture.
Run-by-run process control of metal sputter deposition: Combining time series and extended kalman filter
(2007-08-01)
Chen, Juhn-Horng
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Kuo, Tzu-Wei
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Lee, An-Chen
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機械工程學系
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Department of Mechanical Engineering
Subtopic segmentation for small corpus using a novel fuzzy model
(2007-08-01)
Chang, Tao-Hsing
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Lee, Chia-Hoang
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資訊工程學系
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Department of Computer Science
Subtopic segmentation is a critical task in numerous applications, including information retrieval, automatic summarization, essay scoring, and others. Although several approaches have been developed, many are ineffective for specific domains with a small corpus because of the fuzziness of the semantics of words and sentences in the corpus. This paper explores the problem of subtopic segmentation by proposing a fuzzy model for the semantics of both words and sentences. The model has three characteristics. First, it can deal with the uncertainty in the semantics of words and sentences. Secondly, it can measure the fuzzy similarity between the fuzzy semantics of sentences. Thirdly, it can develop a fuzzy algorithm for segmenting a text into several subtopic segments. The experiments, especially for a short text with a small corpus in a specific domain, indicate that the method can efficiently increase the accuracy of subtopic segmentation over previous methods.
Aberration analysis of a wedge-plate display system
(2007-08-01)
Cheng, Yi-Kai
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Chung, Sen-Nien
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Chern, Jyh-Long
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光電工程學系
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Department of Photonics
The aberration characteristics of a wedge-plate display optical system are analyzed. The study shows that a kink-like feature is inherent in the ray-intercept curve due to either the onset of the dark zone in imaging or the coincidence of the ray direction with the vertex. Third-order aberration coefficients are deduced, and the total amount of aberration is investigated to illustrate the basic limitations of image quality in this type of display. The issue of design optimization is also investigated based on the aberration characteristics. A numerical example of a 50 in. display with a 1:10 thickness and a diagonal screen length ratio is also provided. (c) 2007 Optical Society of America.
Dichotomy of photoinduced quasiparticle on CuO2 planes of YBa2Cu3O7 directly revealed by femtosecond polarization spectroscopy
(2007-08-01)
Luo, C. W.
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Chen, L. Y.
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Lee, Y. H.
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Wu, K. H.
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Juang, J. Y.
The dichotomy of photoinduced quasiparticle dynamics in the anisotropic high T, superconductors (YBa2CU3O7) is revealed by using the orientation-resolved ferntosecond reflection spectroscopy in the specially designed thin films. The transient reflectivity Delta R/R along the ab diagonal and b axis are totally different in the slow relaxation process which relates to the opening of the superconducting gap. In addition, the distribution of the temperature evolution of Delta R/R on the CuO2 planes of YBa2Cu3O7 may indicate the d-wave symmetry of the superconducting gap in high T, superconductors. (c) 2007 American Institute of Physics.
High-resolution through-focus metric with two-pitch grating target
(2007-08-01)
Shyu, Deh-Ming
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Lu, Mao-Hong
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Ko, Chun-Hung
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光電工程學系
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Department of Photonics
Through-focus focus-metric is a method that is used to analyze images on a fixed plane with the help of focus-metric values when the target moves through the focus. In this study, an optical microscope having a magnification of 250x is constructed. A two-pitch grating target is imaged on a CCD detector and through-focus image data are measured. In addition, the optical field on the CCD detector is simulated using the boundary element method and physical optics propagation. By comparing the measured focus-metric signatures with the simulated signatures, information regarding the linewidth is obtained. The results show that the through-focus focus-metric method is a very sensitive method that can be used for measuring parameters such as the linewidth. Thus, a nanoscale resolution can be achieved. (C) 2007 Elsevier B.V. All rights reserved.
Data hiding in binary images with distortion-minimizing capabilities by optimal block pattern coding and dynamic programming techniques
(2007-08-01)
Lee, I-Shi
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Tsai, Wen-Hsiang
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資訊工程學系
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Department of Computer Science
A new method for data hiding in binary images based on block pattern coding and dynamic programming with distortion-minimizing capabilities is proposed. Up to three message data bits can be embedded into each 2 x 2 block in an input image by changing the block's pixel pattern into another, which represents the value of the message data bits as a code according to a block pattern encoding table. And extraction of hidden message data is accomplished by block pattern decoding. To minimize the resulting image distortion, two optimization techniques are proposed. The first is to use multiple block pattern encoding tables, from which an optimal one is selected specifically for each input image, and the second is to use a dynamic programming algorithm to divide the message data into bit segments for optimal embedding in a sense of minimizing the number of binary bit flippings. Accordingly, not only more data bits can be embedded in an image block on the average, but the resulting image distortion is also reduced in an optimal way. Experimental results are also included to show the effectiveness of the proposed approach.
A short-term capacity trading method for semiconductor fabs with partnership
(2007-08-01)
Wu, Muh-Cherng
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Chang, Wen-Jen
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工業工程與管理學系
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Department of Industrial Engineering and Management
This paper presents a capacity trading method for two semiconductor fabs that have established a capacity-sharing partnership. A fab that is predicted to have insufficient capacity at some workstations in a short-term period (e.g. one week) could purchase tool capacity from its partner fab. The population of such a capacity-trading portfolio may be quite huge. The proposed method involves three modules. We first use discrete-event simulation to identify the trading population. Secondly, some randomly sampled trading portfolios with their performance measured by simulation are used to develop a neural network, which can efficiently evaluate the performance of a trading portfolio. Thirdly, a genetic algorithm (GA) embedded with the developed neural network is used to find a near-optimal trading portfolio from the huge trading population. Experiment results indicate that the proposed trading method outperforms two other bench-marked methods in terms of number of completed operations, number of wafer outs, and mean cycle time. (c) 2006 Elsevier Ltd. All rights reserved.
Vortex ratchet effect in a niobium film with spacing-graded density of pinning sites
(2007-08-01)
Wu, T. C.
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Horng, Lance
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Wu, J. C.
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Cao, R.
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Kolacek, Jan
The vortex propagation exhibits rectification effect in Nb superconductors with spacing-graded density of holes. A rectified dc voltage is obtained when the vortex lattice is driven by ac current. The asymmetric geometry of the pinning array produces a significant influence on the vortex motion. The rectified voltage depends considerably on the amplitude of the applied ac current and the magnetic field. The experimental results reveal a drastic change of the vortex rectification for magnetic field above/below the first matching field. The reason may be that the interstitial vortices are formed in the film above the first matching field. A reversible vortex motion is induced by the interstitial vortices for the field above the first matching field. (c) 2007 American Institute of Physics.
Low-voltage organic thin film transistors with hydrophobic aluminum nitride film as gate insulator
(2007-08-01)
Zan, Hsiao-Wen
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Yen, Kuo-Hsi
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Liu, Pu-Kuan
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Ku, Kuo-Hsin
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Chen, Chien-Hsun
This paper reports on the low-voltage (< 5 V) pentacene-based organic thin film transistors (OTFTs) with a hydrophobic aluminum nitride (AlN) gate-dielectric. In this work, a thin (about 50 nm), smooth (roughness about 0.18 nm) and low-leakage AlN gate dielectric is obtained and characterized. The AlN film is hydrophobic and the surface free energy is similar to the organic or the polymer films. The demonstrated AlN-OTFTs were operated at a low-voltage (3-5 V). A low-threshold voltage (-2V) and an extremely low-subthreshold swing (similar to 170 mV/dec) were also obtained. Under low-voltage operating conditions, the on/off current ratio exceeded 106, and the field effect mobility was mobility was 1.67 cm(2)/V s.(c) 2006 Elsevier B.V. All rights reserved.
High-performance polycrystalline-silicon TFT by heat-retaining enhanced lateral crystallization
(2007-08-01)
Liu, Po-Tsun
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Wu, Hsing-Hua
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光電工程學系
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顯示科技研究所
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Department of Photonics
High-performance low-temperature polycrystalline-silicon thin-film transistors (TFTs) have been fabricated by heat-retaining enhanced crystallization (H-REC). In the H-REC technology, a heat-retaining capping layer (HRL) is applied on the prepattern amorphous silicon islands to slow down the heat dissipation effectively. It thereby retains long duration of melting process and further enhances poly-Si-grain lateral growth. With a single shot of laser irradiation, the location-controllable poly-Si active layer with 7-mu m length of grain size can be formed successfully. In addition, in this letter, the H-REC poly-Si TFT with dual gates is studied to enhanced electrical performance and stability.
Hybrid white-light emitting-LED based on luminescent polyfluorene polymer and quantum dots
(2007-08-01)
Chou, Cheng-Hsuan
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Yang, Chung-He
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Hsu, Chain-Shu
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Chen, Teng-Ming
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應用化學系
We report the fabrication and electroluminescence (EL) characterization of a white-emitting hybrid organic/inorganic light emitting device (LED) by integrating core-shell CdSe/ZnS quantum dots (QDs) acting as a yellow emitter and polyfluorenes as the blue emitter in a multilayered structure. The hybrid white-emitting device was fabricated by spin-coating QDs in varied concentrations onto the layer of polyfluorenes with different functional groups (i.e., sulfur-containing PF1 and PFO). Depending on the QDs concentrations and the design of the hybrid LED, our device is able to exhibit either electroluminescence from QDs or a combination of both PF and QD. The EL spectra at different driving voltages, I-V characteristics, and EL chromaticity of the LEDs based on PF1/QD and PFO/QD LEDs have been measured, investigated, and compared, respectively.
Statistical study on the temperature dependence of the turn-on characteristics for p-type LTPS TFTs
(2007-08-01)
Kuo, Yan-Fu
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Tai, Ya-Hsiang
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光電工程學系
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顯示科技研究所
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Department of Photonics
In recent years, low temperature polycrystalline silicon (LTPS) thin-film transistor (TFT) has been widely investigated for various applications to system-on-panel (SOP) technology. However, due to the complexity of grain boundary trap properties, the conducting behaviors of various LTPS TFTs are difficult to be analyzed systematically. In this paper, the common and device-dependent thermal effects are studied to understand the conduction mechanism in the UPS TFTs. (c) 2007 Elsevier Ltd. All rights reserved.
Undisturbed sampling and laboratory shearing tests on a sand with various fines contents
(2007-08-01)
Huang, A. B.
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Huang, Y. T.
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土木工程學系
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Department of Civil Engineering
The effects of plastic or non-plastic fines on the static and cyclic strength of sand have been a subject of laboratory studies for many decades. These studies have not lead to a concensus as to how fines can affect the behavior of sand. Earlier studies have mostly been limited to tests on reconstituted specimens. Some of the controversies stem from the concerns that reconstituted specimens may not be able to duplicate the soil fabric in the field. The authors used Laval sampler to retrieve high quality samples with a wide range of fines contents in Central Western Taiwan. A test site was developed in Yuan Lin Township where standard penetration test (SPT), seismic piezocone (SCPTU) and field shear wave velocity (V-s) measurements were performed in addition to Laval sampling. A series of monotonic and cyclic triaxial tests with V-s measurements were conducted on natural and reconstituted Yuan Lin Soil (YLS) specimens with fines contents ranging from 18 to 89%. While the study confirmed some of the earlier findings which indicated that fines tend to weaken the soil specimens, the results also showed that the effects of fines may be exaggerated according to tests on reconstituted specimens.
Experimental study of demolding properties on stereolithography tooling
(2007-08-01)
An, Chao-Chyun
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Chen, Ren-Haw
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機械工程學系
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Department of Mechanical Engineering
Direct tooling using stereolithography (SL) photopolymer has been developed as rapid tooling for short-run injection molds. However, the tool strength, thermal conductivity, and erosion resistance of SL mold are lower than that of the conventional metal mold. Previous study has showed that the tool life was limited under 200 shots and tool damage often occurs during part ejection. In this paper, experimental data from a demolding properties test are presented and discussed. The experiments were performed using various cooling time, hold pressure, and mold temperature. The experimental data were analyzed by measuring demolding force and surface roughness to evaluate tool life and failure mechanism in order to obtain a working range for the process parameters. The test result shows that the demolding force has close relation with cooling time and mold temperature.
Nonadditive interactions in protein folding: The Zipper model of cytochrome c
(2007-08-01)
Morozov, A. N.
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Shiu, Y. J.
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Liang, C. T.
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Tsai, M. Y.
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Lin, S. H.
Hydrogen exchange experiments (Krishna et al. in J. Mol. Biol. 359:1410, 2006) reveal that folding-unfolding of cytochrome c occurs along a defined pathway in a sequential, stepwise manner. The simplified zipper-like model involving nonadditive coupling is proposed to describe the classical "on pathway" folding-unfolding behavior of cytochrome c. Using free energy factors extracted from HX experiments, the model can predict and explain cytochrome c behavior in spectroscopy studies looking at folding equilibria and kinetics. The implications of the proposed model are discussed for such problems as classical pathway vs. energy landscape conceptions, structure and function of a native fold, and interplay of secondary and tertiary interactions.
A semiparametric method for predicting bankruptcy
(2007-08-01)
Hwang, Ruey-Ching
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Cheng, K. F.
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Lee, Jack C.
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管理科學系
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資訊管理與財務金融系註：原資管所+財金所
Bankruptcy prediction methods based on a semiparametric logit model are proposed for simple random (prospective) and case-control (choice-based; retrospective) data. The unknown parameters and prediction probabilities in the model are estimated by the local likelihood approach, and the resulting estimators are analyzed through their asymptotic biases and variances. The semiparametric bankruptcy prediction methods using these two types of data are shown to be essentially equivalent. Thus our proposed prediction model can be directly applied to data sampled from the two important designs. One real data example and simulations confirm that our prediction method is more powerful than alternatives, in the sense of yielding smaller out-of-sample error rates. Copyright (C) 2007 John Wiley & Sons, Ltd.
Biodegradation of endosulfan-contaminated soil in a pilot-scale reactor-bio augmented with mixed bacterial culture
(2007-08-01)
Kumar, Mathava
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Philip, Ligy
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環境工程研究所
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Institute of Environmental Engineering
A novel mixed bacterial culture was enriched from an endosulfan (6, 7, 8, 9, 10, 10 - hexachloro-1, 5, 5a, 6, 9, 9a-hexahydro-6, 9-methano-2, 3, 4-benzo (e) dioxathiepin-3-oxide) processing industrial surface soil. The cultures were successful in the degradation of aqueous phase endosulfan in both aerobic and anaerobic conditions. Using the cultures, endosulfan degradation in silty gravel with sand (GM) was examined via pilot scale reactor at an endosulfan concentration of 0.78 0.01 mg g(-1) of soil, and optimized moisture content of 40 1%. During operation, vertical spatial variability in endosulfan degradation was observed within the reactor. At the end of 56 days, maximum endosulfan degradation efficiency of 78 0.2% and 86.91 0.2% was observed in the top and bottom portion of the reactor, respectively. Both aerobic and anaerobic conditions were observed within the reactor. However, endosulfan degradation was predominant in anaerobic condition and the total protein concentration in the reactor was declined progressively down the soil depth. Throughout the study, no known intermediate metabolites of endosulfan reported by previous researchers were observed.