Browsing by Issue Date, starting with "2009-07-29"

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Interfacial energy levels and related properties of atomic-layer-deposited Al2O3 films on nanoporous TiO2 electrodes of dye-sensitized solar cells
(2009-07-29)
Tien, Ta-Chang
;
Pan, Fu-Ming
;
Wang, Lih-Ping
;
Lee, Chia-Hua
;
Tung, Yung-Liang
Low-temperature (similar to 150 degrees C), atomic-layer-deposited Al2O3 films on nanoporous TiO2 electrodes of dye-sensitized solar cells (DSSCs) were investigated using electron spectroscopy. The power conversion efficiency (PCE) of the DSSCs was increased from 5.7% to 6.5%, an improvement of 14%, with one monolayer of Al2O3 with a thickness of similar to 0.2 nm. The formation of Ti-O-Al(OH)(2) and interfacial dipole layers exhibited a strong influence on the work function of the Al2O3 over-layers, while the thicker Al2O3 over-layers caused the values of valence band maximum and band gap to approach the values associated with pure Al2O3. A work function difference (Delta Phi(A-T)) of 0.4 eV and a recombination barrier height (epsilon(RB)) of 0.1 eV were associated with the highest PCE achieved by the first monolayer of the Al2O3 layer. Thicker Al2O3 over-layers, however, caused significant reduction of PCE with negative Delta Phi(T-A) and increased interfacial energy barrier height (*epsilon(IB)) between the N719 dyes and TiO2 electrodes. It was concluded that the PCE of the DSSCs may correlate with Delta Phi(A-T), epsilon(RB), and *epsilon(IB) resulting from various thicknesses of the Al2O3 over-layers and that interfacial reactions, such as the formation of Ti-O-Al(OH)(2) and dipole layers, play an important role in determining the interfacial energy levels required to achieve optimal performance of dye-sensitized TiO2 solar cells.
Interfacial energy levels and related properties of atomic-layer-deposited Al(2)O(3) films on nanoporous TiO(2) electrodes of dye-sensitized solar cells
(2009-07-29)
Tien, Ta-Chang
;
Pan, Fu-Ming
;
Wang, Lih-Ping
;
Lee, Chia-Hua
;
Tung, Yung-Liang
Low-temperature (similar to 150 degrees C), atomic-layer-deposited Al(2)O(3) films on nanoporous TiO(2) electrodes of dye-sensitized solar cells (DSSCs) were investigated using electron spectroscopy. The power conversion efficiency (PCE) of the DSSCs was increased from 5.7% to 6.5%, an improvement of 14%, with one monolayer of Al(2)O(3) with a thickness of similar to 0.2 nm. The formation of Ti-O-Al(OH)(2) and interfacial dipole layers exhibited a strong influence on the work function of the Al(2)O(3) over-layers, while the thicker Al(2)O(3) over-layers caused the values of valence band maximum and band gap to approach the values associated with pure Al(2)O(3). A work function difference (Delta Phi(A-T)) of 0.4 eV and a recombination barrier height (epsilon(RB)) of 0.1 eV were associated with the highest PCE achieved by the first monolayer of the Al(2)O(3) layer. Thicker Al(2)O(3) over-layers, however, caused significant reduction of PCE with negative Delta Phi(T-A) and increased interfacial energy barrier height (*epsilon(IB)) between the N719 dyes and TiO(2) electrodes. It was concluded that the PCE of the DSSCs may correlate with Delta Phi(A-T), epsilon(RB), and *epsilon(IB) resulting from various thicknesses of the Al(2)O(3) over-layers and that interfacial reactions, such as the formation of Ti-O-Al(OH)(2) and dipole layers, play an important role in determining the interfacial energy levels required to achieve optimal performance of dye-sensitized TiO(2) solar cells.
Observation of localized surface plasmons in spatially controlled array structures
(2009-07-29)
Chou, J. W.
;
Lin, Kao-Chin
;
Lee, Yao-Jen
;
Yuan, Chi-Tsu
;
Hsueh, Fu-Kuo
We observed the reflectance spectra of three different nano-scale array structures of Au-coated silicon nanorods. The trends of the reflectance spectra indicate that the localized surface plasmon modes can be spatially controlled by manipulating geometric parameters, namely the lattice constants of the array. In addition, the experimental results were compared with 2D numerical simulations based on the finite element method. Satisfactory agreement between the experimental observations and numerical results was obtained.
Novel morphology and solidification behavior of eutectic bismuth-tin (Bi-Sn) nanowires
(2009-07-29)
Chen, Shih Hsun
;
Chen, Chien Chon
;
Chao, Chuen Guang
;
材料科學與工程學系
;
Department of Materials Science and Engineering
In the present work we show a simple and robust fabrication process for dense and continuous bismuth-tin (Bi-Sn) eutectic nanowires. The Bi-Sn eutectic nanowires of 200 nm diameter and several tens of mu m, in length were fabricated by a vacuum hydraulic force method. The alloy melt was injected into an anodic aluminum oxide (AAO) template to form nanowires after melt solidification. For this process, nanowires were formed from non-atomic deposition with liquid alloy; in this way, the composition of nanowires can be controlled precisely in stoichiometry. The Bi-Sn melt was restricted inside the AAO which has a low thermo-conduction and long period cooling rate around the melt. On the other hand, the heat flow is along the tube Z-axis and the melt is solidified from the AAO bottom to top because of the open pore on the AAO top. The eutectic nanowires were found to be dense and continuous with a uniform diameter throughout the length of the wires and with a lamellar microstructure along the wires' Z-axis. In addition, the alternative segmental compositions showed that the ratio of tin to bismuth is approximately 33:1. (C) 2009 Elsevier B.V. All rights reserved.
蛍光材料と発光装置
(2009-07-30)
陳登銘
;
戴筱萍
【課題】一連の新奇性を有する化学組成蛍光材料を提供すること。【解決手段】本発明は、化学式をＡm（Ｂａ1-xＥｕx2+）nＰyＯzとし、式中ＡはＬｉ、ＮａおよびＫにより構成された群から選ばれた少なくとも１つであり、かつ０＜ｍ＜１０、０＜ｎ＜１０、０＜ｙ＜１０、ｍ＋ｎ＋ｙ＝３／４ｚ、０．００１＜ｘ＜０．８である一連の蛍光材料を提供する。【選択図】図１
Characterizations of gallium-doped ZnO films on glass substrate prepared by atmospheric pressure metal-organic chemical vapor deposition
(2009-07-31)
Huang, Yen-Chin
;
Li, Zhen-Yu
;
Chen, Hung-hsin
;
Uen, Wu-Yih
;
Lan, Shan-Ming
Ga-doped zinc oxide (ZnO:Ga) films were grown on glass substrate by atmospheric pressure metal-organic chemical vapor deposition (AP-MOCVD) using diethylzinc and water as reactant gases and triethyl gallium (TEG) as an n-type dopant gas. The structural, electrical and optical properties of ZnO:Ga films obtained at various flow rates of TEG ranging from 1.5 to 10 sccm were investigated. X-ray diffraction patterns and scanning electron microscopy images indicated that Ga-doping plays an important role in forming microstructures in ZnO films. A smooth surface with a predominant orientation of (101) was obtained for the ZnO:Ga film grown at a flow rate of TEG=7.5 sccm. Moreover, a lowest resistivity of 3.6 x 10(-4) Omega cm and a highest mobility of 30.4 cm(2) V(-1) s(-1) were presented by the same sample, as evaluated by Hall measurement. Otherwise. as the flow rate of TEG was increased, the average transmittance of ZnO:Ga films increased from 75% to more than 85% in the wavelength range of 400-800 nm, simultaneously with a blue-shift in the absorption edge. The results obtained suggest that low-resistivity and high-transparency ZnO films can be obtained by AP-MOCVD using Ga-doping sufficiently to make the films grow degenerate and effect the Burstein-Moss shift to raise the band-gap energy from 3.26 to 3.71 eV. (C) 2009 Elsevier B.V. All rights reserved.
Effect of Ta2O5 Doping on Electrical Characteristics of SrTiO3 Metal-Insulator-Metal Capacitors
(2009-08-01)
Huang, Ching-Chien
;
Cheng, Chun-Hu
;
Liou, Bo-Heng
;
Yeh, Fon-Shan
;
Chin, Albert
The effect of Ta2O5 doping on electrical characteristics of SrTiO3 (STO) metal-insulator-metal (MIM) capacitors was studied for the first time. Using Ta2O5-doped STO dielectrics, an absolute quadratic voltage coefficient of capacitance (VCC-alpha) of 510 ppm/V-2 and a high capacitance density of similar to 20 fF/mu m(2) are achieved. These are approximately one order of magnitude lower than those of the MIM capacitor fabricated using a pure STO. In addition, the degradation of electrical properties (capacitance variation versus voltage, VCC-alpha, and long-term reliability) after electrical stressing is reduced, compared with that of an MIM capacitor fabricated using a pure STO. (C) 2009 The Japan Society of Applied Physics
Diode-pumped passively mode-locked 1342 nm Nd:YVO(4) laser with an AlGaInAs quantum-well saturable absorber
(2009-08-01)
Huang, S. C.
;
Cheng, H. L.
;
Chen, Yi-Fan
;
Su, K. W.
;
Chen, Y. F.
We demonstrate what we believe to be the first use of AlGaInAs quantum wells (QWs) as a saturable absorber for a diode-pumped passively mode locked Nd:YVO(4) laser at 1342 nm. The QWs are grown on a Fedoped InP substrate that is transparent at lasing wavelength. At an incident pump power of 13.5 W an average output power of 1.05 W with a continuous mode-locked pulse duration of 26.4 ps at a repetition rate of 152 MHz was generated. (C) 2009 Optical Society of America
Role conflicts, emotional exhaustion and health problems: a study of police officers in Taiwan
(2009-08-01)
Wu, Chia-huei
;
經營管理研究所
;
Institute of Business and Management
This study focused on the role conflicts faced by police officers in Taiwan and investigated the relationship between role conflicts, emotional exhaustion and health problems based on the job demands and resources model (JD-R model). Firstly, in addition to work-family conflict, an inter-role conflict, this study identified an intrasender role conflict for police officers called uncompromising-friendly conflict. Secondly, according to the JD-R model, it was hypothesized that emotional exhaustion has a complete mediation effect on the relationships between role conflicts and health problems. The survey data in Huang's study were analysed. A total of 672 police officers at Kaohsiung, Taiwan provided completed data for analysis. Correlation analysis showed that role conflicts, emotional exhaustion and health problems were positively correlated. Results of the structural equation model further suggested that the positive effect of role conflicts on health problems was partially mediated by emotional exhaustion. Copyright (C) 2009 John Wiley & Sons, Ltd.
Adaptation to the edge of chaos in a self-starting Kerr-lens mode-locked laser
(2009-08-01)
Hsu, C. C.
;
Lin, J. H.
;
Hsieh, W. F.
;
光電工程學系
;
Department of Photonics
We experimentally and numerically demonstrated that self-focusing acts as a slow-varying control parameter that suppresses the transient chaos to reach a stable mode-locking (ML) state in a self-starting Kerr-lens mode-locked Ti:sapphire laser without external modulation and feedback control. Based on Fox-Li's approach, including the self-focusing effect, the theoretical simulation reveals that the self-focusing effect is responsible for the self-adaptation. The self-adaptation occurs at the boundary between the chaotic and continuous output regions in which the laser system begins with a transient chaotic state with fractal correlation dimension, and then evolves with reducing dimension into the stable ML state.
Sample size determination for production yield estimation with multiple independent process characteristics
(2009-08-01)
Hsu, Ya-Chen
;
Pearn, W. L.
;
Chuang, Ya-Fei
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
Capability measure for processes yield with single characteristic has been investigated extensively, but is still comparatively neglected for processes with multiple characteristics. Wu and Pearn [Wu, C.W., Pearn, W.L. 2005. Measuring manufacturing capability for couplers and wavelength division multiplexers (WDM). International journal of Advanced Manufacturing Technology 25(5/6), 533-541] proposed a capability index for multiple characteristics called C(PU)(T), which provides an exact measure on process yield for multiple characteristics with each characteristic normally distributed. However, the exact sampling distribution of C(PU)(T)(multiple characteristics) is analytically intractable. In this paper, we apply the bootstrap method for calculating the lower confidence bounds of the index C(PU)(T), and determine the sample size for a specified estimation accuracy. In order to obtain a desired estimation quality assurance, the sample size determination is essential as it provides the accuracy of the lower bound obtained from the bootstrap method. For convenience of applications, we tabulate the sample size required for various designated accuracy for the engineers/practitioners to use. A real-world example from manufacturing process with multiple characteristics is investigated to illustrate the applicability of the proposed approach. (C) 2008 Published by Elsevier B.V.
Effects of Plasma Damage on Metal-insulator-Metal Capacitors and Transistors for Advanced Mixed-Signal/Radio-Frequency Metal-Oxide-Semiconductor Field-Effect Transistor Technology
(2009-08-01)
Weng, Wu-Te
;
Lee, Yao-Jen
;
Lin, Hong-Chih
;
Huang, Tiao-Yuan
;
電子工程學系及電子研究所
The effects of damage on mixed-signal (MS)/radio-frequency (RF) circuits integrated with metal-insulator-metal (MIM) capacitors and advanced metal-oxide-semiconductor field-effect transistors (MOSFETs) are studied in this work. The impact of damage on an MIM oxide is evaluated by connecting its capacitor top metal (CTM) to an upper-level metal with a large antenna ratio (AR(CTM)) used in an actual CTM circuit connected to an interconnect. In addition to the dielectric degradation of a transistor, we also investigate the damage-enhanced negative bias temperature instability (NBTI) degradation of a transistor with its gate electrode connected to an MIM capacitor with a large ARCTM for various gate oxide thicknesses. A model is proposed to explain the experimentally observed dependence of NBTI degradation on AR(CTM) and accurately simulate failure distributions in the presence of plasma damage. (C) 2009 The Japan Society of Applied Physics
The Absolute Stability Analysis in Fuzzy Control Systems with Parametric Uncertainties and Reference Inputs
(2009-08-01)
Wu, Bing-Fei
;
Ma, Li-Shan
;
Perng, Jau-Woei
;
電控工程研究所
;
Institute of Electrical and Control Engineering
This study analyzes the absolute stability in P and PD type fuzzy logic control systems with both certain and uncertain linear plants. Stability analysis includes the reference input, actuator gain and interval plant parameters. For certain linear plants, the stability (i.e. the stable equilibriums of error) in P and PD types is analyzed with the Popov or linearization methods under various reference inputs and actuator gains. The steady state errors of fuzzy control systems are also addressed in the parameter plane. The parametric robust Popov criterion for parametric absolute stability based on Lur'e systems is also applied to the stability analysis of P type fuzzy control systems with uncertain plants. The PD type fuzzy logic controller in our approach is a single-input fuzzy logic controller and is transformed into the P type for analysis. In our work, the absolute stability analysis of fuzzy control systems is given with respect to a non-zero reference input and an uncertain linear plant with the parametric robust Popov criterion unlike previous works. Moreover, a fuzzy current controlled RC circuit is designed with PSPICE models. Both numerical and PSPICE simulations are provided to verify the analytical results. Furthermore, the oscillation mechanism in fuzzy control systems is specified with various equilibrium points of view in the simulation example. Finally, the comparisons are also given to show the effectiveness of the analysis method.
NCTUns tool for wireless vehicular communication network researches
(2009-08-01)
Wang, S. Y.
;
Chou, C. L.
;
資訊工程學系
;
Department of Computer Science
Several goals such as improving road safety and increasing transport efficiency are being pursued in intelligent transportation systems (ITS). Wireless vehicular communication is one technology to achieve these goals. Conducting vehicular experiments on the roads is an approach to studying the effectiveness of wireless vehicular communication. However, such an approach is costly, hard-to-control (repeat), dangerous, and infeasible when many vehicles and people are involved in the field trial. In contrast, the simulation approach does not have these problems. It is a very useful approach and complements the field trial approach. This paper presents NCTUns, an open source integrated simulation platform, for wireless vehicular communication network researches. This tool tightly integrates network and traffic simulations and provides a fast feedback loop between them. Therefore, a simulated vehicle can quickly change its driving behavior such as moving speed and direction when it receives a message from the wireless vehicular communication network. This capability is required by several novel ITS applications such as active collision avoidance systems. In this paper, we present the design, implementation, validation, and performance of this tool. (C) 2009 Elsevier B.V. All rights reserved.
The proximity between C-termini of dimeric vacuolar H(+)-pyrophosphatase determined using atomic force microscopy and a gold nanoparticle technique
(2009-08-01)
Liu, Tseng-Huang
;
Hsu, Shen-Hsing
;
Huang, Yun-Tzu
;
Lin, Shih-Ming
;
Huang, Tsu-Wei
Vacuolar H(+)-translocating inorganic pyrophosphatase [vacuolar H(+)-pyrophosphatase (V-PPase); EC 3.6.1.1] is a homodimeric proton translocase; it plays a pivotal role in electrogenic translocation of protons from the cytosol to the vacuolar lumen, at the expense of PP(i) hydrolysis, for the storage of ions, sugars, and other metabolites. Dimerization of V-PPase is necessary for full proton translocation function, although the structural details of V-PPase within the vacuolar membrane remain uncertain. The C-terminus presumably plays a crucial role in sustaining enzymatic and proton-translocating reactions. We used atomic force microscopy to visualize V-PPases embedded in an artificial lipid bilayer under physiological conditions. V-PPases were randomly distributed in reconstituted lipid bilayers; approximately 43.3% of the V-PPase protrusions faced the cytosol, and 56.7% faced the vacuolar lumen. The mean height and width of the cytosolic V-PPase protrusions were 2.8 +/- 0.3 nm and 26.3 +/- 4.7 nm, whereas those of the luminal protrusions were 1.2 +/- 0.1 nm and 21.7 +/- 3.6 nm, respectively. Moreover, both C-termini of dimeric subunits of V-PPase are on the same side of the membrane, and they are close to each other, as visualized with antibody and gold nanoparticles against 6xHis tags on C-terminal ends of the enzyme. The distance between the V-PPase C-terminal ends was determined to be approximately 2.2 +/- 1.4 nm. Thus, our study is the first to provide structural details of a membrane-bound V-PPase dimer, revealing its adjacent C-termini.
一種即時階層式背景重建與前景偵測之方法
(2009-08-01)
陳祝嵩
;
陳昱廷
本發明揭露一種即時階層式背景重建與前景偵測之方法,可於視訊中進行背景重建與前景偵測,其主要特徵係在於整合了以區塊為基礎(Block-Based)之粗階(Coarse-Level)背景模型(Background Modeling)與以像素為基礎(Pixel-Based)之細階(Fine-Level)背景模型方法。首先,本方法將影像劃分成不互相重疊的影像區塊,並針對每一個區塊建立其粗階背景模型,有了此一模型便可進行快速但形狀較粗略的前景物體偵測。在有了粗略前景偵測結果後,再將此結果饋入(Feed)細階背景模型做進一步的判斷分析。其中在粗階背景重建部份係以一個新發展的區塊描述元(Descriptor)來描述區塊內含資訊的特徵,此一描述元稱為差異均値向量(Difference Mean Vector,DMV)。此外,高斯混和(Gaussian Mixture)方法被使用來對差異均値向量特徵進行粗階背景模型的建構。細階部份則可採用現行習知之以像素為基礎的背景重建方法。另外,一前饋架構(Feed-Forward Framework)亦被揭露來整合粗階背景模型與細階背景模型,其將粗階部份所辨認到的資訊饋入至細階部份,以進行粗階前景偵測結果的細緻化與細階背景模型的更新。
Diode-pumped passively mode-locked 1342 nm Nd:YVO4 laser with an AlGaInAs quantum-well saturable absorber
(2009-08-01)
Huang, S. C.
;
Cheng, H. L.
;
Chen, Yi-Fan
;
Su, K. W.
;
Chen, Y. F.
We demonstrate what we believe to be the first use of AlGaInAs quantum wells (QWs) as a saturable absorber for a diode-pumped passively mode locked Nd:YVO4 laser at 1342 nm. The QWs are grown on a Fedoped InP substrate that is transparent at lasing wavelength. At an incident pump power of 13.5 W an average output power of 1.05 W with a continuous mode-locked pulse duration of 26.4 ps at a repetition rate of 152 MHz was generated. (C) 2009 Optical Society of America
Fabrication of Ni nanowires for hydrogen evolution reaction in a neutral electrolyte
(2009-08-01)
Chen, Po-Chun
;
Chang, Yun-Min
;
Wu, Pu-Wei
;
Chiu, Yu-Fan
;
材料科學與工程學系
Hydrogen evolution reaction in 1 M Na(2)SO(4) was investigated using Ni nanowires in diameter of 250 nm with exposed lengths of 20, 35, and 45 mu m, respectively. The Ni nanowires were fabricated by a direct-current pulse electrodeposition technique using an anodic aluminum oxide template, followed by selective removal of the supporting pore walls. Scanning Electron Microscope images revealed structural stabilities and X-ray diffraction pattern indicated a polycrystalline fcc phase. In current-potential (i-V) polarizations, the Ni nanowires with longer exposed lengths demonstrated larger current responses. Analysis from impedance spectroscopy confirmed increasing double-layer capacitances with longer Ni nanowires. in galvanostatic lifetime experiments, the freestanding Ni nanowires exhibited a reduced overpotential over that of supported ones. Similar procedures were performed for the oxygen evolution reaction in both i-V and lifetime measurements. For the Ni nanowires of 45 pm length, we estimated the energy cost for hydrogen production was 5.24 x 10(5) J/mole. (C) 2009 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.
The proximity between C-termini of dimeric vacuolar H+-pyrophosphatase determined using atomic force microscopy and a gold nanoparticle technique
(2009-08-01)
Liu, Tseng-Huang
;
Hsu, Shen-Hsing
;
Huang, Yun-Tzu
;
Lin, Shih-Ming
;
Huang, Tsu-Wei
Vacuolar H+-translocating inorganic pyrophosphatase [vacuolar H+-pyrophosphatase (V-PPase); EC 3.6.1.1] is a homodimeric proton translocase; it plays a pivotal role in electrogenic translocation of protons from the cytosol to the vacuolar lumen, at the expense of PPi hydrolysis, for the storage of ions, sugars, and other metabolites. Dimerization of V-PPase is necessary for full proton translocation function, although the structural details of V-PPase within the vacuolar membrane remain uncertain. The C-terminus presumably plays a crucial role in sustaining enzymatic and proton-translocating reactions. We used atomic force microscopy to visualize V-PPases embedded in an artificial lipid bilayer under physiological conditions. V-PPases were randomly distributed in reconstituted lipid bilayers; approximately 43.3% of the V-PPase protrusions faced the cytosol, and 56.7% faced the vacuolar lumen. The mean height and width of the cytosolic V-PPase protrusions were 2.8 +/- 0.3 nm and 26.3 +/- 4.7 nm, whereas those of the luminal protrusions were 1.2 +/- 0.1 nm and 21.7 +/- 3.6 nm, respectively. Moreover, both C-termini of dimeric subunits of V-PPase are on the same side of the membrane, and they are close to each other, as visualized with antibody and gold nanoparticles against 6xHis tags on C-terminal ends of the enzyme. The distance between the V-PPase C-terminal ends was determined to be approximately 2.2 +/- 1.4 nm. Thus, our study is the first to provide structural details of a membrane-bound V-PPase dimer, revealing its adjacent C-termini.
Chaos control of new Ikeda-Lorenz systems by GYC partial region stability theory
(2009-08-01)
Ge, Zheng-Ming
;
Ho, Chun-Yen
;
Li, Shih-Yu
;
Chang, Ching-Ming
;
機械工程學系
A new strategy to achieve chaos control by GYC partial region stability theory is proposed. By using the GYC partial region stability theory, the Lyapunov function is a simple linear homogeneous function of error states, the controllers are more simple and have less simulation error because they are in lower degree than that of traditional controllers. Simulation results for a new Ikeda-Lorenz system show the effectiveness of this strategy. Copyright (C) 2008 John Wiley & Sons, Ltd.