Browsing by Issue Date, starting with "2005-04-30"

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Characterization and conductive coating of phosphors for improved brightness
(2005-04-30)
Chang, CH
;
Chiou, BS
;
Chen, KS
;
Ho, JC
;
電子工程學系及電子研究所
In this study, the phosphors used in CRTs are coated with In2O3 conductive layer derived from the hydrolysis of indium chloride. The conductive coating retards/eliminates charging-up on the phosphor surface during the bombardment of the electrons and improves the cathodoluminescent brightness of the phosphor. However, the non-emissive conductive coating also degrades the cathodoluminescent brightness when it is too thick. The cathodoluminescent brightness increases initially with the amount of coating, reaches a maximum at 10 wt.% InCl3, and decreases with further increase of coating. It is found that with a 10 wt.% InCl3 coating, the brightness of phosphor increases by 20% at 500 V and 1 mu A. (c) 2004 Published by Elsevier B.V.
Hybrid S- to L-band fiber amplifier module with coupled structure
(2005-05-01)
Yeh, CH
;
Chi, S
;
光電工程學系
;
Department of Photonics
Reoxidation behavior of high-nitrogen oxynitride films after O-2 and N2O treatment
(2005-05-01)
Lin, BC
;
Chang, KM
;
Lai, CH
;
Hsieh, KY
;
Yao, JM
Reoxidation of a high-nitrogen ultrathin oxynitride (similar to 1.3nm) has been studied. The reoxidation is conducted using an alternation of nitrous oxide and oxygen gas in rapid thermal oxidation (RTO). The new finding in this study is the zig-zag characteristic of the oxidation rate by O-2 and N2O. It is clear that the N2O oxidation rate is almost independent of the concentration of nitrogen in oxynitride through out the rapid thermal oxidation process, but the O2 oxidation rate is not.
Influence of dislocation density on photoluminescence intensity of GaN
(2005-05-01)
Falth, JF
;
Gurusinghe, MN
;
Liu, XY
;
Andersson, TG
;
Ivanov, IG
The influence of dislocation density on photoluminescence intensity is investigated experimentally and compared to a model. GaN samples were grown by molecular beam epitaxy and metal-organic chemical vapour deposition. Different growth parameters and thicknesses of the layers resulted in different dislocation densities. The threading dislocation density, measured by atomic force microscopy, scanning electron microscopy and X-ray diffraction, covered a range from 5 x 10(8) to 3 x 10(10) cm(-2). Carrier concentration was measured by capacitance-voltage-, and Hall effect measurements and photoluminescence at 2 K was recorded. A model which accounts for the photoluminescence intensity as a function of dislocation density and carrier concentration in GaN is developed. The model shows good agreement with experimental results for typical GaN dislocation densities, 5 x 10(8)-1 x 10(10) cm(-2), and carrier concentrations 4 x 10(16)-1 x 10(18) cm(-3). © 2005 Elsevier B.V. All rights reserved.
Switchable dual-wavelength NRZ-to-RZ data-format transformer using non-DC-biased and synchronously modulated laser diode
(2005-05-01)
Chang, YC
;
Lin, YH
;
Liao, YS
;
Lin, GR
;
光電工程學系
The switchable dual-wavelength and wavelength-converted nonretum-to-zero-to-return-to-zero (NRZ-to-RZ) data transformation is demonstrated by externally seeding a synchronously sinusoidal-modulated laser diode with an optical pseudorandom bit sequence data at 1 Gbps. A maximum wavelength tuning range of 30 nm with an SMSR of greater than 36 dB is obtained. 1 Gbps on/off keying of single-mode RZ data pulse-train generated by externally seeding synchronously sinusoidal-modulated laser diode is demonstrated.
The molecular mechanism of actinomycin D in preventing neointimal formation in rat carotid arteries after balloon injury
(2005-05-01)
Wu, CH
;
Pan, JS
;
Chang, WC
;
Hung, JS
;
Mao, SJT
The pathological mechanism of restenosis is primarily attributed to excessive proliferation of vascular smooth muscle cells (SMC). Actinomycin D has been regarded as a potential candidate to prevent balloon injury-induced neointimal formation. To explore its molecular mechanism in regulating cell proliferation, we first showed that actinomycin D markedly reduced the SMC proliferation via the inhibition of BrdU incorporation at 80 nM. This was further supported by the G1-phase arrest using a flowcytometric analysis. Actinomycin D was extremely potent with an inhibitory concentration IC50 at 0.4 nM, whereas the lethal dose LD50 was at 260 mu M. In an in vivo study, the pluronic gel containing 80 nM and 80 lMactinomycin D was applied topically to surround the rat carotid adventitia; the thickness of neointima was substantially reduced (45 and 55%, respectively). The protein expression levels of proliferating cell nuclear antigen ( PCNA), focal adhesion kinase (FAK), and Raf were all suppressed by actinomycin D. Extracellular signal-regulated kinases (Erk) involved in cell-cycle arrest were found to increase by actinomycin D. These observations provide a detailed mechanism of actinomycin D in preventing cell proliferation thus as a potential intervention for restenosis.
A novel algal toxicity testing technique for assessing the toxicity of both metallic and organic toxicants
(2005-05-01)
Lin, JH
;
Kao, WC
;
Tsai, KP
;
Chen, CY
;
環境工程研究所
This study presents a closed-system algal toxicity test technique that is capable of detecting the effects of both organic and metallic toxicants. Toxicity testing was conducted by transferring adequate amounts of algal suspension, dilution water (with culture growth medium), and toxicants into 300-mL BOD bottles. The BOD bottles were completely filled up with no head-space left. The initial cell density and the exposure time were 15,000 cells/mL and 48 h, respectively. The performance of the above test method was evaluated using three heavy metals and six organic toxicants based on three different test endpoints, i.e., dissolved oxygen production, algal growth rate, and cell density. The proposed test revealed excellent test sensitivity and reproducibility. Currently, none of the existing algal toxicity test protocols is adequate for assessing the toxicity of organic chemicals. The closed-system algal toxicity tests developed by previous researchers also may not be ideal because the enlarged headspace and/or enriched bicarbonate buffer may result in either underestimations of the exposure concentrations or insensitive responses to both heavy metals and organic toxicants. Compared to the aforementioned algal toxicity test methods, the proposed technique in the present study has a more general applicability under conditions such as effluent samples containing both metals and organic toxicants or samples with unknown compositions. (c) 2005 Elsevier Ltd. All rights reserved.
Aplication of plasma immersion ion implantation on seeding copper electroplating for multilevel interconnection
(2005-05-01)
Chiu, SY
;
Wang, YL
;
Chang, SC
;
Feng, MS
;
材料科學與工程學系
In this study, an effective seeding technology, plasma immersion ion implantation of palladium (PIII Pd), was proposed to achieve defect-free gap filling for copper electroplating (Cu-ECP). It was found that a threshold dosage (similar to 5.2 x 10(18) m(-2)) of PIII I'd was required to drive Cu-ECP and the dependence of Pd dosage on the implantation time was quasi-linear. The thickness of electroplated copper films increased as the Pd dosage increased. Too high a Pd dosage caused a rough copper film with high resistivity (> 10 mu Omega cm) while too low a I'd dosage resulted in an insufficient nucleation site for Cu-ECP, leading to poor film adhesion. In addition, a higher substrate bias of PIII was suggested to enhance the gap-filling capability of Cu-ECP and the Cu(111) formation of electroplated copper films. (c) 2004 Elsevier B.V. All rights reserved.
Ti2ZrO phases formed in the titanium and zirconia interface after reaction at 1550 degrees C
(2005-05-01)
Lin, KL
;
Lin, CC
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Hot-pressed 3 mol% Y2O3 partially stabilized ZrO2 was reacted with titanium at 1550&DEG; C/30 min. The interface was characterized by analytical transmission microscopy (transmission electron microscopy/energy-dispersive spectroscopy). The lamellar and the spherical Ti2ZrO as well as the orthorhombic β'-Ti were found to exist in the titanium side after cooling down to room temperature. The crystal structures of the lamellar and the spherical Ti2ZrO were orthorhombic and hexagonal, respectively. On heating, the dissolution of a large amount of zirconium and oxygen into titanium gave rise to the metastably supersaturated disordered α-Ti(Zr, O) solid solution where two different Ti2ZrO phases subsequently precipitated, while the β-Ti coexisting with α-Ti at high temperatures was transformed to the orthorhombic β'-Ti during cooling. The spherical hexagonal Ti2ZrO was an ordered structure, with Zr and O occupying substitutional and interstitial sites, respectively. The orientation relations between oc-Ti and the lamellae orthorhombic Ti2ZrO were determined to be [0001](α-Ti)//[110](Ti2ZrO) and (10 (1) over bar0)(α-Ti)//(1 (1) over bar0)Ti2ZrO; meanwhile, those between the α-Ti and the spherical hexagonal Ti2ZrO were [0001](α-Ti)//[0001](Ti2ZrO) and (10 (1) over bar0)(α-Ti)//(10 (1) over bar0)(Ti2ZrO).
Individual and combined toxicity of nitriles and aldehydes to Raphidocelis subcapitata
(2005-05-01)
Chen, CY
;
Chen, SL
;
Christensen, ER
;
環境工程研究所
;
Institute of Environmental Engineering
A closed- system algal toxicity test with no headspace was applied to evaluate the toxicity of I I aldehydes and two nitrites to Raphidocelis subcapitata. Algal growth rate and dissolved oxygen (DO) production were used as the test endpoints. Compared to literature data, our test results based on the endpoint of DO production is 2.5 to 257 times more sensitive than the conventional algal batch tests. In addition, our analyses show that different relative toxicity relationships may be observed when different test methods or different endpoints are applied. The test alga was found to be quite sensitive to aldehydes, and a quantitative structure- activity relationship (QSAR) relationship was established based on the n-octanol/water partition coefficient (log K,,.). This study also evaluated the combined effects of aldehydes and nitriles. Four synergistic joint actions related to majononitrile were identified. On the other hand, most of the combined effects between aldehydes and acetonitrile were antagonistic. In general, we find that greater-than-additive effects mainly are associated with toxicants displaying flat dose-response curves, and less-than-additive effects may be related to certain steep-slope chemicals. Model analyses show that the above mixture toxicity behavior may be due to response addition or response multiplication joint action modes.
Freezing phase scheme for fast adaptive control and its application to characterization of femtosecond coherent optical pulses reflected from semiconductor saturable absorber mirrors
(2005-05-01)
Chen, MC
;
Huang, LY
;
Yang, QT
;
Pan, CL
;
光電工程學系
herent control with a femtosecond pulse shaper. The operational principle is based on a concept that the highest peak intensity will correspond to a frozen phase state of all spectral components involved in a coherent optical pulse. Our experimental and theoretical results reveal this new scheme to be fast and immune to the noise and laser power fluctuation. The freezing phase method has been used to investigate three types of semiconductor saturable absorber Bragg reflector (SBR). The optical pulses reflected from the SBR can be distorted in the spectral phase by a minor structural change of the SBR devices and can be clearly resolved with our method. The technique is useful for a variety of applications that require complete-field characterization and adaptive coherent control on the same setup. © 2005 Optical Society of America.
Wafer bonding for high-brightness light-emitting diodes via indium tin oxide intermediate layers
(2005-05-01)
Liu, PC
;
Hou, CY
;
Wu, YCS
;
材料科學與工程學系
;
Department of Materials Science and Engineering
A direct wafer-bonding technique has been used to fabricate high-brightness light emitting diodes (LEDs). However, bonding processes were usually performed at elevated temperatures, possibly causing degradation in the quality of the LED structure. In addition to this, misorientation between the two bonded wafers may have caused defects between the wafers. In this study, these two problems were solved by bonding the InGaP/GaAs and GaAs wafers with an indium tin oxide (ITO) polycrystalline film at temperatures below 650 degrees C. It was found that the bonding occurred mainly through the In transport from the InGaP to ITO, and that the electrical resistance decreased with the bonding temperature. (c) 2004 Elsevier B.V. All rights reserved.
Introduction to the special issue on integrated multimedia platforms
(2005-05-01)
Chiang, TH
;
Mattavelli, M
;
Turney, RD
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
利用控制偏振逐段曝照方法製作複雜的光纖光柵結構
(2005-05-01)
莊凱評
;
許立根
;
蔡孟璋
;
賴杰
本發明係提出一製造複雜光纖光柵曝照系統及方法，係於相位光罩製程或雙光束干涉製程中，加入一可旋轉之1／2波片以及一偏振分光稜鏡來完成，並將感光性光線放置於相對位移可以準確控制至奈米等級之位移平台上，藉此組合可以達到任意相位和折射率變化之複雜光纖光柵結構之製作。本發明之特點在於整個曝照過程只需一次連續移動即可完成，並且在完成複雜折射率變化之控制上更為準確及穩定。
Dynamics and thermal instability of magnetic flux in type-II superconductors
(2005-05-01)
Shapiro, BY
;
Shapiro, I
;
Rosenstein, B
;
Bass, F
;
電子物理學系
In recent experiments, trapped magnetic flux is initially generated by abrupt laser heating of a strip of a type-II superconducting film subjected to a weak magnetic field. We study herein the nonequilibrium penetration of the flux into the Meissner state area. Effects of the heal dissipation and transport on the motion and stability of the interface between the magnetic flux and flux-free domains are considered. It is shown that the magnetic induction and the temperature have the form of a shock wave moving with constant velocity as large as that corresponding to the depairing current. In the vicinity of the front, superconductivity is suppressed by strong screening currents. The front velocity is determined by the Joule heat caused by the electric current in the normal domain at the flux front. The stability of the shock wave solution is investigated both analytically and numerically. For sufficiently small heat diffusion constant a finger shaped thermal instability is found.
Reassessment of morphological characteristics in freshwater eels (genus Anguilla, Anguillidae) shows congruence with molecular phylogeny estimates
(2005-05-01)
Lin, YS
;
Tzeng, CS
;
Hwang, JK
;
生物科技學系
;
Department of Biological Science and Technology
The morphology-based phylogeny of freshwater eels, proposed by V. Ege in 1939, has been accepted as the basis of eel classification since that time. However, this has been called into question by recent molecular studies. Most of the morphological characteristics recognized by Ege are morphometric. Since methods for the application of morphometric data to phylogeny construction have not been fully established, it is unclear whether the observed discrepancies between morphological and molecular data arise from intrinsic differences or from flawed analyses. Here, we have used two methods to assemble evolutionary trees from distance matrices constructed according to Ege's data, the neighbor-joining (NJ) method and the minimum network (MinNet) method; the latter is based on an evolutionary algorithm. After reanalysing Ege's morphological data, we found that both methods gave results consistent with those based on molecular data, although not with Ege's original classification. Therefore, we speculate that some morphological features Ege used to subdivide the eel groups may not be synapomorphic as he proposed, but symplesiomorphic or convergent . The method developed here may prove useful for constructing phylogeny for taxon groups where only continuous morphometric characteristics are recognized, such as the freshwater eels.
Hybrid three-stage C- plus L-band optical fiber amplifier in cascade configuration
(2005-05-01)
Yeh, CH
;
Lai, KH
;
Lee, CC
;
Chi, S
;
光電工程學系
A hybrid C- plus L-band fiber amplifier module with three amplifier stages, which provides an operation range of 1540 to 1600 nm, is proposed and experimentally demonstrated. The proposed amplifier consists of two erbium-doped fiber amplifier (EDFAs) and a semiconductor optical amplifier (SOA) in cascade. Compared with a traditional L-band EDFA having longer EDF length, this amplifier can reduce the total EDF length to 44 m. As a result, 41.5 dB gain and a 3.7-dB noise figure are achieved at 1562 nm over the bandwidth of 1540 to 1600 nm, while the input signal power is -30 dBm. In addition, the behavior and performance of the proposed gain-clamping amplifier module over the C-plus L-band is investigated experimentally under different operation conditions. (c) 2005 Society of Photo-Optical Instrumentation Engineers.
一種感光性光纖之曝照系統及方法
(2005-05-01)
莊凱評
;
許立根
;
蔡孟璋
;
賴杰
本發明係提出一種僅需旋轉一旋轉反射鏡即可達微調干涉角度目的之雙光束干涉曝照系統。本發明之曝照系統將經旋轉反射鏡反射並經分光後之兩分光束中之任一組分光束之光程中置入一可旋轉之1／2波長偏振片，再將感光性光纖置放於一相對位移可準確控制至奈米等級的移動平台上，之後僅需在逐段曝照的過程中，將不同的相對位置配合旋轉偏振片於不同角度，即可達到一次連續曝照可至做出平均折射率平坦化的光纖光柵，此外，更可藉由旋轉對換1／2波長偏振片快慢軸的方式，來製作具180°相位改變之相位移光纖光柵。
The long length DHT design with a new hardware efficient distributed arithmetic approach and cyclic preserving partitioning
(2005-05-01)
Chen, HC
;
Chang, TS
;
Guo, JI
;
Jen, CW
;
電子工程學系及電子研究所
This paper presents a long length discrete Hartley transform (DHT) design with a new hardware efficient distributed arithmetic (DA) approach. The new DA design approach not only explores the constant property of coefficients as the conventional DA, but also exploits its cyclic property. To efficiently apply this approach to long length DHT, we first decompose the long length DHT algorithm to short ones using the prime factor algorithm (PFA), and further reformulate it by using Agarwal-Cooley algorithm such that all the partitioned short DHT still consists of the cyclic property. Besides, we also exploit the scheme of computation sharing on the content of ROM to reduce the hardware cost with the tradeoff in slowing down the computing speeds. Comparing with the existing designs shows that the proposed design can reduce the area-delay product from 52% to 91% according to a 0.35 mu m CMOS cell library.
A linear programming approach for identifying a consensus sequence on DNA sequences
(2005-05-01)
Li, HL
;
Fu, CJ
;
資訊管理與財務金融系註：原資管所+財金所
;
Department of Information Management and Finance
Motivation: Maximum-likelihood methods for solving the consensus sequence identification (CSI) problem on DNA sequences may only find a local optimum rather than the global optimum. Additionally, such methods do not allow logical constraints to be imposed on their models. This study develops a linear programming technique to solve CSI problems by finding an optimum consensus sequence. This method is computationally more efficient and is guaranteed to reach the global optimum. The developed method can also be extended to treat more complicated CSI problems with ambiguous conserved patterns. Results: A CSI problem is first formulated as a non-linear mixed 0-1 optimization program, which is then converted into a linear mixed 0-1 program. The proposed method provides the following advantages over maximum-likelihood methods: (1) It is guaranteed to find the global optimum. (2) It can embed various logical constraints into the corresponding model. (3) It is applicable to problems with many long sequences. (4) It can find the second and the third best solutions. An extension of the proposed linear mixed 0-1 program is also designed to solve CSI problems with an unknown spacer length between conserved regions. Two examples of searching for CRP-binding sites and for FNR-binding sites in the Escherichia coli genome are used to illustrate and test the proposed method.