Browsing by Issue Date, starting with "2006-04-01"

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MBE growth and structural and magnetic properties of (In1-gamma Al gamma)(1-x)MnxAs-diluted magnetic semiconductors
(2006-04-01)
Lee, WN
;
Chen, YF
;
Huang, JH
;
Guo, XJ
;
Kuo, CT
A series of quaternary-diluted magnetic semiconductors, (In1-y,Al-y)(1-x)MnxAs, have been successfully grown on InP substrates by low-temperature molecular beam epitaxy. The (ln(0.52)Al(0.48))(1-x)MnxAs with x <= 0.11 were grown on a nearly lattice-matched In0.52Al0.48As buffer, while the (In1-y,Al-y)(1-x)MnxAs with a higher Mn content of 0.11 < x <= 0.18 were grown on a graded 3-layer In,-,,Al-y 'As buffer structure. The results of transmission electron microscopy and double-crystal X-ray diffraction reveal that all (In1-yAly)(1-x),Mn,As epilayers are single crystal with zincblende structure, and the lattice constant increases with increasing the Mn content. The magnetic measurements show that the (In1-y,Al-y)(1-x)MnxAs semiconductors exhibit a paramagnetic-like state for x <= 0.05 while a ferromagnetic state for x >= 0.05, and the Curie temperature of ferromagnetic (In1-yAly)(1-x) MnxAs increases with increasing Mn content. (c) 2006 Elsevier B.V. All rights reserved.
Expression and purification of human placenta lactogen in Escherichia coli
(2006-04-01)
Lan, PC
;
Tseng, CF
;
Lin, MC
;
Chang, CA
;
生物科技學系
There are many growth factors secreted by placenta including growth hormone, placenta lactogen (PL), prolactin, follicle stimulating hormone, luteinizing hormone, thyroid stimulating hormone, and chorionic gonadotropin. For a systematic study of how these growth factors work together to result in the various biological functions and future clinical applications, it is needed to produce enough quantities of each protein. In this paper, we report the cloning of human PL (hPL) and expression by Escherichia coli (E coli). Four kinds of expression vectors containing the hPL gene were transformed into several kinds of suitable host strains and grown at 37 and/or 30 degrees C. Determination of the yield of recombinant hPL by SDS-PAGE reveals that among the various conditions, pQE30-PL in E. coli strain M15[pREP4] expressed the largest amount of recombinant hPL at 37 degrees C. However, the expressed recombinant hPL was accumulated in inclusion body forms. The inclusion bodies were solubilized in 8 M urea and purified by a His(6) tagged affinity column under denaturing condition and the final yield of hPL was determined to be 48 mg/L. Intra-chain disulfide bonds could be formed either by oxidation in the refolding buffer or by air oxidation in the presence of urea. The biological activity was examined by the fact that hPL could stimulate erythroid maturation by the formation of hemoglobin in K-562 cells in the presence of erythropoietin. Initial optimization studies resulted in the production of 282.4 mg/L of hPL. (c) 2005 Elsevier Inc. All rights reserved.
A background timing-skew calibration technique for time-interleaved analog-to-digital converters
(2006-04-01)
Wang, CY
;
Wu, JT
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
This paper presents a background timing-skew calibration technique for time-interleaved analog-to-digital converters (ADCs). The timing skew between any two adjacent analog-digital (AID) channels is detected by counting the number of zero crossings of the ADCs input while randomly alternating their sampling sequence. Digitally controlled delay units are adjusted to minimize the timing skews among the AID channels caused by the mismatches among the clock routes. The calibration behaviors, including converging speed and timing jitter, are theoretically analyzed and verified with simulations. A 6-bit 16-channel ADC is used as an example.
Ritter reaction of 1-aryl-1-fluoro-2-haloethanes
(2006-04-01)
Ho, TL
;
Chein, RJ
;
應用化學系
;
Department of Applied Chemistry
Fluorinated phenethyl bromides 1, 2, and 3, prove to be totally inert under Ritter reaction conditions in the presence of either SnCl4 or AgNO3, due to the strong deactivation by the gem-difluoro unit. Subjecting 2-bromo-1-fluoro-1-phenylethane to SnCl4 in MeCN at elevated temperatures led to formation of 2-methyl-4-phenyl-4,5-dihydrooxazole.
Topological horseshoes for perturbations of singular difference equations
(2006-04-01)
Li, MC
;
Malkin, M
;
應用數學系
;
Department of Applied Mathematics
In this paper, we Study solutions of difference equations Phi(lambda)(y(n), y(n+1),...,y(n+m)) = 0, n is an element of Z, of order in with parameter lambda, and consider the case when Phi(lambda) has a singular limit depending on a single variable as lambda -> lambda(0), i.e. Phi(lambda 0)(y(0),...,y(m)) = phi(y(N)), where N is an integer with 0 <= N <= m and phi is a function. We prove that if phi has k simple zeros then for lambda close enough to lambda(0), the difference equation has a k-horseshoe among its solutions, that is, the dynamics is conjugate to the full shift with k symbols. Moreover, we show that these horseshoes change continuously in the uniform topology as lambda varies. As applications of these results, we establish the horseshoe structure in families of generalized Henon-like maps and of Arneodo-Coullet-Tresser maps near their anti-integrable limits as well as in steady states for certain lattice models.
Multiple-objective planning for a production and distribution model of the supply chain: Case of a bicycle manufacturer
(2006-04-01)
Tzeng, GH
;
Tang, TI
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Huang, YM
;
Chang, ML
;
科技管理研究所
The bicycle industry is one of the most competitive industries in Taiwan. To construct multi-objective production and distribution models tor supply chain, following five methods are compared and discussed: (i) Multi-objective compromise programming; (ii) Fuzzy multi-objective programming (iii) Weighted multi-objective programming; (iv) Weighted fuzzy multi-objective programming; and (v) Two-phase fuzzy multi- objective programming. The weighted multi-objective model has been found better for considering the maximum profit for enterprises and the maximum quality for customer service. After raising the per-unit production cost in production processes, it was observed that the total profit would decrease in real empirical study. In addition, if the unit inventory cost increases due to improving the customer service level, then the total profit might increase, but not significantly.
A modified HICUM model for GaInP/GaAs HBT devices
(2006-04-01)
Tseng, SC
;
Meng, CC
;
Chen, WY
;
Su, JY
;
電信工程研究所
A compact physics-based transit-time model is established for the GaInP/GaAs HBT device. The VBIC model fails to describe the transit-time frequency versus bias (I-C, V-CE), especially at low- and medium-current regimes. Starting with the HICUM model, we introduce a new time constant to describe the transit-time frequency versus bias (I-C, V-CE) more precisely. This model has obvious advantages over the VBIC model for showing the relation oj'f, versus bias (I-C, V-CE) in the low and medium current regimes for GaInP/GaAs HBT devices. (c) 2006 Wiley Periodicals, Inc.
Low-temperature growth mechanism of SW-NTs networks by buffer layer-assisted MPCVD
(2006-04-01)
Wang, W. H.
;
Peng, Y. R.
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Chuang, P. K.
;
Kuo, C. T.
;
材料科學與工程學系
We present the microstructures and growth mechanism of networks of single-walled carbon nanotubes (SWNTs) fabricated by buffer layer-assisted microwave plasma chemical vapor deposition (MPCVD) at relatively low temperatures. The morphologies and bonding structures of carbon nanostructures were characterized by field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), and Raman Spectroscopy. Additionally, the surface roughness of buffer layer and its bonding structures with catalyst atom are analyzed by atomic force microscope (AFM) and X-ray photoelectron spectroscopy (XPS), respectively. Analytical results demonstrate that networks of CNTs are formed by bundles or individual SWNTs. We suggest that the formation of SWNTs networks at low temperature may follow the root-growth mechanism. The differences comparing with previous growth mechanism are that the nuclei formation resulted from the rough surface of the buffer layer, and dissolution of carbon in catalyst will be enhanced due to the surface diffusion of the buffer layer. These unique effects from the buffer layer can provide favorable conditions to grow SWNTs at relatively low process temperatures. (c) 2005 Elsevier B.V. All rights reserved.
Snug-Vegas and Snug-Reno: efficient mechanisms for performance improvement of TCP over heterogeneous networks
(2006-04-01)
Ho, CY
;
Chen, YC
;
資訊工程學系
;
Department of Computer Science
Improving the performance of the traditional TCP in wireless IP communications has been an active research area. The significant cause of packet losses in such heterogenous networks is no longer limited to network congestion. The performance degradation of TCP in wireless and wired-wireless hybrid networks is mainly due to its lack of ability to differentiate the packet losses caused by network congestions from the losses caused by wireless link errors. New variants of TCP Vegas and TCP Reno named Snug-Vegas and Snug-Reno, respectively, are proposed. By using random-loss indications marked by base stations, Snug-Vegas and Snug-Reno may detect random packet losses precisely. Through the packet loss differentiation, Snug-Vegas and Snug-Reno react appropriately to the losses, and based on the simulation results, it is seen that the throughput of connection over heterogeneous networks can be significantly improved.
Improvement of electrical characteristics for fluorine-ion-implanted poly-Si TFTs using ELC
(2006-04-01)
Tu, CH
;
Chang, TC
;
Liu, PT
;
Yang, CY
;
Liu, HC
The fluorine ion implantation applied to the polycrystalline silicon thin-film transistors (poly-Si TFTs) is investigated in this letter. Experimental results have shown that fluorine ion implantation effectively minimized the trap state density, leading to superior electrical characteristics such as high field-effect mobility, low threshold voltage, and high ON/OFF current ratio. Furthermore, the fluorine ions tended to segregate at the interface between the gate oxide and poly-Si layers during the excimer laser annealing, even without the extra deposition of pad oxide on the poly-Si film. The presence of fluorine obviously enhanced electrical reliability of poly-Si TFTs.
Spectroscopic study of bio-functionalized nanodiamonds
(2006-04-01)
Chung, P. -H.
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Perevedentseva, E.
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Tu, J. -S.
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Chang, C. C.
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Cheng, C. -L.
Nano-scale materials with attached biomolecules on the surface can be used as bioprobes in cell and tissue analysis. The conjugation of these nanoparticles with biomolecules is one of the key steps in the development of bioprobes. In this work nanometer-sized diamonds (5 and 100 nm) are functionalized and conjugated with protein lysozyme via physical adsorption. The process of creating functional groups on the nanodiamond surface is studied using Fourier Transform Infrared-spectroscopy (FTIR). The conjugation of nanodiamonds with biontolecules and nanodiamond-biomolecule interaction are analyzed with UV/VIS and FTIR spectroscopy. (c) 2005 Elsevier B.V. All rights reserved.
A low power turbo/Viterbi decoder for 3GPP2 applications
(2006-04-01)
Lin, CC
;
Shih, YH
;
Chang, HC
;
Lee, CY
;
電子工程學系及電子研究所
This paper presents a channel decoder that completes both turbo and Viterbi decodings, which are pervasive in many wireless communication systems, especially those that require very low signal-to-noise ratios. The trellis decoding algorithm merges them with less redundancy. However, the implementation is still challenging due to the power consumption in wearable devices. This research investigates an optimized memory scheme and rescheduled data flow to reduce power consumption and chip area. The memory access is reduced by buffering the input symbols, and the area is reduced by reducing the embedded interleaver memory. A test chip is fabricated in a 1.8 V 0.18-mu m standard CMOS technology and verified to provide 4.25-Mb/s turbo decoding and 5.26-Mb/s Viterbi decoding. The measured power dissipation is 83 mW, while decoding a 3.1 Mb/s turbo encoded data stream with six iterations for each block. The power consumption in Viterbi decoding is 25.1 mW in the 1-Mb/s data rate. The measurement shows the power dissipation is 83 mW for the turbo decoding with six iterations at 3.1 Mb/s, and 25.1 mW for the Viterbi decoding at 1 Mb/s.
Fabricating and characterizing oblique polymer structures by electron beam writing on resist-coated SiO2 wafers
(2006-04-01)
Ko, FH
;
Chen, JK
;
Chang, FC
;
材料科學與工程學系奈米科技碩博班
;
應用化學系
We have successfully fabricated SU-8 materials having oblique structures by a new electron beam technology.-We studied the contrast, sensitivity, etching, and thermal properties of SU-8, PMMA, and KrF resists to evaluate their suitability for the fabrication of oblique structures. Among these resists, SU-8 revealed the lowest contrast ratio, highest throughput, and best thermal stability, and so it became the candidate material for patterning the oblique structures. The technique we have developed involves five regional exposures of a thick SU-8 resist layer with various electron beam dosages. Furthermore, we discuss the surface morphology, reaction mechanism, and hydrophobicity after subjecting the SU-8 resist to a series of plasma treatments. The formation of surface nano-nodules during oxygen plasma treatment explains the surface hydrophobicity. We have carefully evaluated the effects of the electron beam writing dose and the design of the exposure area with respect to the inclined angle of the fabricated structure. (c) 2006 Elsevier B.V. All rights reserved.
Organic selective-area patterning method for microlens array fabrication
(2006-04-01)
Huang, WK
;
Ko, CJ
;
Chen, FC
;
光電工程學系
;
顯示科技研究所
Refractive microlens arrays (MLAs) are widely used in many electro-optical devices due to their high performance and low optical loss. To fabricate a microlens array effectively, we have proposed a novel fabrication method based on a selective-area patterning method. The surface properties of glass substrates were defined as either hydrophilic or hydrophobic regions by microcontact printing of self-assembled monolayers (SAMs). Consequently, the microlens arrays were self-organized on the hydrophilic regions after the lens materials were nozzle-spread followed by UV curing. As a result, we have demonstrated microlenses with 50, 75, and 100 Pm footprints, and f numbers as low as 5.4. The focused spot size of the 50 mu m lens was 9.82 mu m, which is near the diffraction limit. The optical measurement shows excellent light collecting efficiency of a microlens array, which is suitable for many electro-optical applications. Furthermore, all fabrication steps can be accomplished in ambient environment and at room temperature. It is anticipated that the present proposed method has great potential for mass production. (c) 2006 Elsevier B.V. All rights reserved.
Characterization of imprinting polymeric temperature variation with fluorescent Rhodamine B molecule
(2006-04-01)
Ko, FH
;
Weng, LY
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Ko, CJ
;
Chu, TC
;
材料科學與工程學系奈米科技碩博班
The method to measure the imprint temperature variation of resist film with fluorescence probe technique was established. The maximal Rhodamine B concentration was 8 X 10(-4) M to achieve higher sensitivity and avoid precipitation problem. The temperature effect was a critical parameter on the temperature sensing, while imprinting pressure was not. The fluorescence intensity of Rhodamine B linearly decayed with time at various temperatures due to the formation of lactone-containing molecule during thermal stressing. The usual imprint time of less than 20 min was not affected by the signal decay effect due to limited percentage of signal variation during 100200 degrees C. The technique based on fluorescence probe method was successfully applied to measure the resist temperature variation of the imprint on the resist film of 6-in. wafer. (c) 2006 Elsevier B.V. All rights reserved.
Variables sampling plans with PPM fraction of defectives and process loss consideration
(2006-04-01)
Pearn, WL
;
Wu, CW
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
Acceptance sampling plans provide the vendor and the buyer decision rules for lot sentencing to meet their product quality needs. A problem the quality practitioners have to deal with is the determination of the critical acceptance values and inspection sample sizes that provide the desired levels of protection to both vendors and buyers. As today's modern quality improvement philosophy, reduction of variation from the target value is the guiding principle as well as reducing the fraction of defectives. The C-pm index adopts the concept of product loss, which distinguishes the product quality by setting increased penalty to products deviating from the target. In this paper, a variables sampling plan based on Cpm index is proposed to handle processes requiring very low parts per million (PPM) fraction of defectives with process loss consideration. We develop an effective method for obtaining the required sample sizes n and the critical acceptance value C-0 by solving simultaneously two nonlinear equations. Based on the designed sampling plan, the practitioners can determine the number of production items to be sampled for inspection and the corresponding critical acceptance value for lot sentencing.
轉上市能增加媒體能見度嗎？
(2006-04-01)
洪榮耀
;
馬黛
;
Jung-Yao Hung
;
Tai Ma
;
Institute of Business and Management
本文是國內首篇研究自中華民國櫃檯買賣中心移轉至台灣證券交易所之公司其媒體能見度變化，並以此變化來瞭解轉上市是否能增加公司能見度。我們針對1999，2000，2001及2003年台灣證券市場轉上市公司，以公司名稱被刊於平面媒體之次數做為公司媒體能見度指標，進行公司媒體能見度提升之相關分析。實證結果有三個主要發現，(1)公司藉由轉上市可提升其媒體能見度。(2)上櫃時間長短及資本額大小與能見度效果互為反向。(3)台灣證券市場轉上市公司之媒體能見度提升是與轉上市有關，而非來自盈餘成長或市值成長。本文結果可與Baker and Pettit (1982), Baker and Johnson (1990)提出之管理者以能見度作為上市動機相互對應，並確認了Arbel and Strebel (1982，1983)，Carvel and Strebel (1987), Christie and Huang (1994)及Baker et al. (1999b)之較受忽略之公司轉上市效益較大之主張，但與Dharan and Ikenberry (1995)，Baker et al (1998)及Baker et al. (1999a)指稱之盈餘成長或市值成長能增加公司能見度並不相同。
Agility index in the supply chain
(2006-04-01)
Lin, CT
;
Chiu, H
;
Chu, PY
;
管理科學系
;
Department of Management Science
To achieve a competitive edge in the rapidly changing business environment, companies must align with suppliers and customers to streamline operations, as well as working together to achieve a level of agility beyond individual companies. Consequently, agile supply chains are the dominant competitive vehicles. Embracing agile supply chain requires asking some important questions, namely: what exactly is agility and how can it be measured? Moreover, how can agility be effectively achieved and enhanced? Due to the ambiguity of agility assessment, most measures are described subjectively using linguistic terms. Thus, this study develops a fuzzy agility index (FAI) based on agility providers using fuzzy logic. The FAI comprises attribute' ratings and corresponding weights, and is aggregated by a fuzzy weighted average. To illustrate the efficacy of the method, this study also evaluates the supply chain agility of a Taiwanese company. This evaluation demonstrates that the method can provide analysts with more informative and reliable information for decision. (c) 2004 Elsevier B.V. All rights reserved.
Study of InGaN multiple quantum dots by metal organic chemical vapor deposition
(2006-04-01)
Wang, TC
;
Kuo, HC
;
Lu, TC
;
Tsai, CE
;
Tsai, MY
We reports a study of InGaN Multiple quantum dot layers. Using the in-situ SiNx treatment process, InGaN multiple quantum dot layers were successfully developed. The InGaN multiple quantum dot layers were constructed with SiNx dot mask layers, InGaN dot layers, and GaN cap layers on a 2-mu m-thick GaN underlying layer on a sapphire substrate. Optical properties including room temperature photoluminescence (PL), temperature dependent PL, and low power power-dependent PL were examined and discussed. The structure was also analyzed by transmission electron microscopy (TEM) and energy dispersive X-ray (EDX) line scan.
Improved reliability of HfO2/SiON gate stack by fluorine incorporation
(2006-04-01)
Lu, WT
;
Chiein, CH
;
Lan, WT
;
Lee, TC
;
Lehnen, P
Effects of fluorine (F) incorporation on the reliabilities of pMOSFETs with HfO2/SiON gate stacks have been studied. In this letter, fluorine was incorporated during the source/drain implant step and was diffused into the gate stacks during subsequent dopant activation. The authors found that F introduction only negligibly affects the fundamental electrical properties of the transistors, such as threshold voltage V-th, subthreshold swing, gate leakage current, and equivalent oxide thickness. In contrast, reduced generation rates in interface states and charge trapping under constant voltage stress and bias temperature stress were observed for the fluorine-incorporated split. Moreover, the authors demonstrated for the first time that F incorporation could strengthen the immunity against plasma charging damage.