Browsing by Issue Date, starting with "2003-10-15"

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Resonant hydrogenic impurity states and 1s-2p(0) transitions in coupled double quantum wells
(2003-10-15)
Yen, ST
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Calculations of the 1s and resonant 2p(0) states of a shallow donor in double-quantum-well structures are performed. The variational method is used to calculate the localized part of the impurity states, taking into account the effect of intersubband mixing. The resonance coupling of the 2p(0) state with the first subband is then dealt with using the Green function technique. The results show that for an asymmetric double-quantum-well structure the 1s state has a maximum binding energy as the donor is around the center of the wider well while the 2p(0) state has in general a maximum binding energy as the donor is in the narrower well. The resonant coupling of the 2p(0) state is stronger for the structures with a stronger intersubband mixing, where the 2p(0) energy level is closer to the first subband bottom. The resonance-induced broadening of the 2p(0) state can be as large as 6 meV, corresponding to a lifetime of similar to0.1 ps. The resonance in general causes a negligibly small blueshift but can give a redshift of the order of 1 meV when the resonance is strong. A phase transition of the 2p(0) state can occur from the resonant nature to the bound nature by modulation of the interwell coupling. The 1s-2p(0) transition energy is also calculated. The possibility of population inversion between the 1s and 2p(0) states is discussed.
Improved technique for measuring refractive index and thickness of a transparent plate
(2003-10-15)
Jian, ZC
;
Hsu, CC
;
Su, DC
;
光電工程學系
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Department of Photonics
The phase difference between s- and p-polarizations of a circularly polarized heterodyne light beam reflected from a transparent plate is measured. The measured data is substituted into the specially derived equations and the refractive index can be calculated. Next, the variations of phase difference between s- and p-polarizations due to the wavelength shift and the extraction of the plate in a modified Michelson interferometer are measured. Then, its thickness can be calculated based on the measured value of refractive index, the variations of phase difference, and the specified value of wavelength shift. (C) 2003 Elsevier B.V. All rights reserved.
Monotone iterative methods for the adaptive finite element solution of semiconductor equations
(2003-10-15)
Chen, RC
;
Liu, JL
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應用數學系
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Department of Applied Mathematics
Picard, Gauss-Seidel, and Jacobi monotone iterative methods are presented and analyzed for the adaptive finite element solution of semiconductor equations in terms of the Slotboom variables. The adaptive meshes are generated by the 1-irregular mesh refinement scheme. Based on these unstructured meshes and a corresponding modification of the Scharfetter-Gummel discretization scheme, it is shown that the resulting finite element stiffness matrix is an M-matrix which together with the Shockley-Read-Hall model for the generation-recombination rate leads to an existence-uniqueness-comparison theorem with simple upper and lower solutions as initial iterates. Numerical results of simulations on a MOSFET device model are given to illustrate the accuracy and efficiency of the adaptive and monotone properties of the present methods. (C) 2003 Elsevier B.V. All rights reserved.
Lower confidence bounds with sample size information for C-pm applied to production yield assurance
(2003-10-15)
Pearn, WL
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Shu, MH
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工業工程與管理學系
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Department of Industrial Engineering and Management
The process capability index C-pm, sometimes called the Taguchi index, has been proposed to the manufacturing industry as providing numerical measures on process performance. A lower confidence bound estimates the minimum process capability, conveying critical information regarding product quality, which is essential to quality assurance. The sample size determination is directly related to the cost of the data collection plan. The purpose of this paper is to provide explicit formulas with efficient algorithms to obtain the lower confidence bounds and sample sizes required for specified precision of the estimation on C-pm using the maximum likelihood estimator (MLE) of C-pm. We also provide tables for the engineers/practitioners to use for their in-plant applications. A real-world example taken from a microelectronics manufacturing process is investigated to illustrate the applicability of the proposed approach. The implementation of existing statistical theory for capability assessment bridges the gap between the theoretical development and factory applications.
A fuzzy-based customer classification method for demand-responsive logistical distribution operations
(2003-10-16)
Hu, TL
;
Sheu, JB
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運輸與物流管理系註：原交通所+運管所
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Department of Transportation and Logistics Management
In some cases, customer classification is important for the development of advanced logistical distribution strategies in response to the growing complexity in business logistical markets. This paper presents a new approach that can be employed to cluster customers before executing fleet routing in logistical operations. The proposed approach is developed on the basis of fuzzy clustering techniques, and involves three sequential mechanisms including: (1) binary transformation, (2) generation of a fuzzy correlation matrix, and (3) customer clustering. Such a customer clustering method should be performed prior to vehicle dispatching and routing in the process of goods distribution. The proposed methodology clusters customers on the basis of their demand attributes, rather than the static geographic property which is considered extensively in most published vehicle routing algorithms. In addition to methodology development, a case study was conducted to demonstrate the potential advantages of the proposed fuzzy clustering based method. It is expected that this study can stimulate more research on time-based logistics control and management. (C) 2002 Elsevier B.V. All rights reserved.
High-speed characteristics of large-area single-transverse-mode vertical-cavity surface-emitting lasers
(2003-10-16)
Hsueh, TH
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Kuo, HC
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Lai, FI
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Laih, LH
;
Wang, SC
The single transverse mode operation of VCSELs with low threshold current (I-th) of 1.5 mA, slope efficiencies about 0.35 W/A, high optical output power of 3.8 mW and speed performance of 10 Gbit/s is reported. The laser has continuous-wave operation and employs oxygen implantation, MOCVD regrowth and selective oxidation on semi-insulating GaAs substrate.
Effect of the Ca content on the electronic structure of Pb1-xCaxTiO3 perovskites
(2003-10-20)
Jan, JC
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Kumar, KPK
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Chiou, JW
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Tsai, HM
;
Shih, HL
This study performs O K- and Ti L-3,L-2-edge x-ray absorption near-edge structure (XANES) measurements and first-principles pseudopotential calculations for the electronic structures of ABO(3)-type Pb1-xCaxTiO3 (x=0-1) perovskites. The features in the O K-edge XANES spectra are found to be contributed primarily by hybridization between O 2p and Ti 3d, Pb 6p, and Ca 3d orbitals. The O K-edge XANES spectra reveal that partial substitution of A cations, Pb, by Ca not only decreases O 2p-Pb 6p but also O 2p-Ti 3d hybridization. The Ti L-3,L-2-edge measurements find that the off-center displacement of Ti, and hence, ferroelectricity persist up to a Ca concentration between 0.3 and 0.4. (C) 2003 American Institute of Physics.
Morphological transformation of PS-b-PEO diblock copolymer by selectively dispersed colloidal CdS quantum dots
(2003-10-21)
Yeh, SW
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Wei, KH
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Sun, YS
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Jeng, US
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Liang, KS
Power-saving protocols for IEEE 802.11-based multi-hop ad hoc networks
(2003-10-22)
Tseng, YC
;
Hsu, CS
;
Hsieh, TY
;
資訊工程學系
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Department of Computer Science
Power-saving is a critical issue for almost all kinds of portable devices. In this paper, we consider the design of power-saving protocols for mobile ad hoc networks (MANETs) that allow mobile hosts to switch to a low-power sleep mode. The MANETs being considered in this paper are characterized by unpredictable mobility, multi-hop communication, and no clock synchronization mechanism. In particular, the last characteristic would complicate the problem since a host has to predict when another host will wake up to receive packets. We propose three power management protocols, namely dominating-awake-interval, periodically-fully-awake-interval, and quorum-based protocols, which are directly applicable to IEEE 802.11-based MANETs. As far as we know, the power management problem for multi-hop MANETs has not been seriously addressed in the literature. Existing standards, such as IEEE 802.11, HIPERLAN, and bluetooth, all assume that the network is fully connected or there is a clock synchronization mechanism. Extensive simulation results are presented to verify the effectiveness of the proposed protocols. (C) 2003 Elsevier B.V. All rights reserved.
Scattering and guiding characteristics of waveguides with two-dimensionally periodic walls of finite thickness
(2003-10-23)
Hwang, RB
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Peng, ST
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友訊交大聯合研發中心
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D Link NCTU Joint Res Ctr
[1] Electromagnetic wave propagation along waveguides having two-dimensionally (2-D) periodic walls with finite thickness is formulated here as an exact boundary-value problem. The dispersion relation of such a class of waveguide is systematically analyzed in terms of both phase and attenuation constants. In addition, the contour map of field components and Poynting vector are also demonstrated in this paper to verify the guiding characteristics of such a class of waveguides. In particular, the strong couplings between an incident plane wave and waveguide modes phase-matching condition are carefully examined and are employed to identify the existence of waveguide modes.
Growth rate regulation of lac operon expression in Escherichia coli is cyclic AMP dependent
(2003-10-23)
Kuo, JT
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Chang, YJ
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Tseng, CP
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生物科技學系
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Department of Biological Science and Technology
In contrast to the ribosomal RNA gene expression increasing with growth rate, transcription of the lac operon is downregulated by cell growth rate. In continuous culture, growth rate regulation of lac promoter was independent of carbon substrate used and its location on the chromosome. Since the lac operon is activated by cyclic adenosine monophosphate (cAMP), which decreases with increasing cell growth rate, expression of plac-lacZ reporter fusion was analyzed in cya mutant under various growth conditions. The results demonstrated that expression of plac-lacZ in cya mutant was both lower and growth rate independent. In addition, ppGpp (guanosine tetraphosphate) was not involved in the mechanism of growth rate regulation of the lac promoter. Thus, the results of this study indicate that cAMP mediates the growth rate-dependent regulation of lac operon expression in Escherichia coli. (C) 2003 Published by Elsevier B.V. on behalf of the Federation of European Biochemical Societies.
Improvement of near-ultraviolet InGaN/GaN light-emitting diodes by inserting an in situ rough SiN(x) interlayer in n-GaN layers
(2003-10-27)
Tu, RC
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Chuo, CC
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Pan, SM
;
Fan, YM
;
Tsai, CE
Near-ultraviolet 400-nm InGaN/GaN multiple-quantum-well light-emitting diodes (LEDs) with and without an in situ rough SiN(x) interlayer inserted into the n-GaN underlying layer were grown on c-face sapphire substrates by metalorganic vapor phase epitaxy. Inserting the SiN(x) interlayer into the n-GaN underlying layer slightly reduced leakage current induced by reducing the defect density. Additionally, an enhancement of light extraction for the LED with a SiN(x) interlayer is expected because of the increased intensity of light scattered on the SiN(x) nanomask, changing the directions of propagation of light. Consequently, the emission efficiency of an LED with an in situ rough SiN(x) interlayer doubles that without a SiN(x) interlayer. (C) 2003 American Institute of Physics.
Improvement of near-ultraviolet InGaN/GaN light-emitting diodes by inserting an in situ rough SiNx interlayer in n-GaN layers
(2003-10-27)
Tu, RC
;
Chuo, CC
;
Pan, SM
;
Fan, YM
;
Tsai, CE
Near-ultraviolet 400-nm InGaN/GaN multiple-quantum-well light-emitting diodes (LEDs) with and without an in situ rough SiNx interlayer inserted into the n-GaN underlying layer were grown on c-face sapphire substrates by metalorganic vapor phase epitaxy. Inserting the SiNx interlayer into the n-GaN underlying layer slightly reduced leakage current induced by reducing the defect density. Additionally, an enhancement of light extraction for the LED with a SiNx interlayer is expected because of the increased intensity of light scattered on the SiNx nanomask, changing the directions of propagation of light. Consequently, the emission efficiency of an LED with an in situ rough SiNx interlayer doubles that without a SiNx interlayer. (C) 2003 American Institute of Physics.
Activation of the calcineurin-nuclear factor of activated T-cell signal transduction pathway in atrial fibrillation
(2003-10-28)
Lai, LP
;
Lin, CC
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Lin, JL
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Lin, CS
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生物科技學系
Planar mode converter used in printed microwave integrated circuits
(2003-10-28)
Tzuang
;
Ching-kuang
;
Lee
;
Cheng-jung
A planar mode converter includes a rectangular waveguide, a microstrip feed-in circuit, and a microstrip feed-out circuit. The rectangular waveguide is filled with dielectric layers and surrounded with metal materials. The lowermost dielectric layer has usually largest thickness and dielectric constant. Except for the lowermost dielectric layer, each of the dielectric layers has a rectangular aperture at its front-end and back-end, respectively. The microstrip feed-in circuit is constituted by first, second and third metal strips, and a feed-in metal ground plane. The first metal strip and the feed-in metal ground plane form a feed-in signal line. The first, second and third metal strips are adhered to the top surface of the lowermost dielectric layer, and the feed-in metal ground plane is adhered to the bottom surface of the lowermost dielectric layer. The microstrip feed-out circuit is constituted of fourth, fifth and sixth metal strips, and a feed-out metal ground plane. The sixth metal strip and the feed-out metal strip form a feed-out signal line.
Evolution of the yeast protein interaction network
(2003-10-28)
Qin, H
;
Lu, HHS
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Wu, WB
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Li, WH
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統計學研究所
To study the evolution of the yeast protein interaction network, we first classified yeast proteins by their evolutionary histories into isotemporal categories, then analyzed the interaction tendencies within and between the categories, and finally reconstructed the main growth path. We found that two proteins tend to interact with each other if they are in the same or similar categories, but tended to avoid each other otherwise, and that network evolution mirrors the universal tree of life. These observations suggest synergistic selection during network evolution and provide insights into the hierarchical modularity of cellular networks.
The electrochemical behavior of tin-doped indium oxide during reduction in 0.3 M hydrochloric acid
(2003-10-30)
Huang, CA
;
Li, KC
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Tu, GC
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Wang, WS
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材料科學與工程學系
The electrochemical behavior of tin-doped indium oxide (ITO) on SiO2 in 0.3 M HCl was studied using voltammetric scanning method. The result showed that an obvious reduction current peak occurred during the first cathodic potential scanning. The reduction reaction became less active after annealing ITO at 500 C for 1 h. The result was attributed to the replenishment of oxygen-deficient site, which acts as current carrier, by the annealing treatment. Many spherical In-Sn particles with sizes about 100-500 nm were formed on the ITO surface adjacent to the grain boundary when the reduction current took place. The In-Sn particles initiated preferentially on the ITO surface near grain boundaries attending the dissolution of ITO grain boundary. In the scanning period, after completion of the reduction current peak, reduction of hydrogen ions occurred in more negative potential region. A schematic illustration for the formation mechanism of the In-Sn reduction particle was postulated based on the metallographical and electrochemical results in this work. (C) 2003 Elsevier Ltd. All rights reserved.
金氧半場效電晶體之閘極結構
(2003-11-01)
崔秉鉞
;
黃誌鋒
本發明係提出一種新的合金系統，用以解決金氧半場效電晶體金屬閘極功函數的不適性，促使表面通道電晶體起始電壓係可有效降低，達到低工作電壓之要求，本合金系統以化學性質不活潑且熱穩定性極佳的鉑金屬(Pt)為主成分，加入不同比例之低功函數材料，例如：鉭(Ta)或鈦(Ti)，以達成調整功函數之目的。合金閘的製作方法可以是同時濺鍍(co-sputter)或是同時蒸鍍(co-evaporation)的物理氣象沉積方式，依所需之成分調整鉑靶及低功函數金屬靶之沉積速率，以合成適當的鉑合金，亦可以使用事先合成之合金靶，以單純物理性濺鍍方式製作。
Characterizing trench-gate power metal-oxide-semiconductor field effect transistor with multi-layer dielectrics at the trench bottom
(2003-11-01)
Lin, MJ
;
Liaw, CW
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Chang, FL
;
Cheng, HC
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電子工程學系及電子研究所
Power devices with a high switching speed and a low conduction resistance are crucially important in power conversion circuits. In this study, a trench-gate power metal-oxide-semiconductor field effect transistor (MOSFET) with a high-density cell design 20.6 Mcell/cm(2) was implemented for the first time using multilayer dielectrics with an oxide-nitride-oxide (ONO) structure at the bottom of the trench. The thick ONO dielectric layers at the bottom of the trench compensate for the increase in Miller capacitance per unit area as the cell density increases. The resulting device exhibits excellent characteristics of gate charge, switching power loss, gate oxide quality and practical process stability, superior to those of the conventional structure. An n-channel 25.8 V trench gate MOSFET with a specific on-resistance of 0.15 mOmegam(2), and R-ON x Q(GD) figure-of-merit 41 mOmega.nC is presented.
Special section on bioinformatics - Foreword
(2003-11-01)
Hwang, JK
;
Kao, MY
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Sun, CT
;
Hsu, WL
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生物科技學系