Browsing by Issue Date, starting with "2007-10-29"

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Highly efficient white organic light-emitting diodes with single small molecular emitting material
(2007-10-29)
Wang, Lei
;
Lin, Mei-Fang
;
Wong, Wai-Kwok
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Cheah, Kok-Wai
;
Tam, Hoi-Lam
We demonstrate a highly efficient white organic light emitting device with fluorescent small molecule 4,4'-bis(9-(1-naphthyl)anthracene-10-yl)biphenyl (BUBH-3). With a simple device architecture of indium tin oxide/tris 4,4',4'-tris-N-naphthyl-N-phenylamino-triphenylamine (60 nm)/N,N'-bis-(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine (10 nm)/BUBH-3 (45 nm)/Alq(3) (15 nm)/LiF (1 nm)/Al (150 nm), a white light with CIEx,y color of (0.31,0.36) was generated. The device achieved one of the best single-emitting-material electroluminescence performance of white organic light-emitting devices with efficiencies of 7.0 cd/A and 3.17 lm/W at 6.9 V. (C) 2007 American Institute of Physics.
Surface excitation parameter for electrons crossing the A1N surface
(2007-10-29)
Kwei, C. M.
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Tu, Y. H.
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Tung, C. J.
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
Fast electrons crossing a solid surface induce surface excitations. The total probability of such excitations for electrons moving outside the solid, i.e. in vacuum, is characterized by the surface excitation parameter (SEP). In the present work, the SEP was calculated for either incident or escaping electrons with normal or glancing crossing angles over the surface of aluminum nitride (AlN), a wide-band-gap semiconductor. These calculations were performed based on the dielectric response theory using the sum-rule-constrained extended Drude dielectric function with parameters obtained from a fit of this function to experimental optical data and electron energy-loss data. Dependences of the SEP on electron energy and crossing angle were analyzed. A simple formula was proposed for the fitting of SEP as a function of electron energy and crossing angle. (C) 2007 Elsevier Ltd. All rights reserved.
Dual-probe near-field fiber head with gap servo control for data storage applications
(2007-10-29)
Fang, Jen-Yu
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Tien, Chung-Hao
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Shieh, Han-Ping D.
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光電工程學系
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Department of Photonics
We present a novel fiber-based near-field optical head consisting of a straw-shaped writing probe and a flat gap sensing probe. The straw-shaped probe with a C-aperture on the end face exhibits enhanced transmission by a factor of 3 orders of magnitude over a conventional fiber probe due to a hybrid effect that excites both propagation modes and surface plasmon waves. In the gap sensing probe, the spacing between the probe and the disk surface functions as an external cavity. The high sensitivity of the output power to the change in the gap width is used as a feedback control signal. We characterize and design the straw-shaped writing probe and the flat gap sensing probe. The dual-probe system is installed on a conventional biaxial actuator to demonstrate the capability of flying over a disk surface with nanometer position precision. (C) 2007 Optical Society of America.
Reducing exciton-longitudinal-optical phonon interaction with shrinking ZnO quantum dots
(2007-10-29)
Hsu, Wei-Tse
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Lin, Kuo-Feng
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Hsieh, Wen-Feng
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光電工程學系
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Department of Photonics
The exciton-longitudinal-optical-phonon (LO-phonon) interaction was observed to decrease with reducing ZnO particle size to its exciton Bohr radius (a(B)). The unapparent LO-phonon replicas of free exciton (FX) emission and the smaller FX energy difference between 13 and 300 K reveal decreasing weighting of exciton-LO phonon coupling strength. The diminished Frohlich interaction mainly results from the reducing a(B) with size due to the quantum confinement effect that makes the exciton less polar. (C) 2007 American Institute of Physics.
Method for eliminating crosstalk in a metal programmable read only memory
(2007-10-30)
Chang
;
Meng-Fan
;
Wen
;
Kuei-Ann
The present invention provides a method for eliminating crosstalk (coupling noise) in a metal programmable read only memory. The metal programmable read only memory comprises a plurality of bit lines, a plurality of word lines, a plurality of precharge transistors, and a plurality of clamp transistors. When one of the bit lines is selected, bit lines adjacent to the selected bit line are fixed to a voltage value (VDD, GND or other voltages) by the clamp transistors. The clamping method can not cause voltage drops to the adjacent bit lines, and the crosstalk on the selected bit line can be eliminated simultaneously, so that the problem of read failures caused by the crosstalk in the high-speed metal programmable read only memory can be solved, and a higher speed can be reached.
Deposition of mesoporous silicon carbide thin films from (Me3Si)(4)Sn: Tin nanoparticles as in situ generated templates
(2007-10-30)
Wang, Chia-Hsin
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Shen, Wen-Yih
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Sheng, Pei-Sun
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Lee, Chi-Young
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Chiu, Hsin-Tien
With use of Sn(SiMe3)(4) as the precursor, amorphous SiC1+x thin films with Sri nanoparticles embedded were grown on Si substrates at 923 K by low-pressure chemical vapor deposition. After treatment under hydrogen plasma at 923 K, the Sri nanoparticles in the films were removed by an HF solution and by evaporation at 1423 K. Following the removal of Sri, high-temperature treatments at 1273-1423 K converted the amorphous thin films into mesoporous semiconducting beta-SiC thin films with pore sizes 10-100 nm.
Picogram detection of metal ions by melanin-sensitized piezoelectric sensor
(2007-10-31)
Huang, G. Steven
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Wang, Meng-Te
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Su, Chia-Wei
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Chen, Yu-Shiun
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Hong, Meng-Yen
A heavy metal ion sensor was constructed by cross-linking melanin onto the gold electrode of quartz crystal microbalance (QCM). A mercury ion sensitivity of 518 +/- 37 Hz/ppm was observed, a substantial increase in sensitivity compared to previous reports of 10-50 Hz/ppm with the limit of detection at 5 ppb. Detection of other metal ions including Sn2+, Ge4+, Li+, Zn2+, Cu2+, Bi3+, Co2+, Al3+, Ni2+, Ag+, and Fe3+ were also performed. Unexpectedly, binding of Mn7+, Ph2+, Cd2+, and Cr3+ increased resonant frequencies. The surface profile of melanin thin film upon binding to metal ions was investigated by atomic force microscopy (AFM). Structural change of melanin upon binding to metal ions was characterized by circular dichroism and by infrared spectroscopy. The current study provides the first example of melanin-coated piezoelectric sensor showing high sensitivity and selectivity to metal ions. (c) 2007 Elsevier B.V. All rights reserved.
Fabrication of an ultra-nanocrystalline diamond-coated silicon wire array with enhanced field-emission performance
(2007-10-31)
Tzeng, Yu-Fen
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Liu, Kao-Hsiang
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Lee, Yen-Chih
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Lin, Sue-Jian
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Lin, I-Nan
Large- area ultra- nanocrystalline diamond- coated silicon nanowire ( UNCD/ SiNW) field- emitter arrays were prepared by the deposition of ultra- nanocrystalline diamond ( UNCD) on the tips of arrays of silicon nanowires ( SiNWs) with uniform diameters. The electron field- emission ( EFE) behavior of UNCD/ SiNW arrays as well as that of the SiNW arrays has been observed. The SiNWs exhibit good electron field- emission properties with turn- on fields ( E0) of about 7.6 V mu m- 1, which is superior to the EFE properties of planar- silicon materials. The turn- on fields are related to the diameter of the SiNWs. Coating the SiNWs with a UNCD film further improves their EFE properties. The threshold field for attaining J(e) = 0.1 mAcm(-2) EFE current density is 16.0 V mu m(-1) for bare SiNWs and 10.2 V mu m(-1) for UNCD/ SiNWs. The improvement in EFE properties due to the UNCD coating is presumably due to the lower work function of field emission of the UNCD materials, compared to that of the silicon materials.
Advance in next Century nanoCMOSFET research
(2007-10-31)
Hwang, Huey-Liang
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Chiou, Yan-Kai
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Chang, Che-Hao
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Wang, Chen-Chan
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Lee, Kun-Yu
It is well known that Taiwan's IC industry is in the very leading front of the world, and production of 65 nm devices was launched in 2006. Within a few years, the need of high-k dielectrics and metal gates is eminent and truly indispensable. Professor H.L. Hwang (the author) organized 12 professors and 50 graduate students of National Tsing Hua University and Chiao Tung University, and executed this particular project, which is sponsored by the Ministry of Economic Affairs of Republic of China, and is aimed at treating efficiently this problem and transferred the critical technologies to industry in a time frame of 3 years. (C) 2007 Elsevier B.V. All rights reserved.
Improved stress reliability of analog TiHfO metal-insulator-metal capacitors using high-work-function electrode
(2007-11-01)
Cheng, Chun-Hu
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Chiang, Kuo-Cheng
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Pan, Han-Chang
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Hsiao, Chien-Nan
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Chou, Chang-Pin
We have studied the reliability of high-K (K similar to 49) TixHf1-xO (x similar to 0.67) metal-insulator-metal (MIM) capacitors after constant voltage stress induction. The use of a high-work-function Ni top electrode improves not only the leakage current, and temperature- and voltage-coefficients of capacitance, but also the long-term capacitance variation after stress induction.
A coupled-simulation-and-optimization approach to nanodevice fabrication with minimization of electrical characteristics fluctuation
(2007-11-01)
Li, Yiming
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Yu, Shao-Ming
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資訊工程學系
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電信工程研究所
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Department of Computer Science
In this paper, a simulation-based optimization methodology for nanoscale complementary metal-oxide-semiconductor (CMOS) device fabrication is advanced. Fluctuation of electrical characteristics is simultaneously considered and minimized in the optimization procedure. Integration of device and process simulation is implemented to evaluate device performances, where the hybrid intelligent approach enables us to extract optimal recipes which are subject to targeted device specification. Production of CMOS devices now enters the technology node of 65 nm; therefore, random-dopant-induced characteristic fluctuation should be minimized when a set of fabrication parameters is suggested. Verification of the optimization methodology is tested and performed for the 65-nm CMOS device. Compared with realistic fabricated and measured data, this approach can achieve the device characteristics; e.g., for the explored 65-nm n-type MOS field effect transistor, the on-state current > 0.35 mA/mu m, the off-state current < 1.5e - 11 A/mu m, and the threshold voltage = 0.43 V. Meanwhile, it reduces the threshold voltage fluctuation (sigma(vth) similar to 0.017 V). This approach provides an alternative to accelerate the tuning of process parameters and benefits manufacturing of nanoscale CMOS devices.
Method for virtual bass synthesis
(2007-11-01)
Bai, Mingsian R.
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Tseng, Wen-Liang
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Lin, Wan-Chi
This invention relates to a method for virtual bass synthesis. The low frequency signal is attained by applying a low pass filter to the original. In order to reduce the operations, process of down sampling the low frequency signal, moving the low frequency signal to a series of harmonics whose frequencies are integral times as large as the frequency of low frequency signals, and then up sampling them are provided. By means of psycho-acoustic theory, the weights of harmonics are attained and applied to the harmonics. Finally the weighted harmonics are combined to produce the bass signal. As the result, the virtual bass effect which is almost the same as the low frequency of the original audio signal can be accomplished. Because the harmonic signals are high frequency ones, the virtual effect can be made in the panel speakers or ordinary low-end speakers.
A multi-criterion interaction-oriented model with proportional rule for designing supply chain networks
(2007-11-01)
Che, Z. H.
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Wang, H. S.
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Sha, D. Y.
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工業工程與管理學系
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Department of Industrial Engineering and Management
Supply chain management has offered a way to improve the industrial environment becomes more competitive. While, the commonly seen methodologies may be effective in solving the production-distribution problem only from supplier- or customer-oriented consideration, those cannot present the interactive relationship between upstream and downstream enterprises. In the competitive semiconductor industry environment, considering the viewpoints of the supplier and consumer simultaneously is particularly required, because multiple manufacturing and demanding steps are performed at separate situations, concurrently. In this paper, we propose an interaction-oriented approach, which bases on the analytic hierarchy process (AHP) methodology and proportional rule, to solve the semiconductor distribution problem with multiple quantitative and qualitative criteria. The developed approach gives an expected satisfaction for the all participators of the whole chain while the cooperative information is shared perfectly and effectively. Analysis results demonstrate the proposed methodology is efficient and effective through a real world case study. (c) 2006 Elsevier Ltd. All rights reserved.
The identification of positive clones in a general inhibitor model
(2007-11-01)
Hwang, F. K.
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Chang, F. H.
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應用數學系
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Department of Applied Mathematics
In using pooling designs to identify clones containing a specific subsequence called positive clones, sometimes there exist nonpositive clones which can cancel the effect of positive clones. Various models have been studied which differ in the power of cancellation. Although the various models pose interesting mathematical problems, and ingenious constructions of pooling designs have been proposed, in practice we rarely are sure about the true model and thus about which pooling design to use. In this paper we give a pooling design which fits all inhibitor models, and does not use more tests than in the more specific models. In particular, we obtain a I-round pooling design for the k-inhibitor model for which only sequential designs are currently known. (c) 2007 Elsevier Inc. All rights reserved.
手指指向偵測系統及方法
(2007-11-01)
黃仲陵
;
傅智銘
;
簡敬宇
本發明係提供一種手指指向偵測系統及方法，其係以數台影像擷取裝置擷取使用者之數張手部影像，並以一處理器對擷取之數張手部影像進行影像處理求出數條手指指向線，利用座標轉換程式轉換出手指指向線於指向平面上的投影線，最後計算數條投影線之交點，即為使用者手指指向之目標點。本發明不需使用任何定位手套或標記手套即可偵測出使用者指向一平面上之任意目標點，具有高辨析度及高準確率，且可應用於簡報系統，作為取代雷射筆或滑鼠之人機介面。
Multiobjective planning of surface water resources by multiobjective genetic algorithm with constrained differential dynamic programming
(2007-11-01)
Yang, Chao-Chung
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Chang, Liang-Cheng
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Yeh, Chao-Hsien
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Chen, Chang-Shian
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土木工程學系
Owing to the conflict encountered between the two objectives of fixed cost in reservoir installation and operating cost in time-varying water deficit, multiobjective planning of surface water resources is a difficult job. Instead of combining these two objectives into just one objective using the weighting factor approach, this investigation proposes a novel method by integrating a multiobjective genetic algorithm (MOGA) with constrained differential dynamic programming (CDDP). A MOGA is employed to generate the various combinations of reservoir capacity and estimate the noninferior solution set. However, applying this algorithm to solve the dynamics of the operating cost, the number of variables increasing with time will dramatically increase the use of computational resources. Consequently, the CDDP is herein adopted to distribute optimal releases among reservoirs to satisfy water demand as much as possible. Next, the effectiveness of the proposed methodology is verified by solving a multiobjective planning problem of surface water in southern Taiwan. This real application demonstrates that MOGA can be linked with CDDP to resolve a complex water resources problem. Additionally, the ability of MOGA on addressing multiple objectives simultaneously without converting to a weighted objective function provides the opportunity for significant advancement in multiobjective optimization. Finally, this investigation also proposes three suitable strategies of reservoir construction to decision makers With budget concerns through the analysis of all noninferior solutions.
Distributed clustering algorithms for data-gathering in wireless mobile sensor networks
(2007-11-01)
Liu, Chuan-Ming
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Lee, Chuan-Hsiu
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Wang, Li-Chun
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交大名義發表
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National Chiao Tung University
One critical issue in wireless sensor networks is how to gather sensed information in an energy-efficient way since the energy is a scarce resource in a sensor node. Cluster-based architecture is an effective architecture for data-gathering in wireless sensor networks. However, in a mobile environment, the dynamic topology poses the challenge to design an energy-efficient data-gathering protocol. In this paper, we consider the cluster-based architecture and provide distributed clustering algorithms for mobile sensor nodes which minimize the energy dissipation for data-gathering in a wireless mobile sensor network. There are two steps in the clustering algorithm: cluster-head election step and cluster formation step. We first propose two distributed algorithms for cluster-head election. Then, by considering the impact of node mobility, we provide a mechanism to have a sensor node select a proper cluster-head to join for cluster formation. Our clustering algorithms will achieve the following three objectives: (1) there is at least one cluster-head elected, (2) the number of cluster-heads generated is uniform, and (3) all the generated clusters have the same cluster size. Last, we validate our algorithms through an extensive experimental analysis with Random Walk Mobility (RWM) model, Random Direction Mobility (RDM) model, and a Simple Mobility (SM) model as well as present our findings. (C) 2007 Elsevier Inc. All rights reserved.
Glass transition temperatures of epoxy modified with pendent nano-organic rigid-rod compounds
(2007-11-01)
Lin, S. P.
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Han, J. L.
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Chen, R. Z.
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Yeh, J. T.
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Chang, F. C.
Pendent nanoscale organic rigid-rod compounds are molecular fiber-like materials that can be used to reinforce the polymer matrix. In this study, 4,4'-diphenylmethane diisocyanate (MDI) was used to covalently connect a number of organic rigid-rod compounds [4'-hydroxyphenyl-4-hydroxy-benzoate (HPHB), phenyl 4-hydroxybenzoate (HPB), 4,4'-isopropylidenediphenol (BSPA), and 2-naphthol (NPT)] to the secondary hydroxyl groups of the epoxy resin. These reactions were monitored using Fourier transform infrared (FTIR) spectroscopy; the products were characterized using nuclear magnetic resonance (NMR) spectroscopy. The glass transition temperatures of the organic rigid-rod compounds modified epoxy resins were investigated through differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). Thermogravimetric analysis (TGA) was used to detect the values of Td and the thermal stabilities of the polymers.
The impact of fabrication errors on a flat-top grating-based planar waveguide demultiplexer
(2007-11-01)
Lin, Chun-Ting
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Huang, Yang-Tung
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Huang, Jung-Yaw
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電子工程學系及電子研究所
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光電工程學系
The spectral performance of a demultiplexer is significantly affected by the phase and amplitude errors due to fabrication errors. We estimate the impact of fabrication errors on a flat-top grating-based planar waveguide demultiplexer using a design example. Simulation results show that the photomask resolution resulting in a phase error should be lower than 40 nm when a crosstalk criterion of -30 dB is given. The impact of amplitude errors is not distinct until the reduced amount of the facet width is greater than 0.5 mu m and the grating side-wall angle offset from the vertical is larger than 1 degrees.
Local structure formation in alkyl-imidazolium-based ionic liquids as revealed by linear and nonlinear Raman spectroscopy
(2007-11-01)
Iwata, Koichi
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Okajima, Hajime
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Saha, Satyen
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Hamaguchi, Hiro-O
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應用化學系
We show several pieces of Raman spectroscopic evidence that are indicative of local structure formation in imidazolium-based ionic liquids. Low-frequency Raman spectra of C(n)mimX, where C(n)mim stands for 1-alkyl(CnH2n+1)-3-methylimidazolium cation and X represents the anion, exhibit broad bands assignable to collective modes of local structures. Spatial distributions of coherent anti-Stokes Raman scattering (CARS) signals from C(n)mim[PF(6)l are consistent with local structures whose size increases with increasing n. Picosecond Raman spectra of S, trans-stilbene as a "picosecond Raman thermometer" show microscopic thermal inhomogeneity ascribable to local structure formation in C(2)mimTf(2)N and C(4)mimTf(2)N. We also describe two novel phenomena that we believe are relevant to extraordinary nanoenvironments generated by local structures in a magnetic ionic liquid C(4)mim[FeCl4].