Browsing by Issue Date, starting with "2006-12-04"

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詩與歌的宴饗
(2006-12-04)
本報訊
Investigation of whispering gallery mode dependence on cavity geometry of quasiperiodic photonic crystal microcavity lasers
(2006-12-04)
Lee, Po-Tsung
;
Lu, Tsan-Wen
;
Tsai, Feng-Mao
;
Lu, Tien-Chang
;
光電工程學系
Dodecagonal (12-fold) quasiperiodic photonic crystal (DQPC) microcavity lasers sustaining whispering gallery mode (WGM) are fabricated. Lasing characteristics of DQPC D2 microcavity lasers are obtained and compared with triangular lattice D2 photonic crystal (PC) lasers, and ultralow threshold is obtained. The strong WGM mode dependence on 12 nearest airholes of DQPC D2 microcavity and its fabrication tolerance is investigated and discussed by randomly varying the lattice of two separate regions. This mode dependence also indicates that one can enhance a WGM in different PC microcavities by modifying the cavity boundary to be circular. (c) 2006 American Institute of Physics.
Charge pump circuit suitable for low-voltage process
(2006-12-05)
Ker
;
Ming-Dou
;
Tsai
;
Chia-Sheng
The present invention discloses a charge pump circuit suitable for a low-voltage process. The charge pump circuit is composed of stages of the voltage amplifying circuits connected each other, and the operation of two adjacent stages of voltage amplifying circuit is controlled by two opposite set of the timing signals. Each stage of the voltage amplifying circuit has a coupled pair of a first complementary MOS (CMOS) transistor and a second CMOS transistor switching in accordance with a timing signal and an inverse timing signal inputted into the first and second capacitors. Then, two diode devices guide charges to next stage, and a voltage higher than the integrated circuit voltage source is outputted. The present invention has advantage of high pumping gain, and the reliability issue of the gate oxide layer in the low-voltage process can be also solved.
Dissociation dynamics of positive-ion and negative-ion fragments of gaseous and condensed Si(CH3)(2)Cl-2 via Si 2p, Cl 2p, and Cl 1s core-level excitations
(2006-12-07)
Chen, J. M.
;
Lu, K. T.
;
Lee, J. M.
;
Chen, C. K.
;
Haw, S. C.
The state-selective positive-ion and negative-ion dissociation pathways of gaseous and condensed Si(CH3)(2)Cl-2 following Cl 2p, Cl 1s, and Si 2p core-level excitations have been characterized. The excitations to a specific antibonding state (15a(1)(*) state) of gaseous Si(CH3)(2)Cl-2 at the Cl 2p, Cl 1s, and Si 2p edges produce significant enhancement of fragment ions. This ion enhancement at specific core-excited states correlates closely with the ion kinetic energy distribution. The results deduced from ion kinetic energy distribution are consistent with results of quantum-chemical calculations on Si(CH3)(2)Cl-2 using the ADF package. The Cl- desorption yields for Si(CH3)(2)Cl-2/Si(100) at similar to 90 K are notably enhanced at the 15a(1)(*) resonance at both Cl 2p and Si 2p edges. The resonant enhancement of Cl- yield occurs through the formation of highly excited states of the adsorbed molecules. These results provide insight into the state-selective ionic fragmentation of molecules via core-level excitation. (c) 2006 American Institute of Physics.
Modeling carbon nanostructures with the self-consistent charge density-functional tight-binding method: Vibrational spectra and electronic structure of C-28, C-60, and C-70
(2006-12-07)
Witek, Henryk A.
;
Irle, Stephan
;
Zheng, Guishan
;
de Jong, Wibe A.
;
Morokuma, Keiji
The self-consistent charge density-functional tight-binding (SCC-DFTB) method is employed for studying various molecular properties of small fullerenes: C-28, C-60, and C-70. The computed bond distances, vibrational infrared and Raman spectra, vibrational densities of states, and electronic densities of states are compared with experiment (where available) and density-functional theory (DFT) calculations using various basis sets. The presented DFT benchmark calculations using the correlation-consistent polarized valence triple zeta basis set are at present the most extensive calculations on harmonic frequencies of these species. Possible limitations of the SCC-DFTB method for the prediction of molecular vibrational and optical properties are discussed. The presented results suggest that SCC-DFTB is a computationally feasible and reliable method for predicting vibrational and electronic properties of such carbon nanostructures comparable in accuracy with small to medium size basis set DFT calculations at the computational cost of standard semiempirical methods. (c) 2006 American Institute of Physics.
Hyperboloid structures formed by polarization singularities in coherent vector fields with longitudinal-transverse coupling
(2006-12-08)
Chen, Y. F.
;
Lu, T. H.
;
Huang, K. F.
;
電子物理學系
;
Department of Electrophysics
The propagation-dependent polarization vector fields are experimentally created from an isotropic microchip laser with a longitudinal-transverse coupling and entanglement of the polarization states. The experimental three-dimensional coherent vector fields are analytically reconstructed with a coherent superposition of orthogonal circularly polarized vortex modes. Each polarized component is found to comprise two Laguerre-Gaussian modes with different topological charges. With the analytical representation, the polarization singularities, on which the electric polarization ellipse is purely circular (C lines) or purely linear (L surfaces), are explored. The C line singularities are found to form an intriguing hyperboloidal structure.
Development and verification of a coupled DSMC-NS scheme using unstructured mesh
(2006-12-10)
Wu, J. -S.
;
Lian, Y. -Y.
;
Cheng, G.
;
Koomullil, R. P.
;
Tseng, K. -C.
An efficient and accurate parallel coupled DSMC-NS method using three-dimensional unstructured grid topology is proposed and verified for the simulation of high-speed gas flows involving continuum and rarefied regimes. A domain overlapping strategy, taking advantage of unstructured data format, with Dirichlet-Dirichlet type boundary conditions based on two breakdown parameters is used iteratively to determine the choice of solvers in the spatial domain. The selected breakdown parameters for this study include: (1) a local maximum Knudsen number defined as the ratio of the local mean free path and local characteristic length based on property gradient and (2) a thermal non-equilibrium indicator defined as the ratio of the difference between translational and rotational temperatures to the translational temperature. A supersonic flow (M-infinity = 4) over a quasi-2-D 25 degrees wedge is employed as the first step in verifying the present coupled method. The results of simulation using the coupled method are in excellent agreement with those of the pure DSMC method, which is taken as the benchmark solution. Effects of the size of overlapping regions and the choice of breakdown parameters on the convergence history are discussed. Results show that the proposed iteratively coupled method predicts the results more accurately as compared to the "one-shot" coupled method, which has been often used in practice. Further, a realistic 3-D nitrogen flow, which two near-continuum parallel orifice jets underexpand into a near-vacuum environment, is simulated using the present coupled method to demonstrate its capability. Finally, developments in extending the present method are also outlined in this paper. (c) 2006 Elsevier Inc. All rights reserved.
Reactive template assisted growth of one-dimensional nanostructures of titanium dioxide
(2006-12-10)
Chung, Yao-An
;
Lee, Chi-Young
;
Peng, Chih-Wei
;
Chiu, Hsin-Tien
;
材料科學與工程學系
TiCl4 was employed to react with the reactive template Na@AAO, Na inside the channels of anodic aluminum oxide membranes, followed by O-2 oxidation at 623 K and annealed at 723 and 873 K to form one-dimensional nanostructures of TiO2. Free standing polycrystals of anatase TiO2 (diameter = 200-400 nm, length = 60 mu m) were obtained after the template was removed. (c) 2006 Elsevier B.V. All rights reserved.
個人電腦之麥克風陣列系統
(2006-12-11)
胡竹生
;
鄭价呈
;
康創閔
;
劉維瀚
本發明係為一個人電腦之麥克風陣列系統，其利用通用串列匯流排資料擷取系統將類比聲音訊號放大並通過一帶通濾波器，最後將之轉換成數位聲音訊號，再利用語音訊號增強系統將擷取到之數位聲音訊號中聲音雜訊部分加以抑制並純化成一語音訊號，其整套系統具有低成本、便利性、擴充性及高彈性等優點，可在吵雜及回音存在的環境下消除非語音雜訊，且可根據語者方位、環境及器材的變動自行調整參數，以達到自動化高效能之語音純化效果。
Ferntosecond fluorescence dynamics of zinc biphenylporphine in nanocrystalline TiO2 films: Evidence for interfacial electron transfer through space
(2006-12-11)
Luo, Liyang
;
Chang, Chih-Wei
;
Lin, Ching-Yao
;
Diau, Eric Wei-Guang
;
應用化學系
The femtosecond fluorescence dynamics of zinc biphenylporphine (ZnBPP) were investigated in solution and in two solid-state environments - ZnBPP/glass and ZnBPP/TiO2 - with S-2 excitation (lambda(ex) = 410 nm and lambda(em) = 630 nm). Our results indicate that the transient in solution involves a persistent component that becomes completely quenched in thin-film samples; for solid films at least three decay coefficients are required to fit the transients. For ZnBPP/TiO2 films, the fluorescence was quenched significantly through J-type aggregation and interfacial electron transfer (IET) through space. Photocurrent measurements were also performed to confirm the existence of IET through space between ZnBPP molecules and TiO2 nanoparticles. (c) 2006 Elsevier B.V. All rights reserved.
Effect of gate metal on polymer transistor with glass substrate
(2006-12-11)
Meng, Hsin-Fei
;
Liu, Chien-Cheng
;
Jiang, Chin-Jung
;
Yeh, Yu-Lin
;
Horng, Sheng-Fu
Poly(3-hexylthiophene) (P3HT) field-effect transistors (FETs) are fabricated on glass substrates with SiO2 as a gate dielectric over the gate. Indium tin oxide (ITO), Al, and Cr are employed as gate metals. For spin-coated FET, the mobility increases from 10(-4)-10(-5) cm(2)/V s for ITO and Al gates to 10(-2) cm(2)/V s for Cr gate. After O-2 plasma treatment, the SiO2 roughness can be made as low as 0.7 nm. The mobility is further improved up to 0.3 cm(2)/V s by dip-coating P3HT. "Crossed rods" such as morphology can be observed in dip-coated FET with high mobility, indicating high degree of self-assembly facilitated by the flat SiO2 surface over Cr gate. (c) 2006 American Institute of Physics.
影像處理方法
(2006-12-11)
任慈澄
;
王聖智
;
謝曜任
本發明係揭露一種影像處理方法，適用於影像銳利度之調整，此方法係利用一空間遮蔽程序，針對影像中每對相鄰之像素點，利用至少包含該兩鄰近點之亮度值資訊，推算出可用於調昇或調降該對像素點亮度值之最大幅度調整值，以加強該兩鄰近點之間之影像銳利度。其中上述調整值在本發明中可定義為近似於該兩鄰近點之亮度差值之十分之一。
Novel self-assembled metallo-homopolymers and metallo-alt-copolymer containing terpyridyl zinc(II) moieties
(2006-12-12)
Chen, Yi-Yu
;
Tao, Yu-Tai
;
Lin, Hong-Cheu
;
材料科學與工程學系
;
Department of Materials Science and Engineering
A series of novel terpyridyl Zn(II)-based metallo-polymers, including metallo-homopolymers and metallo-alt-copolymer, containing carbazole pendants attached to the C-9 position of fluorene by long alkyl spacers were constructed by self-assembled reaction. The integrated ratios of H-1 NMR reveal a facile result to distinguish the differences between metallo-homopolymers and copolymers. To further investigate these polymers, UV-vis and PL spectral titration experiments were also carried out by varying the molar ratios of zinc(II) ions to monomers. The photophysical properties of these polymers exhibited blue PL emissions (around 420 nm) with quantum yields of 11-23% (in DMF) and the PL results revealed that the formation of excimers were suppressed by the incorporation of carbazole pendant groups. In addition, the EL results showed green EL emissions ( around 550 nm) with turn-on voltages of 6.0-6.5 V, maximum efficiencies of 0.85-1.1 cd A(-1) (at 100 mA cm(-2)), and maximum luminances of 1704-2819 cd/m(2) (around 15 V), correspondingly.
The photoluminescence decay time of self-assembled InAs quantum dots covered by InGaAs layers
(2006-12-14)
Shu, G. W.
;
Wang, C. K.
;
Wang, J. S.
;
Shen, J. L.
;
Hsiao, R. S.
The temperature dependence of the time-resolved photoluminescence (PL) of self-assembled InAs quantum dots (QDs) with InGaAs covering layers was investigated. The PL decay time increases with temperature from 50 to 170 K, and then decreases as the temperature increases further above 170 K. A model based on the phonon-assisted transition between the QD ground state and the continuum state is used to explain the temperature dependence of the PL decay time. This result suggests that the continuum states are important in the carrier capture in self-assembled InAs QDs.
High-throughput pipelined FFT processor
(2006-12-14)
Lee, Chen-Yi
;
Lin, Yu-Wei
The invention proposes a pipelined FFT processor for UWB system, comprising a first module for implementing radix-2 FFT algorithm; a second module is to realize radix-8 FFT algorithm; a third module is to realize radix-8 FFT algorithm; a plurality of conjugate blocks; a division block; and a plurality of multiplexers. The proposed pipelined FFT architecture called Mixed-Radix Multi-Path Delay Feedback (MRMDF) can provide higher throughput rate by using the multi-data-path scheme. The high-radix FFT algorithm is also realized in our processor to reduce the number of complex multiplications.
青檀寺那棵千年相抱銀杏　
(2006-12-15)
管管
青檀寺那棵千年相抱銀杏　
(2006-12-15)
管管
Effect of oxygen on characteristics of nickel oxide/indium tin oxide heterojunction diodes
(2006-12-15)
Chang, Hung-Lu
;
Lu, T. C.
;
Kuo, H. C.
;
Wang, S. C.
;
光電工程學系
p-nickel oxide (NiOx)/n-indium tin oxide heterostructure p-n junction diodes were fabricated on glass substrates and showed rectifying characteristics or negative differential resistance (NDR) characteristics depending on the content of oxygen in the NiOx films. After annealing the heterojunction diodes at 450 degrees C in air for about 30 min, the characteristics of NDR disappeared and transparent rectifying diodes were observed. The oxygen content could be observed by inspecting the characteristics of the NiOx films before and after annealing using x-ray photoelectron spectrum and thermogravimetric analysis as well as atomic force microscopy. The released oxygen in the NiOx films could be responsible for the disappearance of NDR characteristics and the change of the nonideal rectifying diode characteristics. (c) 2006 American Institute of Physics.
Study of leading factors in formation of surface wavy structures on a rubber material
(2006-12-15)
Shih, Teng-Kai
;
Chen, Chia-Fu
;
Ho, Jeng-Rong
;
Liu, Chueh-Yang
;
Chuang, Fang-Tzu
Wavy structures are often observed on the surface of a rubber material (polydimethylsiloxane, PDMS) covered with a thin metallic film. In this study we demonstrate that the orientation, periodicity, location of formation, and range of periodicity of the wavy structures can be regulated by three leading factors including the surface pattern, substrate hardness and the thickness of the metallic film. Results show the orientation of the wavy structures can be adjusted by the location, shape and size of the surface patterns. Enhancement of the substrate hardness can prevent forming random wavy structures. The thickness of surface metallic film significantly influenced the periodicity of the structures. Experimental results revealed an increase of the thickness of surface Au film by 50 nm, the periodicity was increased roughly by 1 mu m. A compound structure, combining longitudinally preset patterns and transversely induced wavy structures, and a parallel wavy structure fabricated, respectively, by suitable arrangement of pattern configurations and adjustment of substrate hardness were demonstrated. The relatively simple approaches proposed here show the potential application in fabrication of designated complicate structures. (c) 2006 Elsevier B.V. All rights reserved.
Green-pumped high-power optical parametric oscillator based on periodically poled MgO-doped stoichiometric LiTaO3
(2006-12-15)
Tu, Shih-Yu
;
Kung, A. H.
;
Gao, Z. D.
;
Zhu, S. N.
;
Kurimura, Sunao
A high-power 532 nm-pumped multikilohertz nanosecond optical parametric oscillator using a periodically poled 1.0 mol. % MgO-doped stoichiometric lithium tantalate crystal that could be operated from room temperature to 200 degrees C without damage is reported. A broad continuous tuning range from 855 to 1410 nM was achieved within a single domain period. Efficient operation of high peak power and watt level average power with a power conversion of 62.5% was measured. These results show that a high-resolution high average power visible tunable source can be realized. (c) 2006 Optical Society of America.