Browsing by Issue Date, starting with "2013-11-04"

Now showing 1 - 20 of 30178

The versatile designs and optimizations for cylindrical TiO2-based scatterers for solar cell anti-reflection coatings
(2013-11-04)
Lin, Albert
;
Zhong, Yan-Kai
;
Fu, Sze-Ming
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電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
The anti-reflection coating(ARC) based on dielectric nanoparticles has been recently proposed as a new way to achieve the low reflectance required for solar cell front surfaces. In this scenario, the Mie modes associated with the dielectric nano-particles are utilized to facilitate photon forward scattering. In this work, versatile designs together with systematically optimized geometry are examined, for the ARCs based on dielectric scatterers. It is found that the Si3N4-TiO2 or SiO2-TiO2 stack is capable of providing low reflectance while maintaining a flat and passivated ARC-semiconductor interface which can be beneficial for reduced interface recombination and prevent V-OC degradation associated with topography on the active materials. It is also confirmed that the plasmonic nano-particles placed at the front side of solar cells is not a preferred scheme, even with thorough geometrical optimization. At the ultimate design based on mixed graded index(GI) Mie-scattering, the averaged reflectance can be as low as 0.25%. Such a low reflectance is currently only achievable by ultra-long silicon nano-tips, but silicon nanotips introduce severe surface recombination. On the other hand, the mixed GI Mie design preserves a flat and passivated ARC-silicon interface, with total thickness reduced to 279.8nm, much thinner than 1.6 mu m for silicon nanotips. In addition, the light trapping capability of mixed GI Mie design is much better than silicon nanotips. In fact, when compared to the state-of-art TiO2 light trapping anti-reflection coating, the mixed GI Mie design provides same light trapping capability while providing much lower reflectance. (C) 2013 Optical Society of America
Real-time white-light phosphor-LED visible light communication (VLC) with compact size
(2013-11-04)
Yeh, Chien-Hung
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Liu, Yen-Liang
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Chow, Chi-Wai
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光電工程學系
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Department of Photonics
In this demonstration, we first demonstrate a real-time phosphor-LED visible light communication (VLC) system with 37 Mbit/s total throughput under a 1.5 m free space transmission length. The transmitter and receiver modules are compact size. Utilizing our proposed pre-equalization technology, the similar to 1 MHz bandwidth of phosphor LED could be extended to similar to 12 MHz without using blue filter. Thus, the increase in bandwidth would enhance the traffic data rate for VLC transmission. The maximum bit-rate achieved by the VLC system is 37 Mbit/s, and a video transmission at 28.419 Mbit/s is demonstrated using the proposed VLC system. In addition, the relationships of received power and signal performance are discussed and analyzed. (C) 2013 Optical Society of America
Roton instabilities and correlated Wigner crystals of rotating dipolar fermions in the fractional quantum Hall regime
(2013-11-04)
Jheng, Shih-Da
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Jiang, T. F.
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Cheng, Szu-Cheng
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物理研究所
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Institute of Physics
We point out that the Wigner crystal (WC) state of rotating dipolar fermions in the lowest Landau level is strongly correlated. From intra-Landau-level excitations of the fractional quantum Hall effect (FQHE) liquid, we find that the roton minimum of the excitation spectrum at. nu = 1/7 becomes negative, indicating an absence of the FQHE state, which is supposed to be the ground state of the system. Therefore, we show that the Hartree-Fock theory of the WC does not predict the correct ground-state energy in the lowest Landau level. There exists a strong correlation effect on the Wigner crystallization of rotating dipolar gases.
Room temperature ultraviolet GaN metal-coated nanorod laser
(2013-11-04)
Hsu, Yu-Cheng
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Sou, Kuok-Pan
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Chang, Shih-Pang
;
Hsu, Kung-Shu
;
Shih, M. H.
This study demonstrates a room-temperature ultraviolet GaN/Al nanorod (NR) metal laser with an optimized sidewall. A wet-chemical etching process with potassium hydroxide was used to control the GaN NR sidewall angle and polish the NR surface. The lasing action was observed near a wavelength of 365 nm with a low threshold power density of 5.2 mJ/cm(2). The high-quality factor (Q) surface plasmon lasing modes were characterized with experiments and three-dimensional finite-element method simulations. We also studied the optical modes in GaN metal-coated NR with and without an Al layer and verified the metal layer is necessary for high-Q resonant modes. (c) 2013 AIP Publishing LLC.
High-power tunable single- and multi wavelength diode-pumped Nd:YAP laser in the F-4(3/2) -> I-4(11/2) transition
(2013-11-04)
Tzeng, Y. S.
;
Huang, Y. J.
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Tang, C. Y.
;
Su, K. W.
;
Chen, W. D.
We experimentally explore the fluorescent spectrum of the Nd:YAP crystal to manifest the feasibility of tunable single-and multi-wavelength operations in the F-4(3/2) -> I-4(11/2) transition. An intracavity etalon is subsequently exploited to effectively select spectral lines at 1073, 1080, and 1084 nm with the tunabilities of 0.56, 1.13, and 0.1 nm, respectively. We also experimentally obtain multi-wavelength oscillations among various intermanifold lines in the Nd:YAP crystal with the output powers on the order of several watts for each group. Employing the Cr4+:YAG crystal to realize the passively Q-switched operation, the maximum average output powers as high as 2.3 and 3.5 W for 1073 and 1080 nm are obtained. The corresponding pulse energies at 1073 and 1080 nm are up to 177 and 159 mu J, respectively. (C) 2013 Optical Society of America
Investigation of quantum dot passively mode-locked lasers with excited-state transition
(2013-11-04)
Cheng, Hsu-Chieh
;
Lee, Chien-Ping
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Monolithic passively mode-locked quantum dot lasers with excited-state transition were investigated in a broad operating range without ground-state lasing. Optical and electrical characteristics of these mode locked lasers were studied in detail at different levels of injection current and absorber bias. Very different behaviors in the evolution of the hysteresis, the optical spectra and the evolution of repetition frequency were observed between our lasers and conventional quantum dot lasers with ground-state transition. Possible mechanisms behind these observed phenomena were proposed and discussed. A minimum pulse width of 3.3 ps and an externally compressed pulse width of 0.78 ps were obtained. (C) 2013 Optical Society of America
Method of forming single-layer photonic crystal structure
(2013-11-05)
Wu Pu-Wei
;
Huang Yi-Jui
A method of forming a single-layer photonic crystal structure. The method includes depositing electrophoretic suspension, working electrode and lower electrode in a container, wherein the working electrode and the lower electrode are formed at upper and lower parts of the container, respectively, and spaced apart at an distance; and applying an electric voltage to the working electrode and the lower electrode to form an electric field, such that particles in the electrophoretic suspension form a single-layer photonic crystal structure on the working electrode under interactive actions of the electric field and a gravity field by an electrophoresis self-assembly technique. Therefore, the single-layer photonic crystal structure has a low cost, and good quality and recurring property.
The direction decoupled Quiet Direct Simulation method for rapid simulation of axisymmetric inviscid unsteady flow in pulsed pressure chemical vapour deposition
(2013-11-05)
Lim, C. W.
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Smith, M. R.
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Cave, H. M.
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Jermy, M. C.
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Wu, J. -S.
Pulsed Pressure-Chemical Vapour Deposition (PP-CVD) is a thin film deposition process which employs a highly unsteady flow with wide dynamic range of pressure. The large, time-varying density gradient during a PP-CVD process cycle produces a flow field in which the Knudsen number varies from the near-continuum to the rarefied regimes, making Direct Simulation Monte Carlo (DSMC) prohibitively expensive. The present directional decoupled Quiet Direct Simulation (DD-QDS) method is a novel kinetic-based flux scheme that computes fluxes of mass, momentum and energy at the interface of computational cells in a highly computationally efficient manner. The Maxwell-Boltzmann equilibrium distribution is enforced locally at each computational cell at each time step. In this paper, an axisymmetric second order directional decoupled QDS scheme is used to simulate highly unsteady flows encountered in PP-CVD reactor. Two simulations were conducted to investigate the PP-CVD reactor flow field at 1 Pa and 1 kPa reactor base pressures. The assumption of the local Maxwell-Boltzmann equilibrium distribution used in the QDS scheme is verified by examining the gradient length local Knudsen number based on the density, and by estimating the average number of molecular collisions within each computational cell in one computational time step. The validity of the local equilibrium assumption is found satisfactory at 1 kPa reactor based pressure but not at 1 Pa. The limitation of the QDS scheme in modelling PP-CVD flow was also investigated. The time required to establish the quasi-steady under-expanded jet is found to be similar to 4 ms, and the jet dissipates within 0.5 ms of the end of injection. This important information is required to set up PP-CVD operating conditions which give uniform film deposition. (C) 2013 Elsevier Ltd. All rights reserved.
交大e-News第151期
(2013-11-05)
Secretariat
;
國立交通大學秘書室
Frame prediction system and prediction method thereof
(2013-11-05)
Peng Wen-Hsiao
;
Chen Yi-Wen
A frame prediction system and a prediction method thereof. An initializing module initializes a first image block having a plurality of pixels. A providing module provides a first centroid and a first motion vector of a second image block. The location lookup module finds a location according to the first centroid, and generates a first weight and a second weight respectively according to a relationship between each of the pixels, the first centroid and the location. A vector lookup module finds a second motion vector, which gives a minimum pixel intensity error for the plurality of pixels in the first image block according to the first centroid, the first motion vector, the location, the first weight and the second weight. A processing module sequentially calculates a plurality of predictive intensity values according to the motion vectors and the weights.
Specimen box for electron microscope
(2013-11-05)
Chen Chih
;
Tu King-Ning
The present invention relates to a specimen box for an electron microscope, which comprises a first substrate, a second substrate, and a metal adhesion layer. The first substrate has a first surface, a second surface, a first concave, and one or more first through holes, wherein the first through hole penetrates through the first substrate. The second substrate has a third surface, a forth surface, and a second concave. Besides, the metal adhesion layer is disposed between the first substrate and the second substrate to form a space for a specimen placed therein. In addition, the specimen box of the present invention further comprises one or more plugs. When the plug is assembled into the first through hole to seal the specimen box, the in-situ observation can be accomplished by using an electron microscope.
Modeling complex responses of FM-sensitive cells in the auditory midbrain using a committee machine
(2013-11-06)
Chang, T. R.
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Chiu, T. W.
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Sun, X.
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Poon, Paul W. F.
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生物科技學系
Frequency modulation (FM) is an important building block of complex sounds that include speech signals. Exploring the neural mechanisms of FM coding with computer modeling could help understand how speech sounds are processed in the brain. Here, we modeled the single unit responses of auditory neurons recorded from the midbrain of anesthetized rats. These neurons displayed spectral temporal receptive fields (STRFs) that had multiple-trigger features, and were more complex than those with single-trigger features. Their responses have not been modeled satisfactorily with simple artificial neural networks, unlike neurons with simple-trigger features. To improve model performance, here we tested an approach with the committee machine. For a given neuron, the pen-stimulus time histogram (PSTH) was first generated in response to a repeated random FM tone, and peaks in the PSTH were segregated into groups based on the similarity of their pre-spike FM trigger features. Each group was then modeled using an artificial neural network with simple architecture, and, when necessary, by increasing the number of neurons in the hidden layer. After initial training, the artificial neural networks with their optimized weighting coefficients were pooled into a committee machine for training. Finally, the model performance was tested by prediction of the response of the same cell to a novel FM tone. The results showed improvement over simple artificial neural networks, supporting that trigger-feature-based modeling can be extended to cells with complex responses. (C) 2013 Elsevier B.V. All rights reserved.
High-k shallow traps observed by charge pumping with varying discharging times
(2013-11-07)
Ho, Szu-Han
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Chang, Ting-Chang
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Lu, Ying-Hsin
;
Wang, Bin-Wei
;
Lo, Wen-Hung
In this paper, we investigate the influence of falling time and base level time on high-k bulk shallow traps measured by charge pumping technique in n-channel metal-oxide-semiconductor field-effect transistors with HfO2/metal gate stacks. N-T-V-high level characteristic curves with different duty ratios indicate that the electron detrapping time dominates the value of N-T for extra contribution of I-cp traps. N-T is the number of traps, and I-cp is charge pumping current. By fitting discharge formula at different temperatures, the results show that extra contribution of I-cp traps at high voltage are in fact high-k bulk shallow traps. This is also verified through a comparison of different interlayer thicknesses and different TixN1-x metal gate concentrations. Next, N-T-V-high level characteristic curves with different falling times (t(falling time)) and base level times (t(base level)) show that extra contribution of I-cp traps decrease with an increase in t(falling time). By fitting discharge formula for different t(falling time), the results show that electrons trapped in high-k bulk shallow traps first discharge to the channel and then to source and drain during t(falling time). This current cannot be measured by the charge pumping technique. Subsequent measurements of N-T by charge pumping technique at t(base level) reveal a remainder of electrons trapped in high-k bulk shallow traps. (c) 2013 AIP Publishing LLC.
OPTICAL FILM AND BACKLIGHT MODULE USING THE SAME
(2013-11-07)
HU Ya-Wen
;
PAN Jui-Wen
An optical film applied in a backlight module is provided. The optical film includes a basic layer, a plurality of periodically arranged reflective convex-parts and a plurality of periodically arranged collimating parts. The reflective convex-parts are disposed on the first surface of the basic layer. The reflective convex-part includes at least one reflective side surface and an incident bottom surface contacting a light guide plate. The collimating parts are disposed on the second surface of the basic layer. The reflective convex-parts are respectively corresponded to the collimating parts. In each corresponding pair of the reflective convex-part and the collimating part, a central axis of the reflective convex-part is substantially coincided with a central axis of the collimating part. In addition, a backlight module using the optical film is also provided.
MINIATURE MICROSCOPE AND MANUFACTURING METHOD OF OPTICAL ELEMENT THEREOF
(2013-11-07)
SUN Ching-Cherng
;
YU Yeh-Wei
;
CHENG Chih-Yuan
A manufacturing method of an optical element applied to a miniature microscope comprises the steps of: emitting a signal light and a reference light to an optical material; and forming a plurality of gratings on the optical material by interfering the signal light and the reference light. A miniature microscope is also disclosed.
METHOD OF IMPLEMENTING TIMING ENGINEERING CHANGE ORDER
(2013-11-07)
Chang Hua-Yu
;
Jiang Hui-Ru
;
Chang Yao-Wen
A method of implementing timing ECO in a circuit includes the steps of performing a static timing analysis on the circuit so as to determine at least one timing violating path of the circuit, decomposing the timing violating path into at least one violating path segment, determining a smooth curve from each timing violating path and determining a plurality of reference points along the smooth curve, computing a fixability parameter of each gate on the violating path segment, extracting at least one gate according to the fixability parameters, and selecting one spare cell and disposing the selected spare cell on the violating path segment.
Collective excitations, Nambu-Goldstone modes, and instability of inhomogeneous polariton condensates
(2013-11-08)
Chen, Ting-Wei
;
Cheng, Szu-Cheng
;
Hsieh, Wen-Feng
;
光電工程學系
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Department of Photonics
We study nonequilibrium polariton condensates in a harmonic potential trap. After finding the steady-state density and supercurrent distributions of nonequilibrium condensates, we calculate the collective excitations of the system. From collective excitation spectra, we can identify the bifurcation of the stable and unstable modes in terms of the pumping spot size and power. There exist Nambu-Goldstone modes that reveal the pattern of the spontaneous symmetry breaking of the system. Moreover, the unstable mechanism associated with the inward supercurrent flow is characterized by the existence of a supersonic region within the condensate.
《笑傲江湖》與我經歷的轉變
(2013-11-10)
林妍君
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Department of Communication and Technology
;
傳播與科技學系
從小就嚮往這樣的人格特質，可以對惡勢力無所畏懼、待人接物至誠至性、對所謂的傳統禮教框架不屑一顧，能夠極其自然地詮釋「瀟灑」二字。令狐沖最令人激賞的地方，在於他能不畏強權，敢於維護自己堅守的俠義心腸，尤其是幾次面臨危難時，他都可以為了正義而置生死于度外。
難以忘懷的住校點滴
(2013-11-10)
林庭宇
;
Department of Communication and Technology
;
傳播與科技學系
記憶中，多少次認為以前的事情會深深地影響現在，不管是多麼雞毛蒜皮的事情，任何事情都有它的因果，人的個性格亦是如此。
歡慶萬聖節　不給糖就搗蛋
(2013-11-10)
許仲廷
;
林婉婷
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Department of Communication and Technology
;
傳播與科技學系
西門萬聖節慶祝活動於十月二十六日下午正式展開，吸引了大批人潮前來參加。除了各式各樣的活動可以讓民眾一同參與，更有專業的DJ以及舞蹈團體帶來精彩的表演，讓整個西門町充滿了歡樂的節慶氣氛，也帶來許多商機。