Browsing by Issue Date, starting with "2005-08-22"

Now showing 1 - 20 of 66184

Fabrication and performance of blue GaN-based vertical-cavity surface emitting laser employing AlN/GaN and Ta2O5/SiO2 distributed Bragg reflector
(2005-08-22)
Kao, CC
;
Peng, YC
;
Yao, HH
;
Tsai, JY
;
Chang, YH
GaN-based vertical-cavity surface emitting laser with 3 lambda cavity and hybrid mirrors, consisting of the 25 pairs AlN/GaN dielectric Bragg reflector and the 8 pairs Ta2O5/SiO2, was fabricated. The laser action was achieved under the optical pumping at room temperature with a threshold pumping energy density of about 53 mJ/cm(2). The laser emits 448 nm blue wavelength with a linewidth of 0.25 nm and the laser beam has a degree of polarization of about 84%. (c) 2005 American Institute of Physics.
Low threshold and high power output of a diode-pumped nonlinear mirror mode-locked Nd : GdVO4 laser
(2005-08-22)
Lin, JH
;
Yang, WH
;
Hsieh, WF
;
Lin, KH
;
光電工程學系
We demonstrated nonlinear mirror mode-locking of a diode-pumped Nd:GdVO4 laser by using a 10 mm long KTP crystal. The stable CW mode locking can be reached with the relative low threshold pump power as low as 2.3W. The highest output power of 2.65W at the 10W pump powers are generated with the 121-MHz repetition rate of pulses. It confirms the excellent laser performance of the Nd: GdVO4 for high-peak power of the pulse operation. (c) 2005 Optical Society of America.
A broadband fiber ring laser technique with stable and tunable signal-frequency operation: erratum (vol 13, pg 5240, 2005)
(2005-08-22)
Yeh, CH
;
Chi, S
;
光電工程學系
;
Department of Photonics
We present the corrected version of Fig. 4 below with the original caption. (c) 2005 Optical Society of America.
Method for lifting offGaN pseudomask epitaxy layerusing wafer bonding way
(2005-08-25)
Wu, Yew-Chung
;
Lin, Pei-Yen
;
Peng, Hsien-Chih
Present invention is a method for lifting off GaN pseudomask epitaxy layer using wafer bonding way, wherein GaN epitaxy is obtained by way of selective area growth on a seed and the growth is in a way of pseudomask growth over a substrate. Owing to the different thermal expansion coefficients of the substrate and the GaN seed, by way of annealing and wafer bonding, the GaN epitaxy layer and the epitaxy substrate can be separated, or the GaN epitaxy substrate can be transferred onto another substrate. Thereby, the epitaxy substrate separated is not spoiled during the transferring procedure and can be reused, which lowers the cost; and high-quality GaN epitaxy layer can be transferred to various kinds of substrates for various kinds of usage and for solving the problems of difficulties in the production or the utilization of the substrate (such as difficulties in the cutting, the conductivity, the heat-sinking, and so on.)
Method for lift off GaN pseudomask epitaxy layer using wafer bonding way
(2005-08-25)
Wu, Yew-Chung
;
Lin, Pei-Yen
;
Peng, Hsien-Chih
The epitaxial lateral overgrowth (ELOG) GaN obtains the dangling structure by using wet etching and the transferred substrate to separate from the GaN epitaxy layer by using stress concentration of thermal expansion coefficient of the transferred substrate. It is useful to separate of the GaN epitaxy layer and transferred substrate by using anneal of wafer bonding. The present invention is to provide high selective etching rate, no damage to epitaxial film, low cost, and feasibility for larger commercial sizes. The wet etching method can not damage the separated epitaxial substrate, thus the substrate can be reused. There are various choices of handling substrate for bonding, not limited by the epitaxial method. When the epitaxial film is applied in devices, the low defect density of the epitaxial film can enhance the lifetime and efficiency of the devices. The addition of this improved fabrication process does not require expensive equipment. Moreover, it will reduce the production cost. The epitaxy substrate is a recyclable substrate after separation of wet etching method and the transferred epitaxy layer obtain low defect density, lifetime improvement and low cost.
A novel method for net-shape forming of hypereutectic Al-Si alloys by thixocasting with powder preforms
(2005-08-25)
Chen, CM
;
Yang, CC
;
Chao, CG
;
材料科學與工程學系
;
Department of Materials Science and Engineering
This work presents a novel and feasible method for net-shape forming of hypereutectic A1-Si alloy parts. This method, briefly termed as powder thixocasting in this paper, combines the techniques of thixocasting and conventional powder metallurgy. Consolidated preforms made of gas-atomized and pre-alloyed A1-25Si-2.5Cu-1Mg-0.5Mn powder were used as the feedstock for thixocasting. The alloy powder was preheated under protection of argon atmosphere and then was compacted to form powder preforms. The powder preforms were quickly heated into semi-solid state by induction coils and were immediately thixocast using a die-casting machine. A die with a center gate, a long runner and plate-shaped cavities was designed to examine the feasibility of this process. Results demonstrated that the powder preforms exhibits very good formability by this unique process. The powder thixocast products have satisfied strength and substantial structure with uniform distribution of fine Si particles, while the processing temperature is suitably controlled. This novel process was also successfully used to fabricate compressor scrolls for demonstration. (c) 2004 Elsevier B.V. All rights reserved.
MEDITATION EEG INTERPRETATION BASED ON NOVEL FUZZY-MERGING STRATEGIES AND WAVELET FEATURES
(2005-08-25)
Chang, Kang-Ming
;
Lo, Pei-Chen
;
電控工程研究所
;
Institute of Electrical and Control Engineering
As the advantages of meditation have been outlined literally, scientific exploration of the meditation phenomena becomes significant. Meditation EEG may provide an access to the mental states beyond normal consciousness. It is the first attempt to score the meditation course by EEG. Wavelet analysis and fuzzy c-means (FCM) are applied in the automatic interpretation algorithm. However, FCM applied straightforward to quantitative feature vectors often results in an over-trifling interpretation. As a consequence, this paper presents novel cluster-managing strategies for achieving an interpretation closer to the result of naked-eye examination. The running gray-scale chart, derived by extracting, clustering, and coding the EEG features, reveals five different meditation scenarios differing from those of the controlled subjects.
Visible cascade emission and quantum efficiency in rare earth-activated fluoride phosphors
(2005-08-28)
Tung, CY
;
Chen, TM
;
Lee, TJ
;
Tzeng, HY
;
Jang, SM
Synthesis and light emitting properties of polyacetylenes having pendant fluorene groups
(2005-08-28)
Hsu, CS
;
Huang, CH
;
應用化學系
;
Department of Applied Chemistry
Native-NMOS-triggered SCR With faster turn-on speed for effective ESD protection in a 0.13-mu m CMOS process
(2005-09-01)
Ker, MD
;
Hsu, KC
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
In order to quickly discharge the electrostatic discharge (ESD) energy and to efficiently protect the ultrathin gate oxide, a novel native-negative-channel metal oxide semiconductor (NMOS)-triggered silicon-controlled rectifier (NANSCR) is proposed for on-chip ESD protection in a 0.13-mu m complementary metal oxide semiconductor (CMOS) process with a voltage supply of 1.2 V. The proposed NANSCR can be designed for the input, output, and power-rail ESD protection circuits without latchup danger. A new whole-chip ESD protection scheme realized with the proposed NANSCR devices is also demonstrated with the consideration of pin-to-pin ESD stress. From the experimental results, the trigger voltage, holding voltage, turn-on resistance, turn-on speed, and charged-device-model (CDM) ESD level of NANSCR can be greatly improved, as compared with the traditional low-voltage-triggering SCR (LVTSCR). Under transmission line pulsing (TLP) stress, the gate leakage current of the gate monitor device protected by the proposed NANSCR is monitored after each TLP pulse, whereas the gate leakage current is not obviously increased. Therefore, the ultrathin gate oxide of the input stage can be safely protected by the new proposed NANSCR against ESD stress in the nanoscale CMOS technology.
本質的策略，策略的本質與解釋的策略
(國立陽明交通大學出版社, 2005-09-01)
黃錦樹
Analysis of DC characteristics and small signal equivalent circuit parameters of GaAs metal-semiconductor field effect transistors with different gate lengths and different gate contours by two-dimensional device simulations
(2005-09-01)
Meng, CC
;
Su, JY
;
Yang, SM
;
電信工程研究所
;
Institute of Communications Engineering
The gate length and gate contour of a GaAs metal-semiconductor field effect transistor (MESFET) device play important roles in determining the small signal circuit parameters and large signal breakdown voltage behavior, GaAs MESFETs with different gate lengths and gate contours were studied by the two-dimensional (2-D) semiconductor device simulations to investigate the dependence of small signal circuit parameters and breakdown voltage on gate length and gate contour. The results show that gate length affects small-signal circuit parameter C(gs) while gate contour affects C(gd). The breakdown voltage has strong dependence on gate contour and little dependence on gage length.
A new approach for audio classification and segmentation using Gabor wavelets and Fisher Linear Discriminator
(2005-09-01)
Lin, RS
;
Chen, LH
;
資訊工程學系
;
Department of Computer Science
Rapid increase in the amount of audio data demands an efficient method to automatically segment or classify audio stream based on its content. In this paper, based on the Gabor wavelet features, an audio classification and segmentation method is proposed. This method will first divide an audio stream into clips, each of which contains one-second audio information. Then, each clip is classified as one of two classes or five classes. Two classes contain speech and music; pure speech, pure music, song, speech with music background, and speech with environmental noise background are for five classes. Finally, a merge technique is provided to do segmentation. In order to make the proposed method robust for a variety of audio sources: we use Fisher Linear Discriminator to obtain features with the highest discriminative ability Experimental results show that the proposed method can achieve over 98% accuracy rate for speech and music discrimination, and more than 95% for a five-way discrimination. By checking the class types of adjacent clips, we can also identify more than 95% audio scene breaks in audio sequence.
A background comparator calibration technique for flash analog-to-digital converters
(2005-09-01)
Huang, CC
;
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 calibration technique for trimming the input-referred offsets of the comparators in a flash analog-to-digital converter (ADC) without interrupting the ADC's normal operation. For a random-chopping comparator, the polarity of its offset is detected by observing the code density of its comparison results. Binary feedback is then used to digitally adjust the comparator's offset so that the offset is minimized. All calibration procedures are performed in the digital domain. The calibration performance is characterized by the converging speed of the feedback loop and the offset fluctuation due to the disturbance of the ADC's input. These two performance indexes of a background-calibrated comparator (BCC) are determined by three parameters: the probabilistic distribution of the ADC's input, the BCC's offset quantized step size, and the threshold of an internal bilateral peak detector. The offset fluctuation of a BCC can be drastically reduced by employing a windowing mechanism. The use of windowed BCCs in a flash ADC can introduce nonmonotonic-threshold (NMT) effects which include an increase in calibration settling time and an increase in sigma(V-OS). The use of uncorrelated random chopping for neighboring BCCs can ensure the validity of offset detection and mitigate the NMT effects.
ESD protection design for 1-to 10-GHz distributed amplifier in CMOS technology
(2005-09-01)
Ker, MD
;
Hsiao, YW
;
Kuo, BJ
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Two distributed electrostatic discharge (ESD) protection schemes are presented and applied to protect distributed amplifiers (DAs) against ESD stresses. Fabricated in a standard 0.25-mu m CMOS process, the DA with the first protection scheme of the equal-sized distributed ESD (ES-DESD) protection scheme, contributing an extra 300 fF parasitic capacitance to the circuit, can sustain the human-body model (HBM) ESD level of 5.5 kV and machine-model (MM) ESD level of 325 V and exhibits the flat-gain of 4.7 +/- l dB from 1 to 10 GHz. With the same amount of parasitic capacitance, the DA with the second protection scheme of the decreasing-sized distributed ESD (DS-DESD) protection scheme achieves better ESD robustness, where the HBM ESD level over 8 kV and MM ESD level is 575 V, and has the flat-gain of 4.9 +/- 1.1 dB over the 1 to 9.2-GHz band. With these two proposed ESD protection schemes, the broad-band RF performances and. high ESD robustness of the DA can be successfully codesigned to meet the application specifications.
Closure to "Electronic-Based procedure for managing unbalanced bids" by Wei-Chih Wang
(2005-09-01)
Wang, WC
;
土木工程學系
;
Department of Civil Engineering
Special issue on e-learning - Foreword
(2005-09-01)
Lewis, R
;
Chan, TW
;
Chou, C
;
Sun, CT
;
資訊工程學系
Analysis and design of one-bit noise-shaping quantizer using variable structure control approach
(2005-09-01)
Hu, J
;
Yu, SH
;
電控工程研究所
;
Institute of Electrical and Control Engineering
This paper offers a straightforward analysis of a one-bit noise-shaping quantizer based on variable structure control methods. The method uses the concept of equivalent control to access the bound on the state signals when the sliding condition is reached. For a stable loop filter, the global stability can be proved to exist by using the Lyanpunov stability theory. For an unstable loop filter, this paper proposes a state constraint approach to ensure that the sliding condition is achieved. Simulation examples and an experimental circuit constructed using off-the-shelf electronic components are given to demonstrate the correctness of the theoretical analysis.
The interplay between different forms of CAI and students' preferences of learning environment in the secondary science class
(2005-09-01)
Chang, CY
;
Tsai, CC
;
教育研究所
;
師資培育中心
;
Institute of Education
This evaluation study investigated the effects of a teacher-centered versus student-centered computer-assisted instruction (CAI) on 10th graders' earth science student learning outcomes. This study also explored whether the effects of different forms of computer-assisted instruction (CAI) on student learning outcomes were influenced by student preferences of learning environment (PLE). A total of 347 10th-grade senior high school students participated in this nonequivalent control group quasiexperiment. During a one-week period, one group of students (n = 216) were taught by a teacher-centered CAI (TCCAI) model whereas the other group of students (n = 131) were subject to a student-centered CAI (SCCAI) method. Results showed that (a) no statistically significant difference on students' earth science achievement was found for either group; (b) TCCAI, group had significantly better attitudes toward earth science than did the SCCAI group; furthermore (c) a significant PLE-treatment interaction was found on student attitudes toward the subject matter, where the teacher-centered instructional approach seemed to enhance more positive attitudes of less constructivist-oriented learning preferences students, whereas the student-centered method was more beneficial to more constructivist-oriented learning preferences students on their attitudes toward earth science in a computer-assisted learning environment. (c) 2005 Wiley Periodicals, Inc.
Influence of the direction of motion on the inelastic interaction between electrons and solid surfaces
(2005-09-01)
Li, YC
;
Tu, YH
;
Kwei, CM
;
Tung, CJ
;
電子工程學系及電子研究所
Theoretical derivations of the inelastic differential inverse mean free path (DIMFP) and inelastic mean free path (IMFP) for electrons crossing solid surfaces were made for different crossing angles and electron distances relative to the crossing point at the surface. Individual contributions from volume and surface excitations were separated and analyzed for electrons traveling inside and outside the solid. Extended Drude dielectric functions were employed to calculate the DIMFP and inverse IMFP for electrons incident into and escaping from Cu. It was found that the DIMFP and inverse IMFP for electrons moving inside the solid were approximately independent of crossing angle and position of electrons due to the compensation of volume and surface excitations. For electrons moving deep inside the solid, the DIMFP and inverse IMFP reduced to the values for electrons moving in an infinite solid. As electrons traveling in the vacuum, the DIMFP and inverse IMFP became greater for glancing incident and escaping angles since surface excitations were more probable. The surface excitation parameter (SEP) for electrons traveling in vacuum showed an angular dependence. The SEP of escaping electrons was found larger than that of incident electrons due to the attractive force exerted by the induced surface charges. The calculated SEP was found to follow a simple expression. (c) 2005 Elsevier B.V. All rights reserved.