Browsing by Issue Date, starting with "2005-11-01"

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A source-follower type analog buffer using poly-Si TFTs with large design windows
(2005-11-01)
Tai, YH
;
Pai, CC
;
Chen, BT
;
Cheng, HC
;
電子工程學系及電子研究所
New simple source follower circuits using low-temperature polycrystalline silicon thin-film transistors (LTPS-TFTs) as analog buffers for the integrated data driver circuit of active-matrix liquid crystal displays and active-matrix light emitting diodes are discussed. In addition to the threshold voltage difference of driving TFTs, the unsaturated of output voltage arisen from the significant subthreshold current will also result in the difficulty of the buffer circuit design. The proposed circuit is capable of minimizing the variation from both the signal timing and the device characteristics.
Poly(p-phenylenevinylene) presenting pendent pentaphenylene dendron groups for light-emitting diodes
(2005-11-01)
Tseng, YH
;
Wu, FI
;
Shih, PI
;
Shu, CF
;
應用化學系
We have synthesized, using the Gilch method, a novel poly(p-phenylenevinylene) derivative (PPV-PP) containing two pendent pentaphenylene dendritic wedges, and have characterized its structure and properties. The incorporated side chain pentaphenylene dendrons serve as solubilizing groups, prevent pi-stacking interactions from occurring between the polymer main chains, and suppress the formation of excimers in the solid state. Photoluminescence studies indicate that efficient intramolecular energy transfer occurred from the photoexcited pentaphenylene groups to the poly(p-phenylenevinylene) backbone. The polymer film exhibits a maximum emission at 510 nm and had a photoluminescence efficiency of 46%, which is similar to that measured in dilute solution. The photoluminescence spectra remained almost unchanged after thermal annealing at 150 degrees]C for 20 h, and displayed inhibited excimer formation. Polymer light-emitting diodes that we fabricated in the configuration ITO/PEDOT/PPV-PP/Mg:Ag/Ag exhibited a maximum emission peak at 513 nm, corresponding to the green region [x = 0.30 and y = 0.62 in the Commission Internationale de L'Eclairage (CIE) chromaticity coordinates]. The maximum brightness and maximum luminance efficiency were 1562 cd/m(2) and 1.93 cd/A, respectively. (c) 2005 Wiley Periodicals, Inc.
Neural-network-based adaptive hybrid-reflectance model for 3-D surface reconstruction
(2005-11-01)
Lin, CT
;
Cheng, WC
;
Liang, SF
;
生物科技學系
;
資訊工程學系
This paper proposes a novel neural-network-based adaptive hybrid-reflectance three-dimensional (3-D) surface reconstruction model. The neural network automatically combines the diffuse and specular components into a hybrid model. The proposed model considers the characteristics of each point and the variant albedo to prevent the reconstructed surface from being distorted. The neural network inputs are the pixel values of the two-dimensional images to be reconstructed. The normal vectors of the surface can then be obtained from the output of the neural network after supervised learning, where the illuminant direction does not have to be known in advance. Finally, the obtained normal vectors are applied to enforce integrability when reconstructing 3-D objects. Facial images and images of other general objects were used to test the proposed approach. The experimental results demonstrate that the proposed neural-network-based adaptive hybrid-reflectance model can be successfully applied to objects generally and perform 3-D surface reconstruction better than some existing approaches.
A novel wafer reclaim method for amorphous SiC and carbon doped oxide films
(2005-11-01)
Tsui, BY
;
Fang, KL
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Amorphous SiC (a-SiC) films are the most promising dielectric diffusion barriers to replace silicon nitride in Cu-interconnect technology. However, reclaim of wafers with a-SiC films is a challenge issue for mass production. In this paper, a novel wafer reclaim method is proposed. It is observed that a-SiC can be oxidized to SiO2 in both dry O-2 and steam ambients at temperatures as low as 550 degrees C. The oxidation mechanism can be described by the Deal-Grove model that is traditionally used to describe oxidation of Si. Experiments prove that the oxidation process is clean and uniform. It is also observed that carbon doped oxide (CDO) films can be oxidized easily, too. Therefore, oxidation followed by HF etching could be a universal process to reclaim wafers deposited with a-SiC or CDO films. Since the oxidation rate of Si substrates at medium temperatures is much lower than that of a-SiC and CDO films, the oxidation process is virtually self-limiting. Compared with a traditional reclaim method based on wafer polishing, this universal oxidation-etching method exhibits great benefits in terms of low cost, high throughput, and the ability to perform nearly unlimited numbers of reclaim cycles.
Selective growth of horizontally-oriented carbon nanotube bridges on patterned silicon wafers by electroless plating Ni catalysts
(2005-11-01)
Lin, CC
;
Chen, PL
;
Lin, CT
;
Kuo, CT
;
材料科學與工程學系
The main purpose of this research was to develop an Integrated Circuit compatible process to grow the horizontally-oriented carbon nanotubes (CNTs) across the trenches of the patterned Si wafer, which was produced by conventional photolithography technique. The selectivity of tile process is based oil the difference ill electrical conductivity between amorphous silicon (a:Si) and silicon nitride (Si3N4), where the catalyst can be much easier deposited by electroless plating on the a:Si part of the pattern. The selectivity is also based oil greater chemical reactivity of the catalyst with a:Si to form silicides, instead of with Si3N4. Furthermore, the Si3N4 barrier layer of the pattern was designed oil top of tile a:Si layer to guide the growth of CNTs in horizontal direction to bridge tile trenches of tile pattern. The as-deposited catalysts were examined by Auger electron spectroscopy (AES). The catalyst-coated pattern was pretreated in hydrogen plasnia and followed by CNT growth in a microwave plasina chemical vapor deposition (MPCVD) system. The CNT bridges were characterized by scanning electron microscopy (SEM), transmission electron rnicroscopy (TEM), high-resolution TEM (HRTEM), and I-V measurements. Under tile present deposition conditions, TEM and HRTEJM examinations indicate that the deposited nanostructures are bamboo-like InUltiwalled carbon nanOtLibes (MWNTs) with a wall thickness of 20 similar to 30 graphene layers. Electrical conductivity of the as-deposited MWNTs call be greatly improved by subjecting to 760 degrees C heat treatment under nitrogen atmosphere. The results demonstrate that the amounts of' CNTs and bridges are tunable with tile Ni catalyst plating time. Under the present experimental configuration and at a catalyst plating time of 20 s, countable numbers of bridges call be obtained, which are selectively and horizontally grown oil the areas of the pattern with Ni catalyst. This process call be a step approaching the application of CNTs in electronic devices. (c) 2005 Elsevier B.V. All rights reserved.
Transverse patterns and length-scale selection in vertical-cavity surface-emitting lasers with a large square aperture
(2005-11-01)
Schulz-Ruhtenberg, M
;
Babushkin, IV
;
Loiko, NA
;
Ackemann, T
;
Huang, KF
The length-scale selection in complex emission patterns spontaneously arising in broad-area vertical-cavity surface-emitting lasers is studied experimentally. The wavenumbers of individual tilted wave modes show a square-root-like dependence on the detuning between emission frequency and longitudinal cavity resonance, in accordance with theoretical expectations. The absolute values of the wavenumbers are in good qualitative agreement with calculations taking into account the reflection properties of the Bragg reflectors and dispersion.
可同時量測光學晶體厚度及光軸之影像式偏極光量測方法
(2005-11-01)
黃中垚
;
李建立
本發明提供一種可同時量測光學晶體厚度及光軸之影像式光學量測方法，其係利用同一偏光儀架構先進行析光片旋轉量測，以透過析光片連續變化之不同方位角來取得相對應之一系列的光強度變化影像，並將該等影像擬合以得到晶體薄膜之光軸投影在薄膜平面之投影光軸指向，接著再進行樣品旋轉量測，以連續調整偏極光對於薄膜之入射角，進而測得薄膜光軸在三維空間的指向和厚度之二維分佈。因此本發明在僅使用一量測架構之前提下，可同時測得光學晶體之厚度及其光軸指向，並可達成降低量測成本、經濟、量測方便及測值精確等功效。
Fabrication of narrow-band self-filtering GaAs photodetector by epitaxy
(2005-11-01)
Shie, JS
;
Hwang, TSD
;
光電工程學系
;
Department of Photonics
A narrow-band self-filtering (NBSF) GaAs photodiode has been fabricated by the LPE technique, where epilayers of high-low-high N doping were grown on a P-type substrate. By proper control of the thickness and doping concentration of each layer, it can be demonstrated that the fabricated NBSF detector has a spectral bandwidth as narrow as 315 angstrom at 880 nm peak wavelength. This means over 98% of the blue-side light is suppressible, indicating that the NBSF photodetector is a useful device for many applications where the suppression of high background light is necessary. (c) 2005 American Institute of Physics.
Chromatic-dispersion monitoring using an optical delay-and-add filter
(2005-11-01)
Tsai, KT
;
Way, WI
;
電信工程研究所
;
Institute of Communications Engineering
A novel postdetection method based on an optical delay-and-add filter (DAF) is proposed for dispersion monitoring at 40 Gb/s or beyond. The proposed method can be used with or without a pilot tone and works well even when there exists a residual chirp due to the finite direct current (DC) extinction ratio of a Mach-Zehnder (MZ) modulator or self-phase modulation (SPM). Several modulation formats, including conventional nonreturn to zero (NRZ), return to zero (RZ), carrier-suppressed RZ (CSRZ), RZ differential phase shift keying (RZ-DPSK), and CSRZ-DPSK are used to numerically demonstrate the feasibility of this technique without using a pilot tone.
A closed-form integral model of spiral inductor using the Kramers-Kronig relations
(2005-11-01)
Chen, CC
;
Huang, JK
;
Cheng, YT
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
In this letter, a closed-form integral model is presented for the rectangular micromachined spiral inductor. The Kramers-Kronig relations provide an elegant theory to describe the inductor behavior without having complicated geometric analysis. Simulation and measurement results validate that the model can provide satisfactory prediction to the inductance of on-chip freely-suspended spiral inductors. Meanwhile, unlike conventional Greenhouse-based formulations, the self-resonant frequency of inductor can be predicted using the integral model.
Growth mechanism and properties of the well-aligned-carbon-coated Si nanocones by MPCVD
(2005-11-01)
Chuang, PK
;
Teng, IJ
;
Wang, WH
;
Kuo, CT
;
材料科學與工程學系
in order to clarify the possibility to form Si nanocones under the same gas sources (CH4 and H,) and deposition system (microwave plasma chemical vapor deposition (MPCVD)), a process were successfully developed to synthesize the well-aligned amorphous carbon-coated Si nanocones (a:C-SNCs), and their growth mechanism is proposed. This process includes depositing 10 nm Co-catalyst on Si wafer by physical vapor deposition (PVD) and then followed by H-plasma pretreatment to form Co nanoparticles. The pretreated specimens were then used to synthesize various nanostructures under a higher negative Substrate bias. The deposited nanostructures and their compositions were characterized by SEM, HRTEM, ED, EDS and Raman spectroscopy. The results indicate that the most important parameters for forming a:C-SNCs include a lower CH4/H-2 ratio, a higher negative substrate bias and assistance of the carbon-soluble nano-sized catalysts, such as Co. Under a higher enough negative substrate bias (>= 240 V), the etching rates of the catalyst particles and the substrate by the positive species are greater than the carbon deposition rate; a:C-SNCs can be formed. We propose that the cone shape of the nanostructures is essentially resulted from a progressive reduction in catalyst particle sizes under the conditions of higher etching rate than deposition rate on the catalyst surfaces, which may be partially due to a reduction in the Co melting temperature by the presence of carbon in the Co matrix. This mechanism is supported by the facts that a:C-SNCs find no catalysts or very small catalysts on the tips; the catalyst sizes show no significant reduction in sizes after the same a:C-SNCs deposition conditions except no presence of carbon; the diameter of the cone base has no significant differences in size as the original catalyst size after H-plasma pretreatment. Our mechanism gives the guideline to form the nanocone structures by MPCVD with same gas sources (CH4 and H-2). (c) 2005 Published by Elsevier B.V.
Variation of group velocity and complete bandgaps in two-dimensional photonic crystals with drilling holes into the dielectric rods
(2005-11-01)
Liu, WL
;
Yang, TJ
;
電子物理學系
;
Department of Electrophysics
Two-dimensional square lattices of square cross-section dielectric rods in air, designed with an air hole drilled into each square rod, are studied theoretically. By adjusting the shift of the hole position in the square rod in each unit cell, the dielectric distribution of the square rod will be modified. A sizable complete band gap occurs for certain structural parameters and exhibits very flat photonic bands near such gap edge. which resulting in a sharp peak of density of states. In addition, the zero or small group velocities are observed in a broad region of k-space. This structure can be fabricated with materials widely used today and opens a fascinating area for applications in optoelectric devices. (c) 2005 Elsevier B.V. All rights reserved.
Effects of different n-electrode patterns on optical characteristics of large-area p-side-down InGaN light-emitting diodes fabricated by laser lift-off
(2005-11-01)
Chu, JT
;
Kao, CC
;
Huang, HW
;
Liang, WD
;
Chu, CF
Large-area p-side-down InGaN light-emitting diodes (LEDs) 1000 x 1000 mu m(2) in size have been fabricated by laser lift-off (LLO). The p-side-down LEDs with different geometric patterns of n-electrodes were fabricated to investigate electrode pattern-dependent optical characteristics. The current crowding effect was observed in the large-area p-side-down InGaN LLO-LEDs. A LED with a well-designed n-electrode pattern shows a uniform distribution of light emission and a higher output power due to uniform current spreading. The output power saturation induced by the current crowding effect was investigated. In the absence of a transparent contact layer for current spreading, the n-electrode pattern has a marked influence on the current distribution and the consequent light output power of the large-area p-side-down LEDs.
Removal of high concentration of NH3 and coexistent H2S by biological activated carbon (BAC) biotrickling filter
(2005-11-01)
Chung, YC
;
Lin, YY
;
Tseng, CP
;
生物科技學系
;
Department of Biological Science and Technology
High efficiency of NH3 and H2S removal from waste gases was achieved by the biotrickling filter. Granular activated carbon (GAC), inoculated with Arthrobacter oxydans CH8 for NH3 removal and Pseudomonas putida CH11 for H2S removal, was used as packing material. Under conditions in which 100% H2S was removed, extensive tests to eliminate high concentrations of NH3 emission-including removal characteristics, removal efficiency, and removal capacity of the system-were performed. The results of the Bed Depth Service Time (BDST) experiment suggested that physical adsorption of NH3 gas by GAC was responsible for the first 10 days, after which NH3 gas was biodegraded by inoculated microorganisms. The dynamic steady state between physical adsorption and biodegradation was about two weeks. After the system achieved equilibrium, the BAC biotrickling filter exhibited high adaptation to shock loading, elevated temperature, and flow rate. Greater than 96% removal efficiency for NH3 was achieved during the 140-day operating period when inlet H2S loading was maintained at 6.25 g-S/m(3)/h. During the operating period, the pH varied between 6.5 and 8.0 after the physical adsorption stage, and no acidification or alkalinity was observed. The results also demonstrated that NH3 removal was not affected by the coexistence of H2S while gas retention time was the key factor in system performance. The retention time of at least 65 s is required to obtain a greater than 95% NH3 removal efficiency. The critical loading of NH3 for the system was 4.2 g-N/m(3)/h, and the maximal loading was 16.2 g-N/m(3)/h. The results of this study could be used as a guide for further design and operation of industrial-scale systems. (c) 2005 Elsevier Ltd. All rights reserved.
A CMOS low-noise amplifier for ultra wideband wireless applications
(2005-11-01)
Chou, MF
;
Wuen, WS
;
Wu, CC
;
Wen, KA
;
Chang, CY
A CMOS low noise amplifier (LNA) for low-power ultrawideband (UWB) wireless applications is presented. To achieve low power consumption and wide operating bandwidth, the proposed LNA employing stagger tuning technique consists of two stacked common-source stages with different resonant frequencies. This work is implemented in 0.18-mu m CMOS process and shows a 2.4-9.4-GHz bandwidth. The amplifier provides a maximum forward gain (S-21) of 10.9 dB while drawing 7.1 mW from a 1.8-V supply. A noise figure as low as 4.1 dB and an IIP3 of -3.5 dBm have been demonstrated.
System structure and contour tracking for a hybrid motion platform
(2005-11-01)
Lue, CW
;
Cheng, YM
;
Chin, JH
;
機械工程學系
;
Department of Mechanical Engineering
This work investigates the spatial contour tracking on a new kind of motion platform that is constructed by extending the parallel platform with a proven planar motion table. Multi-axis cross-coupled tracking control schemes were developed on the basis of this hybrid structured Stewart platform, which formed a 5-axis working machine. A framework for the functions of this system was established. Roadmap for further development that leads to a highly versatile and efficient precision motion platform was made.
Hamiltonian and measuring time for analog quantum search
(2005-11-01)
Hsieh, JY
;
Li, CM
;
Chuu, DS
;
電子物理學系
;
Department of Electrophysics
In this work, an analog analogue of Grover's quantum search algorithm was studied. A generalized Hamiltonian driving the evolution of a quantum state in the analog search system was derived. Equations relating all parameters considered in the present problem were given according to the required maximal probability for finding the marked state. Using these equations, both the measuring time and the system energy gap suitable for a quantum search with or without certainty can thus be evaluated. Moreover, the reduction of the searching probability caused by a random and uncontrollable phase error for an initial state has been investigated. It was shown that in an efficient quantum search computation, the measuring time should be proportional to the square root of the size of the database.
Performance comparisons of external modulated hybrid analog-digital signals in electrical and optical domains
(2005-11-01)
Peng, WR
;
Peng, PC
;
Hsueh, YT
;
Feng, KM
;
Chi, S
A multipurpose network which integrates the functionalities of single radio channel and baseband data distribution has been proposed recently. In this letter, we further propose and compare two possible combination schemes which combine multiple radio channel and single digital baseband data in electrical and optical domains. Linearity of multiple radio channels and performance of digital baseband data are studied in this externally modulated hybrid analog-digital link. It is found that signals combined in the optical domain, while with higher cost, will outperform that in the electrical domain on the carrier-to-noise and distortion ratio. In addition, the baseband data performance is also improved with optical combining scheme since the optimum required modulation index is lower.
On the development of a computer-assisted testing system with genetic test sheet-generating approach
(2005-11-01)
Hwang, GJ
;
Lin, BMT
;
Tseng, HH
;
Lin, TL
;
資訊管理與財務金融系註：原資管所+財金所
Since the last decade, computer-assisted testing has proven to be an efficient and effective way to evaluating students' learning status such that proper tutoring strategies can be adopted to improve-their learning performance. A good test will not only help the instructor evaluate the learning status of the students, but also facilitate the diagnosis of the problems embedded in the students' learning process. One of the most important and challenging issues in conducting a good test is the construction of test sheets that can meet various assessment requirements. A previous study has indicated that selecting test items to best fit multiple assessment requirements can be formulated as a mixed integer programming model. The problem is known to be NP-hard in the literature and, hence, computational challenges hinder the development of efficient solution methods. As a sequel, we instead seek quality approximate solutions in a reasonable time. Two approximation methods based upon a genetic approach are developed. Statistics from a series of computational experiments indicate that our approach is able to efficiently generate near-optimal combinations of test items that satisfy the specified requirements or constraints.
Rapid and simple automatic trapping-force calibration system for optical tweezers
(2005-11-01)
Chang, BJ
;
Hsu, L
;
Chi, S
;
電子物理學系
;
光電工程學系
The automation of a rapid and simple trapping-force calibration system is desired for optical tweezers to measure biological forces. One simple calibration method, the water-dragging-force method, is to calibrate the trapping force against a given water dragging force with an image-processing technique. However, the conventional image-processing technique is too slow because of the time it takes for image recording, transferring, storing, and retrieving. The pattern recognition technique of our automated calibration method is rapid and simple, because it directly processes the image signal without recording, storing, and retrieving any image. In an experiment, we have combined the dragging force method with the real-time pattern recognition technique to calibrate the relationship between the trapping force at a given laser power and a displacement of a bead. We demonstrate the calibration results of the trapping forces on two target beads 10 and 6.2 mu m in diameter, separately, at two laser powers, 5 and 10 mW. Each calibration procedure is finished in 5 min at a pattern recognition rate of 10 Hz with a spatial resolution of 75 nm. We believe that this technique is reliable and rapid enough to be applied to biological force measurement. (c) 2005 Society of Photo-Optical Instrumentation Engineers.