Browsing by Issue Date, starting with "2004-11-22"

Now showing 1 - 20 of 69132

Influence of measuring environment on the electrical characteristics of pentacene-based thin film transistors
(2004-11-22)
Wang, YW
;
Cheng, HL
;
Wang, YK
;
Hu, TH
;
Ho, JC
This work concerns the electrical properties and carrier transport behavior of polycrystalline pentacene-based thin film transistors (TFTs) in air and high-vacuum environments. The transistor in a high vacuum outperforms that in air. The dependence of the field-effect mobility on the gate voltage and the drain voltage is considered. A potential barrier model is applied to estimate the trap density of the pentacene transistor. The determined trap density at the grain boundaries of the pentacene film in air exceeds that in a high vacuum. These results show that the increased trap concentration at the grain boundaries in ambient air limits carrier transport. (C) 2004 Elsevier B.V. All rights reserved.
Extraction of electrical mechanisms of low-dielectric constant material MSZ for interconnect applications (Vol 447, pg 516, 2004)
(2004-11-22)
Chang, TC
;
Yan, ST
;
Liu, PT
;
Lin, ZW
;
Aoki, H
Valence-band tunneling induced low frequency noise in ultrathin oxide (15 angstrom) n-type metal-oxide-semiconductor field effect transistors
(2004-11-22)
Wu, JW
;
You, JW
;
Ma, HC
;
Cheng, CC
;
Chang, CS
Low frequency flicker noise in n-type metal-oxide-semiconductor field effect transistors (n-MOSFETs) with 15 Angstrom gate oxide is investigated. A noise generation mechanism resulting from valence band tunneling is proposed. In strong inversion condition, valence-band electron tunneling takes place and results in the splitting of electron and hole quasi-Fermi levels in the channel. The excess low frequency noise is attributed to electron and hole recombination at interface traps between the two quasi-Fermi levels. Random telegraph signal in a small area device is characterized to support our model. (C) 2004 American Institute of Physics.
Effects of annealing temperature on electrical resistance of bonded n-GaAs wafers
(2004-11-22)
Liu, PC
;
Lu, CL
;
Wu, YCS
;
Cheng, JH
;
Ouyang, H
The electrical characteristics and microstructures of n-type (100) GaAs bonded interfaces were systematically investigated. Experimental results indicated that GaAs did not bond directly to itself, but via an amorphous oxide layer at 400 degreesC. When temperatures increased above 400 degreesC, the oxide bonded area declined and finally disappeared. Electrical resistance decreased with bonding temperature. However, the resistance increased with temperatures exceeding 850 degreesC. (C) 2004 American Institute of Physics.
Thermal and microwave assisted reactions of 2,5-disubstituted thienosultines with [60]fullerene: non-Kekule biradicals and self-sensitized oxygenation of the cycloadduct
(2004-11-22)
Chi, CC
;
Pai, IF
;
Chung, WS
;
應用化學系
;
Department of Applied Chemistry
Refluxing an o-dichlorobenzene solution of 2,5-disubstituted thienosultines 10a-f with [60]fullerene for 2-24 h gave both 1:1 and 2:1 cycloadducts in 37-79% isolated yields. The reaction was highly accelerated by microwave irradiation giving comparable yields of cycloadducts. Sultines 10a-f underwent cheletropic extrusion of SO2 to form the corresponding non-Kekule biradical intermediates 11a-f, which were subsequently trapped by [60]fullerene to form corresponding cycloadducts. The activation energy barriers (DeltaG(c)(not equal)) determined for the boat-to-boat inversion of these 4',5',6',7'-tetrahydrobenzo[c]thieno-[5',6':1,2][60]fullerene adducts 12a-f were found to be in the range of 13.5-14.8 kcal/mol. Unexpectedly, one of the monoadduct 12a was found to be labile when kept in air under ambient light. Two new products 15 (a sulfine-enone) and 16 (an endione) were isolated from the decomposed 12a and were found to derive from self-sensitized singlet oxygen reaction on the 2,5-dimethylthieno moiety of 12a. (C) 2004 Elsevier Ltd. All rights reserved.
Probing the microwave degradation mechanism of phenol-containing polymeric compounds by sample pretreatment and GC-MS analysis
(2004-11-22)
Chang, YC
;
Ko, FH
;
Ko, CJ
;
Chu, TC
;
材料科學與工程學系奈米科技碩博班
We have detected the volatile organic species obtained after microwave digestion of poly(hydroxystyrene) with nitric acid in closed vessels at various reaction temperatures by using headspace solid-phase microextraction (HS-SPME) and gas chromatography/mass spectrometry (GC-MS). We probed the digestion reaction by measuring the response of the detectable species - we detected a total of 20 volatile organic compounds - with respect to the temperature over the range from room temperature to 80 degreesC. These compounds can be classified into alkane, alkanol, and aromatic species. The alkane species decreased monotonically, whereas the alkanol and aromatic compounds first increased and then decreased, as the digestion temperature increased. We have established the degradation mechanisms, which involve bond scission, recombination, adduct formation, and ring opening, on the basis of product analyses and bond length simulations. (C) 2004 Elsevier B.V. All rights reserved.
好一場文學野宴(上)
(2004-11-23)
孫瑋芒
好一場文學野宴(下)
(2004-11-24)
廖玉蕙
Direct generation of optical bottle beams from a tightly focused end-pumped solid-state laser
(2004-11-29)
Tai, PT
;
Hsieh, WF
;
Chen, CH
;
光電工程學系
;
Department of Photonics
We demonstrate that various optical bottle beams can be directly generated from a tightly focused end-pumped Nd:YVO4 laser. By controlling the size of pump beam and intracavity aperture in a planoconcave cavity, we obtain well contrasting optical bottles with semiconfocal, 1/3-, and 1/5-degenerate cavity configurations. These beams result, respectively, from the superposition of the fundamental mode and the corresponding lowest degenerate transverse eigenmode, which is in-phase at their beam waists. Unlike that of our previous simulation model, this new observation is universal; it is suitable for any kind of gain media in tightly end-pumped lasers. (C) 2004 Optical Society of America.
Simulation of lid-driven cavity flows by parallel lattice Boltzmann method using multi-relaxation-time scheme
(2004-11-30)
Wu, JS
;
Shao, YL
;
機械工程學系
;
Department of Mechanical Engineering
Two-dimensional near-incompressible steady lid-driven cavity flows (Re= 100-7,500) are Simulated using multi-relaxation-time (MRT) model in the parallel lattice Boltzmann BGK Bhatnager-GrossKrook method (LBGK). Results are compared with those using single-relaxation-time (SRT) model in the LBGK method and previous simulation data using Navier-Stokes equations for the same flow conditions. Effects of variation of relaxation parameters in the MRT model, effects of number of the lattice points, improved computational convergence and reduced spatial oscillations of solution near Geometrically singular points in the flow field using LBGK method due to MRT model are highlighted in the study. In summary, lattice Boltzmann method using MRT model introduces much less spatial oscillations near geometrical singular points, which is important for the successful simulation of higher Reynolds number flows. Copyright (C) 2004 John Wiley Sons, Ltd.
低溫多晶矽薄膜電晶體主動層之雷射再結晶方法
(2004-12-01)
葉清發
;
陳添富
;
羅正忠
本發明係一種低溫多晶矽薄膜電晶體主動層之雷射再結晶方法，其係利用具單一方向性之乾式蝕刻在薄膜電晶體主動層側壁覆蓋一間距矽(poly–spacer)，該間距矽(poly–spacer)提供了一雷射側向再結晶機制與可防止雷射再結晶後主動層微縮或剝落現象，可使通道內之矽晶粒變大但不需額外光罩，如此同時提升元件特性、提高元件均勻度與節省製程成本，此技術在現今低溫多晶矽薄膜電晶體(LTPS–TFTs)領域中將會是一項關鍵技術。
An optimal interpolated FIR echo canceller for digital subscriber lines
(2004-12-01)
Lin, SS
;
Wu, WR
;
電信工程研究所
;
Institute of Communications Engineering
An adaptive interpolated FIR (IFIR) echo canceller was recently proposed for xDSL applications. This canceller consists of an FIR filter, an IFIR filter, and a tap-weight overlapping and nulling scheme. The FIR filter is used to cancel the short and rapidly changing head echo while the IFIR filter is used to cancel the long and slowly decaying tail echo. This echo canceller, which inherits the stable characteristics of the conventional FIR filter, requires low computational complexity. It is well known that the interpolation filter for an IFIR filter has great influence on the interpolated result. In this paper, a least-squares method is proposed to obtain optimal interpolation filters such that the performance of the IFIR echo canceller can be further improved. Simulations with a wide variety of loop topologies show that the optimal IFIR echo canceller can effectively cancel the echo up to 73.0 dB (for an SHDSL system). About 57% complexity reduction can be achieved compared to a conventional FIR filter.
Diagnosability of t-connected networks and product networks under the comparison diagnosis model
(2004-12-01)
Chang, CP
;
Lai, PL
;
Tan, JJM
;
Hsu, LH
;
資訊工程學系
Diagnosability is an important factor in measuring the reliability of an interconnection network, while the (node) connectivity is used to measure the fault tolerance of an interconnection network. We observe that there is a close relationship between the connectivity and the diagnosability. According to our results, a t-regular and t-connected network with at least 2t + 3 nodes is t-diagnosable. Furthermore, the diagnosability of the product networks is also investigated in this work. The product networks, including hypercube, mesh, and tori, comprise very important classes of interconnection networks. Herein, different combinations of t-diagnosable and t-connected are employed to study the diagnosability of the product networks.
Single mode 1.3 mu m InGaAsN/GaAs quantum well vertical cavity surface emitting lasers grown by molecular beam epitaxy
(2004-12-01)
Hsiao, RS
;
Wang, JS
;
Lin, KF
;
Wei, L
;
Liu, HY
The growth by molecular-beam-epitaxy of high-quality 1.3 mum InGaAsN/GaAs quantum wells (QW) intra-cavity contacted vertical cavity surface emitting lasers (VCSELs) was demonstrated. Low-temperature growth, which suppresses the phase separation significantly improves material quality in the active region. Room-temperature continuous wave (RT-CW) single mode output power of 0.75 mW with an initial slope efficiency of 0.17 W/A and a side mode suppression ratio of 40 dB at a lasing wavelength of as long as 1304 nm were obtained.
A resolvable r x c grid-block packing and its application to DNA library screening
(2004-12-01)
Mutoh, Y
;
Jimbo, M
;
Fu, HL
;
應用數學系
;
Department of Applied Mathematics
For a nu-set V, let A be a collection of r x c arrays with elements in V. A pair (V, A) is called an r x c grid-block packing if every two distinct points i and j in V occur together at most once in the same row or in the same column of arrays in A. And an r x c grid-block packing (V, A) is said to be resolvable if the collection of arrays A can be partitioned into sub-classes R-1, R-2,..., R-t such that every point of V is contained in precisely one array of each class. These packings have originated from the use of DNA library screening. In this paper, we give some constructions of resolvable r x c grid-block packings and give a brief survey of their application to DNA library screening.
Nanoparticles of Pb-Bi eutectic nucleation and growth on alumina template
(2004-12-01)
Chen, CC
;
Kuo, CG
;
Chen, JH
;
Chao, CG
;
材料科學與工程學系
A novel and convenient method of thermo-immersion was used to fabricate of a large of lead-bismuth (Pb-Bi) eutectic nanoparticles on an uniform size anodic aluminum oxide (AAO) template. The AAO with a 60 nm pore diameter was used as a template for nanoparticles nucleation and growth. Both Pb-Bi and AAO were placed in a glass tube in vacuum at 10(-6) Torr, controlled by a molecular turbo pump then heated up to the melting point of the alloy. Nanoparticles nucleated and grew on the AAO template when the molten Pb-Bi solidified. The nanoparticles nucleated on the pore corners of the AAO template initially, grew simultaneously and assembled into a big nanoparticle on top of the AAO template later. Additionally, the size diameters of the initial nanoparticles were approximately 15 nm on the pore corners of the AAO template, and 80 nm when the initial nanoparticles formed a large nanoparticle. Latent heat was released when the molten Pb-Bi solidified to form nanoparticles. The size diameters distribution of nanoparticles was observed by scanning electron microscopy (SEM) such that, the diameters of the nanoparticles were 80 nm on top of the AAO template, and 200 nm in depths of the concave.
Improving spin-coating process using altered cover design
(2004-12-01)
Cheng, CM
;
Chen, RH
;
機械工程學系
;
Department of Mechanical Engineering
A novel work chamber cover design for a spin coater that can reduce the effect of airflow on spin coating is presented. The experimental results reveal that superior uniformity and film area can be obtained by utilizing the modified design instead of the conventional design.
Growth of ZnO nanowires without catalyst on porous silicon
(2004-12-01)
Chang, CC
;
Chang, CS
;
光電工程學系
;
Department of Photonics
Porous silicon (PS) technology is, for the first time, used to grow ZnO nanowires on the surface of a PS substrate with a rough morphology without any catalyst. The characteristics of these nanowires were investigated by field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy dispersive X-ray (EDX), grazing-angle X-ray diffraction (XRD) and photoluminescence (PL) measurements. Zn vapor condenses easily on the PS surface and forms a wetting layer, but not on the flat Si surface. The PS surface provides a rough surface morphology to form a wetting layer by decreasing the surface energy so that ZnO nanowires can grow without any catalyst. The Zn-rich composition changed during growth; the ratio of zinc to oxygen was near to one at the top part of the nanowires. The probable growth mechanism was the vapor-solid (VS) process. In principle, the selective growth of ZnO nanowires on Si-base devices for optoelectronic application is possible.
Chaos anticontrol and synchronization of three time scales brushless DC motor system
(2004-12-01)
Ge, ZM
;
Cheng, JW
;
Chen, YS
;
機械工程學系
;
Department of Mechanical Engineering
Chaos anticontrol of three time scale brushless dc motors and chaos synchronization of different order systems are studied. Nondimensional dynamic equations of three time scale brushless DC motor system are presented. Using numerical results, such as phase diagram, bifurcation diagram, and Lyapunov exponent, periodic and chaotic motions can be observed. By adding constant term, periodic square wave, the periodic triangle wave, the periodic sawtooth wave, and kxx term, to achieve anticontrol of chaotic or periodic systems, it is found that more chaotic phenomena of the system can be observed. Then, by coupled terms and linearization of error dynamics, we obtain the partial synchronization of two different order systems, i.e. brushless DC motor system and rate gyroscope system. (C) 2004 Elsevier Ltd. All rights reserved.
Oxidation of TNT by photo-Fenton process
(2004-12-01)
Liou, MJ
;
Lu, MC
;
Chen, JN
;
環境工程研究所
;
Institute of Environmental Engineering
A series of photo-Fenton reactions have been performed for the degradation of 2,4,6-trinitrotoluene (TNT) in a 4.2-1 reactor. The degradation reaction rate of TNT followed a pseudo-first-order behavior; and the rate constants for 2.4 mW cm(-2) UV only, 2.4 mWcm(-2)UV/H2O2, Fenton, photo-Fenton (2.4 mW cm(-2)) and photo-Fenton (4.7 mW cm(-2)) were 0.002 min(-1), 0.007 min(-1), 0.014 min(-1), 0.025 min(-1) and 0.037 min(-1), respectively. Increasing the intensity of UV light, and the concentrations of ferrous ions and hydrogen peroxide promoted the oxidation rate under the experimental conditions in this study. The weighting factor (f), the Fe(II)-promoted efficiency (r) and the promoted-UV light efficiency (p) were calculated to clarify their effects on the TNT oxidation. Moreover, the inhibition effect of hydroxyl radical was also observed in both Fenton and photo-Fenton oxidation when the concentration of Fe(II) were higher than 2.88 mM. Solid phase micro-extraction was first applied to the separation of the organic byproducts from TNT oxidation. GC/MS was employed to identify the byproducts during the Fenton and photo-Fenton oxidation of TNT. These compounds were clarified as 1,3,5-trinitrobenzene, 1-methyl-2,4-dinitrobenzene 2,5-dinitrobenzoic acid and 1,3-dinitrobenzene. By these byproducts, the mechanisms of the methyl group oxidation, decarboxylation, aromatic ring breakage, and hydrolysis can be recognized and demonstrated. The pathway of TNT oxidation by photo-Fenton process was also proposed in this study. (C) 2004 Elsevier Ltd. All rights reserved.