Browsing by Issue Date, starting with "2010-07-23"

Now showing 1 - 20 of 45644

Site-controlled self-assembled InAs quantum dots grown on GaAs substrates
(2010-07-23)
Lin, Shih-Yen
;
Tseng, Chi-Che
;
Chung, Tung-Hsun
;
Liao, Wen-Hsuan
;
Chen, Shu-Han
Atomically-flat surfaces are obtained after thin GaAsSb buffer layer growth on GaAs substrates with regular-distributed nano-holes formed after oxide desorption of the local atomic-force-microscopy anode oxidation. Different from the samples with GaAsSb buffer layers, increasing surface root-mean-square roughness is observed for the GaAs-buffered samples with increasing GaAs buffer layer thickness. The phenomenon is attributed to the enhanced adatom migration resulting from the incorporation of Sb atoms. By using the substrates with nano-holes after buffer layer growth, site-controlled self-assembled InAs quantum dots (QDs) are observed with the deposition of a below-critical-thickness InAs coverage of 1.3 monolayer (ML).
Highly stable precursor solution containing ZnO nanoparticles for the preparation of ZnO thin film transistors
(2010-07-23)
Huang, Heh-Chang
;
Hsieh, Tsung-Eong
;
材料科學與工程學系
;
Department of Materials Science and Engineering
ZnO particles with an average size of about 5 nm were prepared via a sol-gel chemical route and the silane coupling agent, (3-glycidyloxypropyl)-trimethoxysilane (GPTS), was adopted to enhance the dispersion of the ZnO nanoparticles in ethyl glycol (EG) solution. A ZnO surface potential as high as 66 mV was observed and a sedimentation test showed that the ZnO precursor solution remains transparent for six months of storage, elucidating the success of surface modification on ZnO nanoparticles. The ZnO thin films were then prepared by spin coating the precursor solution on a Si wafer and annealing treatments at temperatures up to 500 degrees C were performed for subsequent preparation of ZnO thin film transistors (TFTs). Microstructure characterization revealed that the coalescence of ZnO nanoparticles occurs at temperatures as low as 200 degrees C to result in a highly uniform, nearly pore-free layer. However, annealing at higher temperatures was required to remove organic residues in the ZnO layer for satisfactory device performance. The 500 degrees C-annealed ZnO TFT sample exhibited the best electrical properties with on/off ratio = 10(5), threshold voltage = 17.1 V and mobility (mu) = 0.104 cm(2) V(-1) s(-1).
Molecular characterization of the PhoPQ-PmrD-PmrAB mediated pathway regulating polymyxin B resistance in Klebsiella pneumoniae CG43
(2010-07-24)
Cheng, Hsin-Yao
;
Chen, Yi-Fong
;
Peng, Hwei-Ling
;
生物科技學系
;
分子醫學與生物工程研究所
Background: The cationic peptide antibiotic polymyxin has recently been reevaluated in the treatment of severe infections caused by gram negative bacteria. Methods: In this study, the genetic determinants for capsular polysaccharide level and lipopolysaccharide modification involved in polymyxin B resistance of the opportunistic pathogen Klebsiella pneumoniae were characterized. The expressional control of the genes responsible for the resistance was assessed by a LacZ reporter system. The PmrD connector-mediated regulation for the expression of pmr genes involved in polymyxin B resistance was also demonstrated by DNA EMSA, two-hybrid analysis and in vitro phosphor-transfer assay. Results: Deletion of the rcsB, which encoded an activator for the production of capsular polysaccharide, had a minor effect on K. pneumoniae resistance to polymyxin B. On the other hand, deletion of ugd or pmrF gene resulted in a drastic reduction of the resistance. The polymyxin B resistance was shown to be regulated by the two-component response regulators PhoP and PmrA at low magnesium and high iron, respectively. Similar to the control identified in Salmonella, expression of pmrD in K. pneumoniae was dependent on PhoP, the activated PmrD would then bind to PmrA to prolong the phosphorylation state of the PmrA, and eventually turn on the expression of pmr for the resistance to polymyxin B. Conclusions: The study reports a role of the capsular polysaccharide level and the pmr genes for K. pneumoniae resistance to polymyxin B. The PmrD connector-mediated pathway in governing the regulation of pmr expression was demonstrated. In comparison to the pmr regulation in Salmonella, PhoP in K. pneumoniae plays a major regulatory role in polymyxin B resistance.
The influences of surface treatment and gas annealing conditions on the inversion behaviors of the atomic-layer-deposition Al2O3/n-In0.53Ga0.47As metal-oxide-semiconductor capacitor
(2010-07-26)
Trinh, H. D.
;
Chang, E. Y.
;
Wu, P. W.
;
Wong, Y. Y.
;
Chang, C. T.
The inversion behaviors of atomic-layer-deposition Al2O3/n-In0.53Ga0.47As metal-oxide-semiconductor capacitors are studied by various surface treatments and postdeposition annealing using different gases. By using the combination of wet sulfide and dry trimethyl aluminum surface treatment along with pure hydrogen annealing, a strong inversion capacitance-voltage (C-V) response is observed, indicating a remarkable reduction in interface trap state density (D-it) at lower half-part of In0.53Ga0.47As band gap. This low D-it was confirmed by the temperature independent C-V stretch-out and horizontal C-V curves. The x-ray photoelectron spectroscopy spectra further confirm the effectiveness of hydrogen annealing on the reduction of native oxides. (C) 2010 American Institute of Physics. [doi:10.1063/1.3467813]
Oxygen vacancy estimation of high k metal gate using thermal dynamic model
(2010-07-26)
Chang, H. L.
;
Liang, M. S.
;
材料科學與工程學系
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Department of Materials Science and Engineering
Oxygen vacancies are electronic defects in materials. In a metal oxide system, the distribution of such vacancies is determined by the oxygen affinity. This study predicts the oxygen vacancy concentration in a high-k/metal gate system using a developed thermal dynamic model. A system with Ti:N=2 has a 200 mV lower flat band voltage than an N rich metal. The Gibbs free energy of formation of oxygen vacancies, similar to 0.5 eV, is derived from flab band voltage shifts and created neutral oxygen vacancy. The oxygen vacancy model based on estimating thermal dynamics is proposed. (C) 2010 American Institute of Physics. [doi:10.1063/1.3473772]
Carrier dynamics in isoelectronic ZnSe(1-x)O(x) semiconductors
(2010-07-26)
Lin, Y. C.
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Chung, H. L.
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Chou, W. C.
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Chen, W. K.
;
Chang, W. H.
This study explores the effects of both Oxygen and temperature on the carrier dynamics of isoelectronic ZnSe(1-x)O(x) (x=0.027 and 0.053) semiconductors using photoluminescence (PL) and time-resolved PL spectroscopy. We find that the Kohlrausch law is highly consistent with the complex decay traces induced by isoelectronic O traps, and the mechanism of carrier recombination undergoes a complicated change from trapped to free excitons with the increase in temperature. Complex recombination processes are clarified using the relaxation model based on various decay channels. These findings are consistent with the initial fall in the stretching exponent beta followed by its monotonic increase with increasing temperature. (C) 2010 American Institute of Physics. [doi:10.1063/1.3473776]
The influences of surface treatment and gas annealing conditions on the inversion behaviors of the atomic-layer-deposition Al(2)O(3)/n-In(0.53)Ga(0.47)As metal-oxide-semiconductor capacitor
(2010-07-26)
Trinh, H. D.
;
Chang, E. Y.
;
Wu, P. W.
;
Wong, Y. Y.
;
Chang, C. T.
The inversion behaviors of atomic-layer-deposition Al(2)O(3)/n-In(0.53)Ga(0.47)As metal-oxide-semiconductor capacitors are studied by various surface treatments and postdeposition annealing using different gases. By using the combination of wet sulfide and dry trimethyl aluminum surface treatment along with pure hydrogen annealing, a strong inversion capacitance-voltage (C-V) response is observed, indicating a remarkable reduction in interface trap state density (D(it)) at lower half-part of In(0.53)Ga(0.47)As band gap. This low D(it) was confirmed by the temperature independent C-V stretch-out and horizontal C-V curves. The x-ray photoelectron spectroscopy spectra further confirm the effectiveness of hydrogen annealing on the reduction of native oxides. (C) 2010 American Institute of Physics. [doi:10.1063/1.3467813]
Carrier dynamics in isoelectronic ZnSe1-xOx semiconductors
(2010-07-26)
Lin, Y. C.
;
Chung, H. L.
;
Chou, W. C.
;
Chen, W. K.
;
Chang, W. H.
This study explores the effects of both Oxygen and temperature on the carrier dynamics of isoelectronic ZnSe1-xOx (x=0.027 and 0.053) semiconductors using photoluminescence (PL) and time-resolved PL spectroscopy. We find that the Kohlrausch law is highly consistent with the complex decay traces induced by isoelectronic O traps, and the mechanism of carrier recombination undergoes a complicated change from trapped to free excitons with the increase in temperature. Complex recombination processes are clarified using the relaxation model based on various decay channels. These findings are consistent with the initial fall in the stretching exponent beta followed by its monotonic increase with increasing temperature. (C) 2010 American Institute of Physics. [doi:10.1063/1.3473776]
Power-rail ESD protection circuit without lock-on failure
(2010-07-27)
Ker
;
Ming-Dou
;
Yen
;
Cheng-Cheng
;
Chen
An ESD protection circuit including a discharge device, a first detection circuit, and a second detection circuit. The discharge device provides a discharge path between a first power rail and a second power rail when the discharge device is activated. The discharge device stops providing the discharge path when the discharge device is de-activated. The first detection circuit is coupled between the first and the second power rails. The first detection circuit activates the discharge device when an ESD event occurs in the first power rail. The second detection circuit de-activates the discharge device when the ESD event does not occur in the first power rail.
High-speed and localized resistive switching characteristics of double-layer SrZrO(3) memory devices
(2010-07-28)
Lin, Meng-Han
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Wu, Ming-Chi
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Huang, Chun-Yang
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Lin, Chen-Hsi
;
Tseng, Tseung-Yuen
The fabrication of SrZrO(3) (SZO) memory devices with oxygen-rich (OR) and oxygen-deficient (OD) double layers, their resistive switching (RS) characteristics and mechanisms are investigated in this study. Due to the difference in oxygen content between the OR and OD layers formed by an oxygen flow control (OFC) process during SZO deposition, the RS region is effectively reduced and localized within the OR layer, which leads to a low operation voltage and stable RS behaviours. Furthermore, the OFC SZO device exhibits high-speed switching (10 ns) over 400 times and long retention (>10(6) s), showing promising potential for next-generation nonvolatile memory applications.
High-speed and localized resistive switching characteristics of double-layer SrZrO3 memory devices
(2010-07-28)
Lin, Meng-Han
;
Wu, Ming-Chi
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Huang, Chun-Yang
;
Lin, Chen-Hsi
;
Tseng, Tseung-Yuen
The fabrication of SrZrO3 (SZO) memory devices with oxygen-rich (OR) and oxygen-deficient (OD) double layers, their resistive switching (RS) characteristics and mechanisms are investigated in this study. Due to the difference in oxygen content between the OR and OD layers formed by an oxygen flow control (OFC) process during SZO deposition, the RS region is effectively reduced and localized within the OR layer, which leads to a low operation voltage and stable RS behaviours. Furthermore, the OFC SZO device exhibits high-speed switching (10 ns) over 400 times and long retention (>10(6) s), showing promising potential for next-generation nonvolatile memory applications.
PLANAR ANTENNA
(2010-07-29)
Chung, Shyh-Jong
;
Wang, Sy-Been
;
Ling, Ching-Wei
The present invention discloses a planar antenna including a substrate, a ground plane and a feed line. The ground plane is disposed on one side of the substrate. The ground plane includes a hollow portion. The feed line disposed on another side of the substrate and corresponding to the hollow portion for feeding a signal. The present invention also discloses a planar antenna including a substrate, a ground plane and a feed line. The ground plane is disposed on one side of the substrate. The ground plane includes a first hollow portion and a second hollow portion. The feed line is disposed on another side of the substrate and having a first branch feed portion and a second branch feed portion for feeding a signal, and the first branch feed portion and the second branch feed portion are aligned with the first hollow portion and the second hollow portion respectively.
Parallel-RC Feedback Low-Noise Amplifier for UWB Applications
(2010-08-01)
He, Kuang-Chi
;
Li, Ming-Tsung
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Li, Chen-Ming
;
Tarng, Jenn-Hwan
;
電信工程研究所
A two-stage 3.1- to 10.6-GHz ultrawideband CMOS low-noise amplifier (LNA) is presented. In our design, a parallel resistance-capacitance shunt feedback with a source inductance is proposed to obtain broadband input matching and to reduce the noise level effectively; furthermore, a parallel inductance-capacitance network at drain is drawn to further suppress the noise, and a very low noise level is achieved. The proposed LNA is implemented by the Taiwan Semiconductor Manufacturing Company 0.18-mu m CMOS technology. Measured results show that the noise figure is 2.5-4.7 dB from 3.1 to 10.6 GHz, which may be the best result among previous reports in the 0.18-mu m CMOS 3.1- to 10.6-GHz ultrawideband LNA. The power gain is 10.9-13.9 dB from 3.1 to 10.6 GHz. The input return loss is below -9.4 dB from 3.1 to 15 GHz. It consumes 14.4 mW from a 1.4-V supply voltage and occupies an area of only 0.46 mm(2).
Prediction of small non-coding RNA in bacterial genomes using support vector machines
(2010-08-01)
Chang, Tzu-Hao
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Wu, Li-Ching
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Lin, Jun-Hong
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Huang, Hsien-Da
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Liu, Baw-Jhiune
Small non-coding RNA genes have been shown to play important regulatory roles in a variety of cellular processes, but prediction of non-coding RNA genes is a great challenge, using either an experimental or a computational approach, due to the characteristics of sRNAs, which are that sRNAs are small in size, are not translated into proteins and show variable stability. Most known sRNAs have been identified in Escherichia coli and have been shown to be conserved in closely related organisms. We have developed an integrative approach that searches highly conserved intergenic regions among related bacterial genomes for combinations of characteristics that have been extracted from known E. coli sRNA genes. Support vector machines (SVM) were then used with these characteristics to predict novel sRNA genes. (c) 2010 Elsevier Ltd. All rights reserved.
The flipping puzzle on a graph
(2010-08-01)
Huang, Hau-wen
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Weng, Chih-wen
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應用數學系
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Department of Applied Mathematics
Let S be a connected graph which contains an induced path of n - 1 vertices, where n is the order of S. We consider a puzzle on S. A configuration of the puzzle is simply an n-dimensional column vector over {0, 1} with coordinates of the vector indexed by the vertex set S. For each configuration u with a coordinate u(s) = 1, there exists a move that sends u to the new configuration which flips the entries of the coordinates adjacent to s in u. We completely determine if one configuration can move to another in a sequence of finite steps. (C) 2010 Published by Elsevier Ltd
Particular Failure Mechanism of GaN-Based Alternating Current Light-Emitting Diode Induced by GaOx Oxidation
(2010-08-01)
Yen, Hsi-Hsuan
;
Kuo, Hao-Chung
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Yeh, Wen-Yung
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光電工程學系
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光電工程研究所
This investigation describes the unique failure mechanism of the Wheatstone bridge circuit-type alternating current light-emitting diode (WB AC-LED). The micro-LEDs in WB AC-LED rectifying branches were reverse biased, and therefore, positive charges (holes) accumulated in the n-type GaN layer under the active region and combined with the GaN material and OH- ions to generate GaOx oxidation grains. The GaOx generation speed was fast with high reverse voltage applied to micro-LEDs, and the expansion of GaOx dimensions degraded the opto-electrical characteristics and eventually caused failure of the WB AC-LED. The root-mean-square reverse voltage dropped across each micro-LED from -13.1 to -6.7 V with different micro-LEDs array arrangements extended the WB AC-LED life-time from being less than 650 h to more than 1600 h, respectively.
Ultrasensitive semiconductor biochip for cancer marker detection
(2010-08-01)
Ko, Fu-Hsiang
;
Chuang, Cheng-Keng
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Pang, See-Tong
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Pan, Tung-Ming
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材料科學與工程學系
An interactive optimization system for the location of supplementary recycling depots
(2010-08-01)
Lin, Hung-Yueh
;
Chen, Guan-Hwa
;
Lee, Pei-Hao
;
Lin, Chun-Hsu
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環境工程研究所
In order to increase participation in residential recycling, convenient access to recycling depots is essential. Currently, most vendors have established various take-back systems in local retail shops. The integration of the recycling depots established by local authorities with these private facilities can significantly improve access for residents. As a response to this need, an integrated system capable of providing optimization analysis and geographical information system functions has been designed to assist local authorities in identifying the regions where supplementary recycling depots need to be located to improve access to. A customized program which allows online optimization analysis has been developed and embedded in an integrated system. Through a user-friendly interface, users can interactively locate the supplementary depots within the desired regions. The interactive process improves the flexibility of the integrated system and avoids the shortcomings of impractical locations for recycling depots. A case study of battery recycling in central Taiwan is presented to demonstrate the effectiveness of the integrated system. By using the proposed integrated system to analyze the existing conditions, the locations of supplementary points to improve access to the existing regional recycling collection points can be determined. In short, the proposed methodology provides local authorities with an uncomplicated and streamlined system with which to determine the number and locations of supplementary recycling points. (C) 2009 Elsevier B.V. All rights reserved.
Molecular hosts for triplet emitters in organic light-emitting diodes and the corresponding working principle
(2010-08-01)
Mi BaoXiu
;
Gao ZhiQiang
;
Liao ZhangJin
;
Huang Wei
;
Chen, Chin Hsin
This paper summarizes the mechanism and routes for excitation of triplet emitters in dopant emission based phosphorescent organic light-emitting diodes (PhOLEDs), providing a comprehensive overview of recent progress in molecular hosts for triplet emitters in PhOLEDs. Particularly, based on the nature of different hosts, e.g., hole transporting, electron transporting or bipolar materials, in which the dopant emitters can be hosted to generate phosphorescence, the respective device performances are summarized and compared. Highlights are given to the relationships among the molecular structure, thermal stability, triplet energy, carrier mobility, molecular orbital energy level and their corresponding device performances.
Diamond plates on dome-like particles: preparation, characterization and field emission properties
(2010-08-01)
Tiwari, Rajanish N.
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Chen, Wei-Chun
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Tiwari, Jitendra N.
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Wang, Wei-Lin
;
Chang, Li
Thin diamond microplates have been grown on dome-like/hemispherical carbon particles on titanium carbide by a microwave plasma chemical vapour deposition (MPCVD) method using a gas mixture of methane and hydrogen. The diamond microplates have a thickness of about 200 nm. A thin (300 nm) film of titanium carbide was formed during carburization of sputtered titanium on an Si(100) substrate in MPCVD. The hemispherical carbon particles were covered with diamond microplates. The diamond microplates are isolated electron-emitting spherules and exhibit a low threshold (50 V mu m (1)) and high current density (0.92 mA cm(-2)) in their field emission properties. A possible mechanism for the formation of the diamond microplates and hemispherical carbon particles is presented.