Browsing by Issue Date, starting with "2011-07-25"

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Loycal atomic and electronic structures and ferroelectric properties of PbZr(0.52)Ti(0.48)O(3): An x-ray absorption study
(2011-07-25)
Ray, S. C.
;
Hsueh, H. C.
;
Wu, C. H.
;
Pao, C. W.
;
Asokan, K.
This work investigates local atomic and electronic structures of PbZr(0.52)Ti(0.48)O(3) (PZT) thin films with < 001 >, < 101 >, and < 111 > orientations using extended x-ray absorption fine structure (EXAFS) and x-ray absorption near-edge structure (XANES) spectroscopy with theta = 0 degrees and 70 degrees incident angles. The EXAFS result indicates that the < 001 >-oriented PZT film has a polarization dominantly along the c-axis, while both < 101 >- and < 111 >-oriented PZT films have a dominant in-ab-plane polarization. The hysteresis-loop measurements show that the < 001 >-oriented PZT film has a much larger coercive field than those of other two PZT films, which indicates that the double-well potential along the c-axis is much deeper than that in the ab-plane. (C) 2011 American Institute of Physics. [doi:10.1063/1.3607475]
Loycal atomic and electronic structures and ferroelectric properties of PbZr0.52Ti0.48O3: An x-ray absorption study
(2011-07-25)
Ray, S. C.
;
Hsueh, H. C.
;
Wu, C. H.
;
Pao, C. W.
;
Asokan, K.
This work investigates local atomic and electronic structures of PbZr0.52Ti0.48O3 (PZT) thin films with < 001 >, < 101 >, and < 111 > orientations using extended x-ray absorption fine structure (EXAFS) and x-ray absorption near-edge structure (XANES) spectroscopy with theta = 0 degrees and 70 degrees incident angles. The EXAFS result indicates that the < 001 >-oriented PZT film has a polarization dominantly along the c-axis, while both < 101 >- and < 111 >-oriented PZT films have a dominant in-ab-plane polarization. The hysteresis-loop measurements show that the < 001 >-oriented PZT film has a much larger coercive field than those of other two PZT films, which indicates that the double-well potential along the c-axis is much deeper than that in the ab-plane. (C) 2011 American Institute of Physics. [doi:10.1063/1.3607475]
High Q microcavity light emitting diodes with buried AlN current apertures
(2011-07-25)
Cheng, Bo-Siao
;
Wu, Yun-Lin
;
Lu, Tien-Chang
;
Chiu, Ching-Hsueh
;
Chen, Cheng-Hung
We demonstrate a GaN-based high-Q microcavity light emitting diode (MCLED) with a buried AlN current aperture. A thin AlN layer is inserted on the InGaN/GaN multiple quantum wells as a current blocking layer and an optical confinement layer. The GaN-based MCLED is composed of a 29-pair GaN/AlN distributed Bragg reflector (DBR), an eight-pair of SiO(2)/Ta(2)O(5) dielectric DBR, and a three-lambda optical thickness InGaN/GaN active region. The current can be injected more effectively in the MCLED with a buried AlN current aperture. The output emission has a dominant emission peak wavelength at 440 nm with a very narrow linewidth of 0.52 nm, corresponding to a cavity Q-value of 846 at a driving current of 5 mA. (C) 2011 American Institute of Physics. [doi:10.1063/1.3617418]
Robust bi-stable memory operation in single-layer graphene ferroelectric memory
(2011-07-25)
Song, Emil B.
;
Lian, Bob
;
Kim, Sung Min
;
Lee, Sejoon
;
Chung, Tien-Kan
With the motivation of realizing an all graphene-based circuit for low power, we present a reliable nonvolatile graphene memory device, single-layer graphene (SLG) ferroelectric field-effect transistor (FFET). We demonstrate that exfoliated single-layer graphene can be optically visible on a ferroelectric lead-zirconate-titanate (PZT) substrate and observe a large memory window that is nearly equivalent to the hysteresis of the PZT at low operating voltages in a graphene FFET. In comparison to exfoliated graphene, FFETs fabricated with chemical vapor deposited (CVD) graphene exhibit enhanced stability through a bi-stable current state operation with long retention time. In addition, we suggest that the trapping/de-trapping of charge carriers in the interface states is responsible for the anti-hysteresis behavior in graphene FFET on PZT. (C) 2011 American Institute of Physics. [doi:10.1063/1.3619816]
miRTar: an integrated system for identifying miRNA-target interactions in human
(2011-07-26)
Hsu, Justin Bo-Kai
;
Chiu, Chih-Min
;
Hsu, Sheng-Da
;
Huang, Wei-Yun
;
Chien, Chia-Hung
Background: MicroRNAs (miRNAs) are small non-coding RNA molecules that are similar to 22-nt-long sequences capable of suppressing protein synthesis. Previous research has suggested that miRNAs regulate 30% or more of the human protein-coding genes. The aim of this work is to consider various analyzing scenarios in the identification of miRNA-target interactions, as well as to provide an integrated system that will aid in facilitating investigation on the influence of miRNA targets by alternative splicing and the biological function of miRNAs in biological pathways. Results: This work presents an integrated system, miRTar, which adopts various analyzing scenarios to identify putative miRNA target sites of the gene transcripts and elucidates the biological functions of miRNAs toward their targets in biological pathways. The system has three major features. First, the prediction system is able to consider various analyzing scenarios (1 miRNA: 1 gene, 1: N, N: 1, N: M, all miRNAs: N genes, and N miRNAs: genes involved in a pathway) to easily identify the regulatory relationships between interesting miRNAs and their targets, in 3'UTR, 5'UTR and coding regions. Second, miRTar can analyze and highlight a group of miRNA-regulated genes that participate in particular KEGG pathways to elucidate the biological roles of miRNAs in biological pathways. Third, miRTar can provide further information for elucidating the miRNA regulation, i.e., miRNA-target interactions, affected by alternative splicing. Conclusions: In this work, we developed an integrated resource, miRTar, to enable biologists to easily identify the biological functions and regulatory relationships between a group of known/putative miRNAs and protein coding genes. miRTar is now available at http://miRTar.mbc.nctu.edu.tw/.
Nanoscale Structure and Mechanism for Enhanced Electromechanical Response of Highly Strained BiFeO(3) Thin Films
(2011-07-26)
Damodaran, Anoop R.
;
Liang, Chen-Wei
;
He, Qing
;
Peng, Chun-Yen
;
Chang, Li
The presence of a variety of structural variants in BiFeO(3) thin films give rise to exotic electric-field-induced responses and resulting electromechanical responses as large as 5%. Using high-resolution X-ray diffraction and scanning-probe-microscopy-based studies the numerous phases present at the phase boundaries are identified and an intermediate monoclinic phase, in addition to the previously observed rhombohedral- and tetragonal-like phases, is discovered.
Nanoscale Structure and Mechanism for Enhanced Electromechanical Response of Highly Strained BiFeO3 Thin Films
(2011-07-26)
Damodaran, Anoop R.
;
Liang, Chen-Wei
;
He, Qing
;
Peng, Chun-Yen
;
Chang, Li
The presence of a variety of structural variants in BiFeO3 thin films give rise to exotic electric-field-induced responses and resulting electromechanical responses as large as 5%. Using high-resolution X-ray diffraction and scanning-probe-microscopy-based studies the numerous phases present at the phase boundaries are identified and an intermediate monoclinic phase, in addition to the previously observed rhombohedral- and tetragonal-like phases, is discovered.
Method for carry estimation of reduced-width multipliers
(2011-07-28)
Liao Yen-Chin
;
Chang Hsie-Chia
A low-error reduced-width multiplier is provided by the present invention. The multiplier can dynamically compensate the truncation error. The compensation value is derived by the dependencies among the multiplier partial products, and thus, can be analyzed according to the multiplication type and the multiplier input statistics.
Observation of Inverted Regime Electron Transfer in CdSe/ZnS QDs from pH-Sensitive Single-Particle and Ensemble Fluorescence Measurements
(2011-07-28)
Ko, H. C.
;
Yuan, C. T.
;
Lin, S. H.
;
Tang, Jau
;
應用化學系
In this report, we investigated the pH dependence of the photoluminescence of CdSe/ZnS quantum dots (QDs). We present experimental results and theoretical analysis of both the blinking behavior of single-QDs as well as the fluorescence intensity time trace from an ensemble of QDs in agarose gel fibers at different pH environments. Such a combined approach of confined QDs by single-particle and ensemble measurements has not been used previously. This study allows us to elucidate the electron transfer processes from the light state to the dark state. The observed increase in both the activation energy for the charge transfer and the free energy gap between the light and the dark states at an increased concentration of H(+) ions supported the Marcus inverted-regime, electron transfer.
GRAY LEVEL WEIGHTING CENTROID METHOD FOR HOLOGRAPHIC DATA STORAGE
(2011-07-28)
OU-YANG MANG
;
CHEN YU-TA
A gray level weighting centroid method for holographic data storage is disclosed. Firstly, a first gray level image having a plurality of blocks is received. Then, a convolution calculation is performed on a weight matrix and the image, so as to obtain a second gray level image having a plurality of blocks each having a gray level value. The gray level values are divided into a bright gray level value and a dark gray level value by a threshold value, so as to convert the second gray level image into a thresholding image and find the positions of the borders of the blocks corresponding to the bright gray level value. Next, the blocks surrounded by the positions of the borders and respectively used as a centroid block are found by making the positions of the borders correspond to the first gray level image. Finally, the centroid block is calculated to obtain a centroid point.
Dislocation reduction in GaN film using Ga-lean GaN buffer layer and migration enhanced epitaxy
(2011-07-29)
Wong, Yuen-Yee
;
Chang, Edward Yi
;
Wu, Yue-Han
;
Hudait, Mantu K.
;
Yang, Tsung-Hsi
A GaN buffer layer grown under Ga-lean conditions by plasma-assisted molecular beam epitaxy (PAMBE) was used to reduce the dislocation density in a GaN film grown on a sapphire substrate. The Ga-lean buffer, with inclined trench walls on its surface, provided an effective way to bend the propagation direction of dislocations, and it reduced the dislocation density through recombination and annihilation processes. As a result, the edge dislocation density in the GaN film was reduced by approximately two orders of magnitude to 2 x 10(8) cm(-2). The rough surface of the Ga-lean buffer was recovered using migration enhanced epitaxy (MEE), a process of alternating deposition cycle of Ga atoms and N(2) radicals, during the PAMBE growth. By combining these two methods, a GaN film with high-crystalline-quality and atomically-flat surface can be achieved by PAMBE on a lattice mismatch substrate. (C) 2011 Elsevier B.V. All rights reserved.
An improved genetic programming to SSM/I estimation typhoon precipitation over ocean
(2011-07-30)
Chen, Li
;
Yeh, Keh-Chia
;
Wei, Hsiao-Ping
;
Liu, Gin-Rong
;
土木工程學系
This article proposes an improved multi-run genetic programming (GP) and applies it to estimate the typhoon rainfall over ocean using multi-variable meteorological satellite data. GP is a well-known evolutionary programming and data mining method used to automatically discover the complex relationships among nonlinear systems. The main advantage of GP is to optimize appropriate types of function and their associated coefficients simultaneously. However, the searching efficiency of traditional GP can be decreased by the complex structure of parse tree to represent the multiple input variables. This study processed an improvement to enhance escape ability from local optimums during the optimization procedure. We continuously run GP several times by replacing the terminal nodes at the next run with the best solution at the current run. The current method improves GP, obtaining a highly nonlinear meaningful equation to estimate the rainfall. In the case study, this improved GP (IGP) described above combined with special sensor microwave imager (SSM/I) seven channels was employed. These results are then verified with the data from four offshore rainfall stations located on islands around Taiwan. The results show that the IGP generates sophisticated and accurate multi-variable equation through two runs. The performance of IGP outperforms the traditional multiple linear regression, back-propagated network (BPN) and three empirical equations. Because the extremely high values of precipitation rate are quite few and the number of zero values (no rain) is very large, the underestimations of heavy rainfall are obvious. A simple genetic algorithm was therefore used to search for the optimal threshold value of SSM/I channels, detecting the data of no rain. The IGP with two runs, used to construct an appropriate mathematical function to estimate the precipitation, can obtain more favourable results from estimating extremely high values. Copyright. (C) 2011 John Wiley & Sons, Ltd.
Antibodies against Helicobacter pylori heat shock protein 60 aggravate HSP60-mediated proinflammatory responses
(2011-08-01)
Liao, Kuang-Wen
;
Lin, Chen-Si
;
Chen, Wen-Liang
;
Yang, Chu-Ting
;
Lin, Ching-Min
Anti-Helicobacter pylori heat shock protein 60 (HpHSP60) antibodies are Usually found in H. pylori-infected patients and are known to be associated with the progression of gastric diseases. However, the effects of these antibodies on the functions of HpHSP60 have not been identified. This study aims to investigate the effects of the interaction between anti-HSP60 antibodies and HpHSP60 on inflammatory responses. Anti-HpHSP60 polyclonal sera and monoclonal antibodies (mAbs) were produced to evaluate their effects on HpHSP60-induced IL-8 and TNF-alpha activity. The results indicated that anti-HpHSP60 polyclonal sera collected from patients infected with H. pylori or from rabbit and mice immunized with HpHSP60 could significantly enhance HpHSP60-mediated IL-8 and TNF-alpha secretion from monocytic THP-1 cells. Similar effects were also found with anti-HpHSP60 mAbs. Further analysis revealed that this phenomenon was only carried out by anti-HpHSP60 antibody but not by other non-specific mAbs. Moreover, the non-specific mAbs decreased the synergism of HpHSP60 and anti-HpHSP60 mAbs in proinflammatory cytokine induction. Herein, we have examined the role of anti-HpHSP60 antibody in host immune responses for the first time. This study demonstrated that H. pylori HSP60/mAbs could modulate helico-bacterial pathogenesis by increasing IL-8 and TNF-alpha production. The pathogen-specific antibodies may execute potential immune functions rather than recognize or neutralize microbes. (C) 2011 Elsevier Ltd. All rights reserved.
Accessing Manufacturing Yield for Gamma Wafer Sawing Processes in COG Packaging
(2011-08-01)
Pearn, Wen-Lea
;
Tai, Yu-Ting
;
Huang, Kai-Bin
;
Ku, Pin-Lun
;
工業工程與管理學系
The technology of thin film transistor liquid crystal display (LCD) has become more popular due to great demand for worldwide consumer electronic products. Driver integrated circuit (IC) is a critical device that is embedded sophisticated circuits to drive panels. Since narrow border design on display products is current trend, dimensions of driver ICs are shrunken. In the high-density LCD driver ICs, the operation of wafer sawing is essential and needs accurate yield assessment. However, inevitable process variance changes could arise from sawing machine, material, operation, and workmanship, and may not be detected within short time. Conventionally, manufacturing yield is evaluated applying typical yield measure index method under the assumptions that the processes are stable and normal. To assess manufacturing yield for Gamma wafer sawing processes more accurately, we present a modified yield measure index method. Using the proposed method, the magnitudes of the undetected variance change, which are functions of the detection power of the S(2) chart, are incorporated into the evaluation of manufacturing yield. In addition, we demonstrate, mathematically, that the accommodation would not be affected by the scale parameter of Gamma distribution. For illustration purpose, a real-world case in a wafer sawing factory which is located on the Science-based Industrial Park in Hsinchu, Taiwan, is presented.
鎖相迴路頻率合成器及其迴路鎖定方法
(2011-08-01)
陳巍仁
;
李彥緯
一種鎖相迴路頻率合成器及其迴路鎖定方法，該鎖相迴路頻率合成器包括參考路徑和差調變器回授電路、耦接於該參考路徑和差調變器回授電路的輸出端之參考相位積分電路、耦接於該參考相位積分電路的輸出端之相位/頻率偵測器、耦接於該相位/頻率偵測器的輸出端及該參考路徑和差調變器回授電路的輸入端之迴路濾波器、耦接於該迴路濾波器輸出端之振盪器、以及耦接於該振盪器的輸出端及該相位/頻率偵測器的輸入端之回授相位積分電路。藉由本發明鎖相迴路頻率合成器，使振盪器能產生對應參考訊號之頻率訊號，並具有抗雜訊、提高解析度及易於整合之功效。
Low-Power and Highly Reliable Multilevel Operation in ZrO(2) 1T1R RRAM
(2011-08-01)
Wu, Ming-Chi
;
Lin, Yi-Wei
;
Jang, Wen-Yueh
;
Lin, Chen-Hsi
;
Tseng, Tseung-Yuen
The Ti/ZrO(2)/Pt resistive memory devices with one transistor and one resistor (1T1R) architecture are successfully fabricated in this letter. The tested devices show low operation current (20 mu A), low switching voltage (set/reset, 0.8/-1 V), and reliable data retention for low-resistance state (LRS) with a 20-mu A set current at 80 degrees C (over ten years) via an excellent current limiter, namely, a metal-oxide-semiconductor field-effect transistor (MOSFET). In addition, multilevel storage characteristics are also demonstrated by modulating the amplitude of the MOSFET gate voltage. The various LRS levels obtained are possibly attributed to the formation of different numbers and sizes of conducting filaments consisting of oxygen vacancies caused by an external electric field. Moreover, reproducible resistive switching characteristics up to 2000 switching cycles are achieved in the same device. Our 1T1R ZrO(2)-based resistive switching access memory with low-power and highly reliable multilevel operation has high potential for practical applications.
Polyimide/Ta(2)O(5) nanocomposite gate insulators for enhanced organic thin-film transistor performance
(2011-08-01)
Chen, Liang-Hsiang
;
Lin, Pang
;
Ho, Jia-Chong
;
Lee, Cheng-Chung
;
Kim, Choongik
This study reports the preparation and characterization of polyimide/Ta(2)O(5) nanocomposite films as insulators for organic thin-film transistors (OTFTs). The degree of imidization, thermal, electrical, and surface properties of the nanocomposite films were characterized as a function of Ta(2)O(5) precursor contents. The nanocomposite films, with controlled/comparable insulator electrical characteristics and surface properties, have been found to enhance dielectric constant compared to pristine polyimide films, which resulted in improved pentacene TFT performance by a factor of 2-3 with carrier mobility values as high as 0.38 cm(2)/Vs. (C) 2011 Elsevier B.V. All rights reserved.
Highly reliable Si3N4-HfO2 stacked heterostructure to fully flexible poly-(3-hexylthiophene) thin-film transistor
(2011-08-01)
Meena, Jagan Singh
;
Chu, Min-Ching
;
Wu, Chung-Shu
;
Chang, Feng-Chih
;
Ko, Fu-Hsiang
A new and fully flexible Si3N4-HfO2 stacked poly-(3-hexylthiophene) p-type thin film transistor (P3HT-TFT) was successfully fabricated on thin semi-transparent polyimide (PI) substrate. The success of the TFT manufacturing adopts: (a) very simple and cost-effective sol-gel spin-coating technique to obtain 10-nm high-k HfO2 as dielectric layer over fully flexible PI substrate; (b) 50-nm silicon nitride (Si3N4) as the most efficient passivation layer on top of HfO2 film; (c) bendable 30-nm P3HT channel film by spin-coating method. Current-electric field characteristics of HfO2 layer in metal-insulator-metal (MIM) and TFT configurations, with or without Si3N4 passivation layer, were carefully evaluated. The origin of unsatisfactory leakage current in MIM and TFT structures could be effectively suppressed by means of Si3N4 film as the efficient passivation layer. The bottom-gate TFT demonstrated the on-to-off ratio 2 x 10(4) for drain current, -1.9 V threshold voltage and good saturation mobility (0.041 cm(2) V (1) s (1)). The proposed devices were examined in convex and concave types of various radii of curvature (R-C) in order to explore the manufacturing feasibility and electrical reliability of the fully flexible TFT for practical applications. In addition, various folding times and environmental stability on aforementioned devices with respective to electrical performances were also evaluated. (C) 2011 Elsevier B.V. All rights reserved.
Low-Power and Highly Reliable Multilevel Operation in ZrO2 1T1R RRAM
(2011-08-01)
Wu, Ming-Chi
;
Lin, Yi-Wei
;
Jang, Wen-Yueh
;
Lin, Chen-Hsi
;
Tseng, Tseung-Yuen
The Ti/ZrO2/Pt resistive memory devices with one transistor and one resistor (1T1R) architecture are successfully fabricated in this letter. The tested devices show low operation current (20 mu A), low switching voltage (set/reset, 0.8/-1 V), and reliable data retention for low-resistance state (LRS) with a 20-mu A set current at 80 degrees C (over ten years) via an excellent current limiter, namely, a metal-oxide-semiconductor field-effect transistor (MOSFET). In addition, multilevel storage characteristics are also demonstrated by modulating the amplitude of the MOSFET gate voltage. The various LRS levels obtained are possibly attributed to the formation of different numbers and sizes of conducting filaments consisting of oxygen vacancies caused by an external electric field. Moreover, reproducible resistive switching characteristics up to 2000 switching cycles are achieved in the same device. Our 1T1R ZrO2-based resistive switching access memory with low-power and highly reliable multilevel operation has high potential for practical applications.
Modeling the CO(2) emissions, energy use, and economic growth in Russia
(2011-08-01)
Pao, Hsiao-Tien
;
Yu, Hsiao-Cheng
;
Yang, Yeou-Herng
;
管理科學系
;
科技管理研究所
This paper applies the co-integration technique and causality test to examine the dynamic relationships between pollutant emissions, energy use, and real output during the period between 1990 and 2007 for Russia. The empirical results show that in the long-run equilibrium, emissions appear to be energy use elastic and output inelastic. This elasticity suggests high energy use responsiveness to changes in emissions. The output exhibits a negative significant impact on emissions and does not support EKC hypothesis. These indicate that both economic growth and energy conservation policies can reduce emissions and no negative impact on economic development The causality results indicate that there is a bidirectional strong Granger-causality running between output, energy use and emissions, and whenever a shock occurs in the system, each variable makes a short-run adjustment to restore the long-run equilibrium. The average speed of adjustment is as low as just over 0.26 years. Hence, in order to reduce emissions, the best environmental policy is to increase infrastructure investment to improve energy efficiency, and to step up energy conservation policies to reduce any unnecessary waste of energy. That is, energy conservation is expected to improve energy efficiency, thereby promoting economic growth. (C) 2011 Elsevier Ltd. All rights reserved.