Browsing by Issue Date, starting with "2013-07-22"

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Fabrication, characterization and simulation of Omega-gate twin poly-Si FinFET nonvolatile memory
(2013-07-22)
Yeh, Mu-Shih
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Wu, Yung-Chun
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Hung, Min-Feng
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Liu, Kuan-Cheng
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Jhan, Yi-Ruei
This study proposed the twin poly-Si fin field-effect transistor (FinFET) nonvolatile memory with a structure that is composed of Omega-gate nanowires (NWs). Experimental results show that the NW device has superior memory characteristics because its Omega-gate structure provides a large memory window and high program/erase efficiency. With respect to endurance and retention, the memory window can be maintained at 3.5 V after 10(4) program and erase cycles, and after 10 years, the charge is 47.7% of its initial value. This investigation explores its feasibility in the future active matrix liquid crystal display system-on-panel and three-dimensional stacked flash memory applications.
The investigation of donor-acceptor compatibility in bulk-heterojunction polymer systems
(2013-07-22)
Huang, Jen-Hsien
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Hsiao, Yu-Sheng
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Richard, Eric
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Chen, Chun-Chao
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Chen, Peilin
The fullerene derivative, indene-C-60 bisadduct (ICBA), has been introduced into poly(3-hexylthiophene) (P3HT) to improve the efficiency of P3HT-based devices. However, we found that ICBA is not suitable for most low bandgap polymers. In this study, we have correlated the cell performance with surface energy between the donor and acceptor materials in a bulk-heterojunction cell. These results show that higher photocurrent can be attributed to the morphology improvement induced by larger surface energy difference (Delta gamma) between the low bandgap polymer and fullerene. These results also suggest that synthetic strategies which adjust the Delta gamma between donor and acceptor should be considered. (C) 2013 AIP Publishing LLC.
交大e-News第145期
(2013-07-22)
Secretariat
;
國立交通大學秘書室
High-Performance Flexible Waveguiding Photovoltaics
(2013-07-22)
Chou, Chun-Hsien
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Chuang, Jui-Kang
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Chen, Fang-Chung
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光電學院
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光電工程學系
The use of flat-plane solar concentrators is an effective approach toward collecting sunlight economically and without sun trackers. The optical concentrators are, however, usually made of rigid glass or plastics having limited flexibility, potentially restricting their applicability. In this communication, we describe flexible waveguiding photovoltaics (FWPVs) that exhibit high optical efficiencies and great mechanical flexibility. We constructed these FWPVs by integrating poly-Si solar cells, a soft polydimethylsiloxane (PDMS) waveguide, and a TiO2-doped backside reflector. Optical microstructures that increase the light harvesting ability of the FWPVs can be fabricated readily, through soft lithography, on the top surface of the PDMS waveguide. Our optimized structure displayed an optical efficiency of greater than 42% and a certified power conversion efficiency (PCE) of 5.57%, with a projected PCE as high as approximately 18%. This approach might open new avenues for the harvesting of solar energy at low cost with efficient, mechanically flexible photovoltaics.
Enhancement of the stability of resistive switching characteristics by conduction path reconstruction
(2013-07-22)
Huang, Jheng-Jie
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Chang, Ting-Chang
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Yu, Chih-Cheng
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Huang, Hui-Chun
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Chen, Yu-Ting
In this study, a Pt/BiFeO3/TiN device was fabricated and the resistance switching characteristics were investigated. After the first forming process, the conduction path was formed and exhibited unstable bipolar switching characteristics. Subsequently, the original conduction path was destroyed thoroughly by high negative bias. By reconstructing the conduction path after a second forming process (re-forming process), the device exhibits stable bipolar switching characteristics. Transmission electron microscopy analysis indicates that the stability of switching behavior was enhanced because of the joule heating effect, and is an easy way to improve the resistance switching characteristics. (C) 2013 AIP Publishing LLC.
Lambda(b) -> pl(-)(v)over-bar(l) form factors from lattice QCD with static b quarks
(2013-07-23)
Detmold, William
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Lin, C-J. David
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Meinel, Stefan
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Wingate, Matthew
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物理研究所
We present a lattice QCD calculation of form factors for the decay Lambda(b) -> p mu(-)(v) over bar (mu), which is a promising channel for determining the Cabibbo- Kobayashi-Maskawa matrix element vertical bar V-ub vertical bar at the Large Hadron Collider. In this initial study we work in the limit of static b quarks, where the number of independent form factors reduces to two. We use dynamical domain-wall fermions for the light quarks, and perform the calculation at two different lattice spacings and at multiple values of the light-quark masses in a single large volume. Using our form factor results, we calculate the Lambda(b) -> p mu-(v) over bar (mu) differential decay rate in the range 14 GeV2 <= q(2) <= q(max)(2), and obtain the integral integral(q2max)(14 GeV2) [d Gamma/dq(2)]dq(2)/vertical bar V-ub vertical bar(2) = 15.3 +/- 4.2 ps(-1). Combined with future experimental data, this will give a novel determination of vertical bar V-ub vertical bar with about 15% theoretical uncertainty. The uncertainty is dominated by the use of the static approximation for the b quark, and can be reduced further by performing the lattice calculation with a more sophisticated heavy-quark action.
N-bit digital-to-analog converting device
(2013-07-23)
Tseng Wei-Hsin
;
Wu Jieh-Tsorng
An N-bit digital-to-analog converting device includes: a decoder for converting an N-bit binary digital signal into a multi-bit thermometer code during each cycle of a clock signal alternating between first and second states, N being an integer not less than two; a random number generator for generating a reset signal having at least one high logic level bit and at least one low logic level bit that are equal in number and that have a random, time-varying arrangement; and a converting module coupled electrically to the decoder and the random number generator, and configured to convert the thermometer code into an analog voltage corresponding to the digital signal when the clock signal is in the first state, and to reset the analog voltage to a reset value according to the reset signal when the clock signal is in the second state.
YjcC, a c-di-GMP Phosphodiesterase Protein, Regulates the Oxidative Stress Response and Virulence of Klebsiella pneumoniae CG43
(2013-07-23)
Huang, Ching-Jou
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Wang, Zhe-Chong
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Huang, Hsi-Yuan
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Huang, Hsien-Da
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Peng, Hwei-Ling
This study shows that the expression of yjcC, an in vivo expression (IVE) gene, and the stress response regulatory genes soxR, soxS, and rpoS are paraquat inducible in Klebsiella pneumoniae CG43. The deletion of rpoS or soxRS decreased yjcC expression, implying an RpoS- or SoxRS-dependent control. After paraquat or H2O2 treatment, the deletion of yjcC reduced bacterial survival. These effects could be complemented by introducing the DyjcC mutant with the YjcC-expression plasmid pJR1. The recombinant protein containing only the YjcC-EAL domain exhibited phosphodiesterase (PDE) activity; overexpression of yjcC has lower levels of cyclic di-GMP. The yjcC deletion mutant also exhibited increased reactive oxygen species (ROS) formation, oxidation damage, and oxidative stress scavenging activity. In addition, the yjcC deletion reduced capsular polysaccharide production in the bacteria, but increased the LD50 in mice, biofilm formation, and type 3 fimbriae major pilin MrkA production. Finally, a comparative transcriptome analysis showed 34 upregulated and 29 downregulated genes with the increased production of YjcC. The activated gene products include glutaredoxin I, thioredoxin, heat shock proteins, chaperone, and MrkHI, and proteins for energy metabolism (transporters, cell surface structure, and transcriptional regulation). In conclusion, the results of this study suggest that YjcC positively regulates the oxidative stress response and mouse virulence but negatively affects the biofilm formation and type 3 fimbriae expression by altering the c-di-GMP levels after receiving oxidative stress signaling inputs.
Controllable Disorder in a Hybrid Nanoelectronic System: Realization of a Superconducting Diode
(2013-07-24)
Lo, Shun-Tsung
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Chen, Kuang Yao
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Lin, Sheng-Di
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Wu, J-Y.
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Lin, T. L.
We have studied a hybrid nanoelectronic system which consists of an AlGaAs/GaAs two-dimensional electron gas (2DEG) in close proximity (similar to 70 nm) to an Al superconducting nanofilm. By tuning the current through the Al film, we can change the conductance of the 2DEG and furthermore vary the effective disorder in the Al superconducting film in a controllable way. When a high current is injected into the film, screening which couples the Al film and the 2DEG results in a collapse of anti-symmetric behavior in the current-voltage characteristics, V(I) similar to - V(-I), which holds true in a conventional superconductor. Our results may open a new avenue of experimentally realizing a superconducting diode.
Plastic response of dislocation glide in solid helium under dc strain-rate loading
(2013-07-24)
Zhou, Caizhi
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Su, Jung-Jung
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Graf, Matthias J.
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Reichhardt, Charles
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Balatsky, Alexander V.
We develop a model for the gliding of dislocations and plasticity in solid He-4. This model takes into account the Peierls barrier, multiplication and interaction of dislocations, as well as classical thermally and mechanically activated processes leading to dislocation glide. We specifically examine the dc stress-strain curve and how it is affected by temperature, strain rate, and dislocation density. As a function of temperature and shear strain, we observe plastic deformation and discuss how this may be related to the experimental observation of elastic anomalies in solid hcp He-4 that have been discussed in connection with the possibility of supersolidity or giant plasticity. Our theory gives several predictions for the dc stress strain curves, for example, the yield point and the change in the work-hardening rate and plastic dissipation peak, that can be compared directly to constant strain-rate experiments and thus provide bounds on model parameters.
BAND-NOTCHED ULTRA-WIDEBAND ANTENNA
(2013-07-25)
Chung Shyh-Jong
;
Chuang Chao-Tang
A band-notched ultra-wideband antenna comprises a top layer non-uniform short-circuit metal patch, a middle layer metal radiation patch, and a bottom layer metal patch. The bottom layer metal patch includes a coupled open/short circuit stub which is set close to the middle layer metal radiation patch. The equivalent circuit of the top layer non-uniform short-circuit metal patch is a parallel LC resonator, and the equivalent circuit of the coupled open/short circuit stub is a series LC resonator. The resonant frequency of the top layer non-uniform short-circuit metal patch is equivalent to the resonant frequency of the coupled open/short circuit stub, so as to function as a second-order bandstop filter to yield high notch-band-edge selectivity without increasing total circuit area of the band-notched ultra-wideband antenna.
INTELLIGENT ANALYSIS METHOD OF LEAKAGE CURRENT DATA FOR CHIP CLASSIFICATION
(2013-07-25)
WEN Charles Hung-Pin
;
CHANG Chia-Ling
An intelligent analysis method of leakage current data for chip classification is provided. The analysis method includes steps of: providing a plurality of given patterns to a chip and measuring a plurality of leakage currents of the chip corresponding to the given patterns; finding a minimum value of the leakage currents and deriving an uninfected process parameter according to the minimum value; calculating a plurality of σ-Iddq values based on the uninfected process parameter and the given patterns; and applying a clustering algorithm to the σ-Iddq values to classify whether the chip is a defect-free one. By employing the novel method, it is advantageous of high efficiency and precision without involving any threshold-value determination, visual inspection and/or pattern modification.
An endoscopic system adopting a liquid crystal lens with an electrically tunable depth-of-field
(2013-07-29)
Chen, Hung-Shan
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Lin, Yi-Hsin
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光電工程學系
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Department of Photonics
Conventional endoscopic systems consisting of several solid lenses suffer from a fixed and limited depth-of-field (DOF). For practical applications, conventional endoscopes mechanically change the distance between the solid lenses of a lens module in order to change the focusing plane and DOF to see clearly in a scene. In this paper, we demonstrate an electrically tunable endoscopic system adopting a liquid crystal lens. By means of tunable focusing properties of the LC lens as a positive lens and a negative lens, the object at different objective distances can be imaged to the image sensor clearly and the corresponding depth-of-field can also help to enlarge the total spatial depth perception in a scene. The optical mechanism is discussed. In the experiments, under adjustment of three discrete lens powers of the LC lens, the viewing range or total spatial depth perception of the endoscopic system is from 76.4 mm to 12.4 mm which is 2x improved compared to the conventional one without LC lens. We believe this study can be extended to the applications of industrial and medical endoscopes. (C) 2013 Optical Society of America
Effects of crystallization mechanism on the electrical characteristics of green continuous-wave-laser-crystallized polycrystalline silicon thin film transistors
(2013-07-29)
Chou, Chia-Hsin
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Lee, I-Che
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Yang, Po-Yu
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Hu, Ming-Jhe
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Wang, Chao-Lung
Thin film transistors (TFTs) with amorphous silicon films crystallized via continuous-wave green laser at a wavelength of 532 nm exhibit very different electrical characteristics in various crystallization regions, corresponding to the Gaussian energy density distribution of the laser beam. In the center region subjected to the highest energy density, the full melting scheme led to the best crystallinity of the polycrystalline silicon film, resulting in the highest field-effect mobility of 500 cm(2) V-1 s(-1). In contrast, the edge region that resulted in solid phase crystallization exhibited the worst mobility of 48 cm 2 V-1 s(-1) for the polycrystalline silicon TFTs. (C) 2013 AIP Publishing LLC.
Effects of ZnO-nanostructure antireflection coatings on sulfurization-free Cu2ZnSnS4 absorber deposited by single-step co-sputtering process
(2013-07-29)
Jheng, Bao-Tang
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Liu, Po-Tsun
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Wang, Min-Chuan
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Wu, Meng-Chyi
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電子工程學系及電子研究所
ZnO nanostructures as anti-reflective coatings were synthesized by using hydrothermal technique for a sulfurization-free Cu2ZnSnS4 absorber prepared by co-sputtering deposition. By controlling the morphology of solution-grown ZnO nanostructures, the average reflectance of the Cu2ZnSnS4 solar cell with branched ZnO nanorods decreased from 7.6% to 1.12%, and the energy conversion efficiency promoted by 10.4% from the initial value of 4.8% to 5.3%. The efficiency improvement was well studied with the effects of the gradually increased refractive index between the air and the top electrode of Cu2ZnSnS4 solar device, due to the presence of the ZnO nanostructure. (C) 2013 AIP Publishing LLC.
Single-shot detection of mid-infrared spectra by chirped-pulse upconversion with four-wave difference frequency generation in gases
(2013-07-29)
Nomura, Y.
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Wang, Y. -T.
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Kozai, T.
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Shirai, H.
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Yabushita, A.
Single-shot detection of ultrabroadband mid-infrared spectra was demonstrated by using chirped-pulse upconversion technique with four-wave difference frequency generation in gases. Thanks to the low dispersion of the gas media, the bandwidth of the phase matching condition of the upconversion process becomes very broad and the entire mid-infrared spectrum spanning from 200 to 5500 cm(-1) was upconverted by using a 10 ps chirped pulse to visible wavelength radiation, which was detected with a conventional visible dispersive spectrometer. This method was demonstrated by the successful measurement of infrared absorption spectra of organic polymer films. (C) 2013 Optical Society of America
Dual-port subthreshold SRAM cell
(2013-07-30)
Chiu Yi-Te
;
Chang Ming-Hung
;
Yang Hao-I
;
Hwang Wei
An innovative dual-port subthreshold static random access memory (SRAM) cell for sub-threshold voltage operation is disclosed. During write mode, the dual-port subthreshold SRAM cell would cut off the positive feedback loop of the inverters and utilize the reverse short-channel effect to enhance write capability. The single-ended read/write port structure further reduces power consumption of the lengthy bit line. Therefore, the dual-port subthreshold SRAM cell is a suitable for long operation in a first-in first-out memory system. Although the lower voltage reduces the stability of the memory cell, the dual-port subthreshold SRAM cell of the present invention can still stably operate.
Vibrational and electronic relaxation in MEH-PPV using few cycle pulses
(2013-07-30)
Kobayashi, Takayoshi
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Yamashita, Munenori
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Du, Juan
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Zhang, Jun
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Iwakura, Izumi
The electronic population decay time is determined to be about 500 fs in (poly-[2-methoxy-5-(2'-ethyl-hexyloxy)-p-phenylenevinylenel (MEH-PPV) using 5.7 fs pulses. The ultrafast electronic dephasing time and the self-trapping time of free exciton to form an exciton polaron is determined as 25 +/- 2 fs and 50 +/- 23 fs, respectively. Real-time spectrogram analysis reveals dynamic mode coupling among the high-frequency and low-frequency modes. The energy-ladder descent vibrational process is clarified using the first moment of the difference absorption spectrum. The phase relaxation time is calculated from the widths of the Fourier spectra of several strongly coupled modes. (C) 2013 Elsevier B.V. All rights reserved.
Strain enhanced ferroelectric properties of multiferroic BiFeO3/SrTiO3 superlattice structure prepared by radio frequency magnetron sputtering
(2013-07-31)
Chiu, Shang-Jui
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Liu, Yen-Ting
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Lee, Hsin-Yi
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Yu, Ge-Ping
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Huang, Jia-Hong
Asymmetric superlattice structures consisting of SrTiO3 (STO) and multiferroic BiFeO3 (BFO) sublayers were deposited on a Nb-doped STO (001) substrate with a radio frequency magnetron sputtering system. For an investigation of the effect of strain on the microstructures, ferroelectric properties and piezoelectric properties resulting from a difference of lattice parameters of the BFO sublayer, varying the thickness of the STO sublayer in a range 1-2.5 nm introduced interfacial strain into the superlattice. The epitaxial relation and strain state of films were clearly observed with a synchrotron as a source of radiation. The results of X-ray diffraction measurements clearly showed that the decrease of strain was related to the thickness of the STO substrate. A separate diffraction signal of the superlattice structure with thickness >= 1.75 nm of the STO sublayer was found, indicating a large strain relaxation in these superlattice films. The remnant polarization values P-r, piezoelectric coefficient d(33) and leakage properties of the BFO/STO superlattice thin films that improved with increasing in-plane strain provide strong evidence of a strain-enhancement effect. The BFO/STO superlattice with a well defined crystal structure and a large strain state showed a large P-r, greater than a BFO single layer of the same thickness. (C) 2013 Elsevier B.V. All rights reserved.
A novel approach to collaborative testing in a crowdsourcing environment
(2013-08-01)
Tung, Yuan-Hsin
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Tseng, Shian-Shyong
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資訊工程學系
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Department of Computer Science
Software testing processes are generally labor-intensive and often involve substantial collaboration among testers, developers, and even users. However, considerable human resource capacity exists on the Internet in social networks, expert communities, or internet forums-referred to as crowds. Effectively using crowd resources to support collaborative testing is an interesting and challenging topic. This paper defines the collaborative testing problem in a crowd environment as an NP-Complete job assignment problem and formulates it as an integer linear programming (ILP) problem. Although package tools can be used to obtain the optimal solution to an ILP problem, computational complexity makes these tools unsuitable for solving large-scale problems. This study uses a greedy approach with four heuristic strategies to solve the problem. This is called the crowdsourcing-based collaborative testing approach. This approach includes two phases, training phase and testing phase. The training phase transforms the original problem into an ILP problem. The testing phase solves the ILP using heuristic strategies. A prototype system, called the Collaborative Testing System (COTS), is also implemented. The experiment results show that the proposed heuristic algorithms produce good quality approximate solutions in an acceptable timeframe. (c) 2013 Elsevier Inc. All rights reserved.