Browsing by Issue Date, starting with "2011-06-24"

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Non-volatile domain nucleation and growth in multiferroic BiFeO(3) films
(2011-06-24)
Chen, Yi-Chun
;
Wang, Guang-Fu
;
Tai, Hsiang-Hua
;
Chen, Jhih-Wei
;
Huang, Yen-Chin
We have presented a systematical study of the domain nucleation and growth behaviors in multiferroic BiFeO(3) (BFO) films. Both the ferroelectric and the ferroelastic switching dynamics were investigated. Several environmental parameters, including the polarization orientations, the monodomain-like matrix, and the ordered domain walls as local boundaries, were well controlled by thin-film strain engineering through changing the vicinal angles of the substrates. The tip-based domain dynamics was studied by subsequent piezoresponse force microscope (PFM) imaging of the domain evolution under external voltage pulses. For the nanodomains written in the monodomain-like environment, the domain wall performed the thermal activated motion. The as-grown 71 degrees domain walls can act as pinning centers for the ferroelectric domain growth driven by low fields; moreover, ferroelastic nucleation near a 71 degrees domain wall will cause the deformation of the domain wall. The ferroelastic domain growth possessed relatively small activation fields, and therefore usually performed non-activated motion. This study revealed the effects of local environments on the dynamics forming nanoscale domains, and opened a pathway for applications in novel non-volatile functional devices.
Non-volatile domain nucleation and growth in multiferroic BiFeO3 films
(2011-06-24)
Chen, Yi-Chun
;
Wang, Guang-Fu
;
Tai, Hsiang-Hua
;
Chen, Jhih-Wei
;
Huang, Yen-Chin
We have presented a systematical study of the domain nucleation and growth behaviors in multiferroic BiFeO3 (BFO) films. Both the ferroelectric and the ferroelastic switching dynamics were investigated. Several environmental parameters, including the polarization orientations, the monodomain-like matrix, and the ordered domain walls as local boundaries, were well controlled by thin-film strain engineering through changing the vicinal angles of the substrates. The tip-based domain dynamics was studied by subsequent piezoresponse force microscope (PFM) imaging of the domain evolution under external voltage pulses. For the nanodomains written in the monodomain-like environment, the domain wall performed the thermal activated motion. The as-grown 71 degrees domain walls can act as pinning centers for the ferroelectric domain growth driven by low fields; moreover, ferroelastic nucleation near a 71 degrees domain wall will cause the deformation of the domain wall. The ferroelastic domain growth possessed relatively small activation fields, and therefore usually performed non-activated motion. This study revealed the effects of local environments on the dynamics forming nanoscale domains, and opened a pathway for applications in novel non-volatile functional devices.
Observation of Significant enhancement in the efficiency of a DSSC by InN nanoparticles over TiO(2)-nanoparticle films
(2011-06-24)
Wang, Tsai-Te
;
Raghunath, P.
;
Lu, Yun-Fang
;
Liu, Yu-Chang
;
Chiou, Chwei-Huawn
We have studied the effect of InN deposited over TiO(2) nanoparticle (NP) films on the performance of dye-sensitized solar cells (DSSCs) using N3 dye with I(-)/I(3)(-) electrolyte. A 10-20% increase in efficiency was observed for InN deposited, N3 sensitized 5-8.5 mu m thick TiO(2) films as compared to similar non-treated films. The deposition of InN was carried out in the temperature range of 573-723 K organometallic chemical vapor deposition (OMCVD). Spectral shifts and DFT calculations with a model anchoring group (R'COOH) both suggest binding of the N3 dye directly to both InN and the InN/TiO(2) sites. (C) 2011 Elsevier B.V. All rights reserved.
Observation of Significant enhancement in the efficiency of a DSSC by InN nanoparticles over TiO2-nanoparticle films
(2011-06-24)
Wang, Tsai-Te
;
Raghunath, P.
;
Lu, Yun-Fang
;
Liu, Yu-Chang
;
Chiou, Chwei-Huawn
We have studied the effect of InN deposited over TiO2 nanoparticle (NP) films on the performance of dye-sensitized solar cells (DSSCs) using N3 dye with I-/I-3(-) electrolyte. A 10-20% increase in efficiency was observed for InN deposited, N3 sensitized 5-8.5 mu m thick TiO2 films as compared to similar non-treated films. The deposition of InN was carried out in the temperature range of 573-723 K organometallic chemical vapor deposition (OMCVD). Spectral shifts and DFT calculations with a model anchoring group (R'COOH) both suggest binding of the N3 dye directly to both InN and the InN/TiO2 sites. (C) 2011 Elsevier B.V. All rights reserved.
Wide-field Rayleigh scattering imaging and spectroscopy of gold nanoparticles in heavy water under laser trapping
(2011-06-25)
Uwada, Takayuki
;
Sugiyama, Teruki
;
Masuhara, Hiroshi
;
應用化學系
;
應用化學系分子科學碩博班
We demonstrated wide-field Rayleigh scattering spectroscopy and imaging of gold nanoparticle trapping upon a focused near-infrared laser irradiation under dark-field illumination. The migration, trapping, and assembling behavior of gold nanoparticles were examined at single nanoparticle level at the focus spot and its surrounding area in heavy water. It is clarified that particle migration to the laser spot within the focal plane is not appreciable while scattering force drives the migration vertically along the direction of light propagation. The gradient force at the focus point and the scattering force are theoretically estimated to be 3.1 and 0.17 pN, which are consistent with the direct observation. Analysis of light scattering intensity fluctuation at the focus shows that three nanoparticles can be trapped at most, which is well supported by light scattering spectral measurement. The particle existence probability at the focus is estimated as a function of lateral distance from the focus, and is compared with numerically obtained photon pressure potential. (C) 2011 Elsevier B.V. All rights reserved.
Organic photosensitive optoelectronic device
(2011-06-28)
Meng Hsin-Fei
;
Hong Sheng-Fu
;
Tseng Hsin-Rong
;
Chen En-Chen
;
Chu Chia-Hung
An organic photosensitive optoelectronic device includes an anode, an organic photosensitive layer formed on the anode and having a donor portion and an acceptor portion, a hole blocking layer formed on the organic photosensitive layer so as for the organic photosensitive layer to be sandwiched between the anode and the hole blocking layer, and a cathode formed on the hole blocking layer so as for the hole blocking layer to be sandwiched between the cathode and the organic photosensitive layer. The highest occupied molecular orbitals (HOMO) of the hole blocking layer is at least 0.3 eV higher than that of the donor portion. Therefore, the optoelectronic device efficiently suppresses dark current so as to enhance sensitivity when applied to a detector.
DEREVERBERATION AND NOISE REDUCTION METHOD FOR MICROPHONE ARRAY AND APPARATUS USING THE SAME
(2011-06-30)
Bai Mingsian R.
;
Hur Ker-Nan
;
Liou Ying-Ting
A dereverberation and noise reduction method adapted for a microphone array and an apparatus using the same are proposed. The microphone array receives a plurality of audio signals from an audio source. The dereverberation and noise reduction method includes the following steps. The received audio signals are processed by a beamforming processing, and a first audio signal is generated. Besides, the received audio signals are processed by a suppression processing, and a suppression audio vector is generated. Further, suppression audio vector is processed by an adaptive filtering processing, and a second audio signal is generated. In addition, the second audio signal is subtracted from the first audio signal to acquire an audio output signal, where parameters of the adaptive filtering processing are adjusted according to a feedback of the audio output signal.
High Electron Mobility Transistor and Method for Fabricating the Same
(2011-06-30)
Chang Edward Yi
;
Kuo Chien-I
;
Hsu Heng-Tung
A high electron mobility transistor includes a substrate, a buffer layer, a channel layer, a spacer layer, a schottky layer and a cap layer. The buffer layer is formed on the substrate. The channel layer is formed on the buffer layer, in which the channel layer comprises a superlattice structure formed with a plurality of indium gallium arsenide thin films alternately stacked with a plurality of indium arsenide thin films. The spacer layer is formed on the channel layer. The schottky layer is formed on the spacer layer. The cap layer is formed on the schottky layer.
Method for preparing organic light emitting diode and device thereof
(2011-06-30)
Hsu Chain-Shu
;
Meng Hsin-Fei
;
Horng Sheng-Fu
;
Zan Hsiao-Wen
;
Tseng Hsin-Rong
A method for fabricating an organic light emitting diode and a device thereof are provided. The method includes: providing a substrate; dispensing to the substrate a second organic molecule solution resulting from dissolving a second organic molecule in a solvent; applying the second organic molecule solution to a surface of the substrate so as to form a wet film layer; and heating the wet film layer by a heating unit to remove the solvent therefrom and thereby form a second organic molecule film. The method is effective in fabricating a uniform multilayer structure for use in fabrication of large-area photoelectric components.
X-ray effects on the oxidation of Cu nanoparticles
(2011-06-30)
Chen, Chun-Hua
;
Koga, Kenji
;
材料科學與工程學系
;
Department of Materials Science and Engineering
X rays have been widely used for nondestructive analysis of nano-scaled materials for a long time; however, the effects of x-ray radiation have been less extensively discussed. In this work, by means of the in-situ x-ray diffraction and the ex-situ high-resolution electron microscopy, we have quantitatively investigated the x-ray effect on the oxidation behavior of Cu nanoparticles prepared by the vapor condensation method. Clear evidence shows that the x-ray irradiation increases the oxidation thickness as well as the oxidation rate. The results are of critical importance not only for the oxidation studies but also for the nanomaterial researches with x-ray related equipment. (C) 2011 Elsevier B.V. All rights reserved.
REACTOR, CHEMICAL VAPOR DEPOSITION REACTOR, AND METALORGANIC CHEMICAL VAPOR DEPOSITION REACTOR
(2011-06-30)
CHEN Wei-Kuo
;
CHEN Ching-Yu
A reactor for film deposition having a first heating unit and the second heating units is described. The temperature of each heating unit is controlled individually by heating and/or cooling means. The first heating unit and the second heating unit are disposed face-to-face to each other to form a reaction region therein, and their inner sides are placed with an inclined angle. At least one substrate is disposed on the inner surface of the first heating unit. The temperature of the second heating unit can be adapted to a temperature higher than the temperature of the first heating unit to improve the thermal decomposition efficiency of input reactants so that a low-temperature film deposition can be accomplished.
Second-Order Extended H-infinity Filter for Nonlinear Discrete-Time Systems Using Quadratic Error Matrix Approximation
(2011-07-01)
Hu, Jwu-Sheng
;
Yang, Chia-Hsing
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
In this paper, the second-order extended (SOE) H-infinity filter for nonlinear discrete-time systems is derived based on an approximation to the quadratic error matrix. The solution is obtained by the game theory approach. It is shown that the result bears a strong resemblance to the SOE Kalman filter when the performance bound goes to infinity. An example of vehicle state tracking is simulated to compare the performances of the SOE Kalman filter, the first order extended and the SOE H-infinity filter. Noises with unknown bias are injected into both process dynamics and measurements. The results show that the SOE H-infinity filter has the smallest state tracking error.
The Growth of an Epitaxial ZnO Film on Si(111) with a Gd(2)O(3)(Ga(2)O(3)) Buffer Layer
(2011-07-01)
Lin, B. H.
;
Liu, W. R.
;
Yang, S.
;
Kuo, C. C.
;
Hsu, C. -H.
High-quality (0001)-oriented ZnO epitaxial films have been grown by pulsed laser deposition on Si(111) buffered with a nanometer-thick Gd(2)O(3)(Ga(2)O(3)), GGO, layer. The structural characteristics of the ZnO epi-layers were studied by X-ray diffraction and transmission electron microscopy (TEM). The in-plane epitaxial relationship between the wurtzite ZnO, cubic GGO, and cubic Si follows {10 (1) over bar0}(ZNO)parallel to{4 (22) over bar}(Gd2O3)parallel to{(4) over bar 22}(Si) and the ZnO/GGO interface can be described by the domain matching epitaxy. TEM contrast analysis reveals that the major defect structures in the ZnO films are edge-type threading dislocations and intrinsic basal plane stacking faults. All the ZnO epi-films studied are under a tensile biaxial strain, but no cracks were found. Temperature-dependent photoluminescence results show the excellent optical properties of the obtained ZnO layers, and the origins of the spectral features are discussed.
A two-phase algorithm for product part change utilizing AHP and PSO
(2011-07-01)
Huang, P. C.
;
Tong, L. I.
;
Chang, W. W.
;
Yeh, W. C.
;
工業工程與管理學系
This study presents a two-phase algorithm approach to deal with the issue of product part change, and the issue of supplier selection derived from the former. In the first step, Analytical Hierarchy Process (AHP) was used on expert interview records to select the module in a product that needs to be changed with top priority. In the second step, after changing the module, the supplier selection process, including building a mathematical programming model, was initiated to select the best suppliers using Particle Swarm Optimization (PSO) algorithm. We tried to use this method to maximize the value of product updating so as to extend the product life cycle, under the conditions of limited resource, and keeping the scope of change to a minimum. Finally, we selected a switchboard manufacturer as a case study to test the proposed algorithm. Crown Copyright (C) 2011 Published by Elsevier Ltd. All rights reserved.
First principles study of the electron density distribution in a pair of bare metallic electrodes
(2011-07-01)
Ma, Chun-Lan
;
Chen, Yu-Chang
;
Nghiem, Diu
;
Tseng, Allen
;
Huang, Pao-Chieh
Self-consistent calculations of electron density distribution from first principles for a series of semi-infinite metals show that the electron density almost drops to zero at 8.5 a.u. away from a metal surface. The electron densities in a series of bimetallic-electrode systems with a distance between the two electrodes of 21.7 a.u. are further investigated. Spin-polarized calculations of electron density for nonmagnetic and magnetic bimetallic-electrode systems are compared. Our work is helpful for first principles investigation of spin-dependent metal-molecule-metal tunneling junctions.
Improving electrical characteristics of W/HfO2/In0.53Ga0.47As gate stacks by altering deposition techniques
(2011-07-01)
Zade, D.
;
Kakushima, K.
;
Kanda, T.
;
Lin, Y. C.
;
Ahmet, P.
The effects of controlling InGaAs substrate temperature during electron beam deposition of HfO2 on electrical characteristics of W/HfO2/n-In0.53Ga0.47As capacitors are investigated. It is found that by depositing a thin HfO2 layer at the interface when substrate temperature is raised to 300 degrees C, frequency dispersion at depletion and accumulation conditions is reduced and interface state density is lowered regardless of the HfO2 thickness. Cross-sectional transmission electron microscopy images have revealed that the formation of mesoscopic voids in the InGaAs substrate near the interface is suppressed with HfO(2)deposition at 300 degrees C at the interface. A band diagram with an additional bulk trap energy level has been proposed to explain the frequency dispersion and conductance peaks at accumulation condition. (c) 2011 Elsevier B.V. All rights reserved.
Improved characteristics for Pd nanocrystal memory with stacked HfAlO-SiO2 tunnel layer
(2011-07-01)
Kang, Tsung-Kuei
;
Liu, Han-Wen
;
Wang, Fang-Hsing
;
Lin, Cheng-Li
;
Liao, Ta-Chuan
Stacked HfAlO-SiO2 tunnel layers are designed for Pd nanocrystal nonvolatile memories. For the sample with 1.5 nm-HfAlO/3.5 nm-SiO2 tunnel layer, a smaller initial memory window is obtained compared to the sample with 3.5 nm-HfAlO/1.5 nm-SiO2 tunnel layer. Owing to the thermally induced traps in HfAlO-SiO2 films are located at a farther distance from the Si substrate and more effective blocking of charge leakage by asymmetric tunnel barrier, a larger final memory window and better retention characteristic can be obtained for Al/blocking oxide SiO2/Pd NC5/1.5 nm-HfAlO/3.5 nm-SiO2/Si structure. A N-2 plasma treatment can further improve the memory characteristics. Better memory characteristics can be obtained for Pd-nanocrystal-based nonvolatile memory with an adequate thickness ratio of HfAlO to SiO2. (C) 2011 Elsevier Ltd. All rights reserved.
PAComplex: a web server to infer peptide antigen families and binding models from TCR-pMHC complexes
(2011-07-01)
Liu, I-Hsin
;
Lo, Yu-Shu
;
Yang, Jinn-Moon
;
生物科技學系
;
生物資訊及系統生物研究所
One of the most adaptive immune responses is triggered by specific T-cell receptors (TCR) binding to peptide-major histocompatibility complexes (pMHC). Despite the availability of many prediction servers to identify peptides binding to MHC, these servers are often lacking in peptide-TCR interactions and detailed atomic interacting models. PAComplex is the first web server investigating both pMHC and peptide-TCR interfaces to infer peptide antigens and homologous peptide antigens of a query. This server first identifies significantly similar TCR-pMHC templates (joint Z-value >= 4.0) of the query by using antibody-antigen and protein-protein interacting scoring matrices for peptide-TCR and pMHC interfaces, respectively. PAComplex then identifies the homologous peptide antigens of these hit templates from complete pathogen genome databases (>= 10(8) peptide candidates from 864 628 protein sequences of 389 pathogens) and experimental peptide databases (80 057 peptides in 2287 species). Finally, the server outputs peptide antigens and homologous peptide antigens of the query and displays detailed interacting models (e.g. hydrogen bonds and steric interactions in two interfaces) of hitTCR-pMHC templates. Experimental results demonstrate that the proposed server can achieve high prediction accuracy and offer potential peptide antigens across pathogens. We believe that the server is able to provide valuable insights for the peptide vaccine and MHC restriction. The PAComplex sever is available at http://PAcomplex.life.nctu.edu.tw.
Characterisation of a suspended nanowire channel thin-film transistor with sub-100 nm air gap
(2011-07-01)
Kuo, Chia-Hao
;
Hsu, Chia-Wei
;
Lin, Horng-Chih
;
Huang, Tiao-Yuan
;
電子工程學系及電子研究所
A novel suspended nanowire (NW) channel thin-film transistor (TFT) with sub-100 nm air gap has been fabricated and characterised. With a simple and low-cost over-etching-time-controlled reactive ion etching technique and a buffered-oxide etch wet-etching process, a suspended NW of 27 nm and an air gap of 10 nm were achieved. The resultant suspended-NW-channel TFTs showed an ultra-low subthreshold swing (52 mV/dec) and considerable hysteresis window (3.7 V). Finally, the impacts of device dimensions on the characteristics of suspended NW TFTs were also investigated.
High-Quality 1 eV In0.3Ga0.7As on GaAs Substrate by Metalorganic Chemical Vapor Deposition for Inverted Metamorphic Solar Cell Application
(2011-07-01)
Hong Quan Nguyen
;
Chang, Edward Yi
;
Yu, Hung Wei
;
Lin, Kung Liang
;
Chung, Chen Chen
In0.3Ga0.7As layers were grown by metalorganic chemical vapor deposition using step graded buffer layers on different misoriented GaAs(001) substrates. Smooth-surface In0.3Ga0.7As film with a root mean square roughness of 1.9 nm was obtained with the growth temperature of 490 degrees C using a 10-step graded parabolic-like indium profile buffer layer on the surface with the 6 degrees-off cut toward the [111] direction. The threading dislocation density in the film was determined to be 1.2 x 10(6) cm(-2) by transmission electron microscopy. The photoluminescence results obtained at 300 and 77K indicate that very low recombination centers existed in the epilayer. (C) 2011 The Japan Society of Applied Physics