Browsing by Issue Date, starting with "2008-11-15"

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Magnetic ordering anisotropy in epitaxial orthorhombic multiferroic YMnO(3) films
(2008-11-15)
Hsieh, C. C.
;
Lin, T. H.
;
Shih, H. C.
;
Hsu, C. -H.
;
Luo, C. W.
Orthorhombic YMnO(3) thin films with (200), (020), and (001) orientations were, respectively, obtained by pulsed laser deposition on SrTiO(3)(110), LaAlO(3)(110), and SrTiO(3)(001) substrates. The results demonstrate that the strain between film and substrate can serve as an alternative in transforming the thermodynamically stable hexagonal YMnO(3) into the orthorhombic phase, which previously could be obtained with high-pressure high temperature syntheses and epitaxy-stabilized thin film processes. More importantly, these films allow us, for the first time, to unambiguously disclose the intrinsic magnetic property along different crystallographic orientations. Our results show that, although the antiferromagnetic (AFM) ordering remains the same, there is an additional spin reordering transition which is very much dependent on the crystallographic orientation along which the measuring field was applied and on the in-plane crystallographic alignment of the films. Detailed analyses indicate that the origin of the observed second reordering may be due to some strain-induced canted AFM state instead of the incommensurate lock-in transitions conceived previously.
Improving segmentation accuracy for magnetic resonance imaging using a boosted decision tree
(2008-11-15)
Chao, Wen-Hung
;
Chen, You-Yin
;
Cho, Chien-Wen
;
Lin, Sheng-Huang
;
Shih, Yen-Yu I.
The purpose of this study was to improve the accuracy rate of brain tissue classification in magnetic resonance (MR) imaging using a boosted decision tree segmentation algorithm. Herein. we examined simulated phantom MR (SPMR) images, simulated brain MR (SBMR) images, and a real data. The accuracy rate and k index when classifying brain tissues as gray matter (GM), white matter (WM), or cerebral-spinal fluid (CSF) were better when using the boosted decision tree algorithm combined with a fuzzy threshold than when using a statistical region-growing (SRG) algorithm [Wolf 1, Vetter M, Wegner 1, Bottger T, Nolden M, Schobinger M, et al. The medical imaging interaction toolkit. Med Imag Anal 2005;9:594-604] and an adaptive segmentation (AS) algorithm [Wells WM, Crimson WEL, Kikinis R, Jolesz FA. Adaptive segmentation of MRI data. IEEE Trans Med Imag 1996; 15:429-42]. The segmentation performance when using this algorithm on real data from brain MR images was also better than those of SRG and AS algorithm. Segmentation of a real data using the boosted decision tree produced particularly clear brain MR imaging and permitted more accurate brain tissue segmentation. In conclusion, a decision tree with appropriate boost trials successfully improved the accuracy rate of MR brain tissue segmentation. Crown Copyright (C) 2008 Published by Elsevier B.V. All rights reserved.
Efficiency enhancement of UV/blue light emitting diodes via nanoscaled epitaxial lateral overgrowth of GaN on a SiO(2) nanorod-array patterned sapphire substrate
(2008-11-15)
Chiu, C. H.
;
Li, Zhen-Yu
;
Chao, C. L.
;
Lo, M. H.
;
Kuo, H. C.
High-quality GaN layer was successfully grown on a SiO(2) nanorod-array patterned sapphire substrate (NAPSS) using metal-organic chemical vapor deposition by a nanoscaled epitaxial lateral overgrowth (NELO) method. From tunneling electron microscope images, well coalescence and turned dislocations are parallel to the surface direction were clearly observed. The Raman shift measurement shows the residual stress in GaN was greatly reduced from 1.359 to 0.652 GPa when compared to a GaN on flat sapphire substrate. Also, a high-efficiency GaN-based light-emitting diodes (LEDs) were demonstrated on the NELO NAPSS GaN, the respective output power and external quantum efficiency of the NELO NAPSS LEDs were estimated to be 22 mW and 40.2% at an injection current of 20 mA, showing an enhancement factor of 52% over conventional LEDs. The significant improvement resulted from both the enhanced light extraction assisted by the NAPSS, and the reduced dislocation densities using the NELO method. (c) 2008 Published by Elsevier B.V.
Efficiency enhancement of UV/blue light emitting diodes via nanoscaled epitaxial lateral overgrowth of GaN on a SiO2 nanorod-array patterned sapphire substrate
(2008-11-15)
Chiu, C. H.
;
Li, Zhen-Yu
;
Chao, C. L.
;
Lo, M. H.
;
Kuo, H. C.
High-quality GaN layer was successfully grown on a SiO2 nanorod-array patterned sapphire substrate (NAPSS) using metal-organic chemical vapor deposition by a nanoscaled epitaxial lateral overgrowth (NELO) method. From tunneling electron microscope images, well coalescence and turned dislocations are parallel to the surface direction were clearly observed. The Raman shift measurement shows the residual stress in GaN was greatly reduced from 1.359 to 0.652 GPa when compared to a GaN on flat sapphire substrate. Also, a high-efficiency GaN-based light-emitting diodes (LEDs) were demonstrated on the NELO NAPSS GaN, the respective output power and external quantum efficiency of the NELO NAPSS LEDs were estimated to be 22 mW and 40.2% at an injection current of 20 mA, showing an enhancement factor of 52% over conventional LEDs. The significant improvement resulted from both the enhanced light extraction assisted by the NAPSS, and the reduced dislocation densities using the NELO method. (c) 2008 Published by Elsevier B.V.
High-reflectivity ultraviolet AlN/AlGaN distributed Bragg reflectors grown by metalorganic chemical vapor deposition
(2008-11-15)
Chen, Jun-Rong
;
Ling, Shih-Chun
;
Hung, Chin-Tsang
;
Ko, Tsung-Shine
;
Lu, Tien-Chang
High-reflectivity ultraviolet distributed Bragg reflectors (DBRs), based on AlN/AlGaN quarter-wave layers, have been designed and grown on 2 in (0001) sapphire substrates by metalorganic chemical vapor deposition. The growth of 20-pair AlN/Al(0.23)Ga(0.77)N DBR shows no observable cracks in the structure and achieves peak reflectivity of 90% at 367 nm together with a stop-band width of 24 nm. Furthermore, the growth of 34-pair AlN/Al(0.23)Ga(0.77)N DBR shows partial cracks from optical microscopy images. According to the room-temperature photoluminescence measurement, the ennission spectrum of 34-pair AlN/Al(0.23)Ga(0.77)N DBR is broader than that of 20-pair AlN/Al(0.23)Ga(0.77)N DBR, which Could be due to strain inhomogeneity generated by cracks. Despite the crystal quality problem, the peak reflectivity of 34-pair AlN/Al(0.23)Ga(0.77)/N DBR could still achieve 97% at 358 nm and the stop-band width is 16nm. (C) 2008 Elsevier B.V. All rights reserved.
Strain relaxation in InAs self-assembled quantum dots induced by a high N incorporation
(2008-11-15)
Chen, J. F.
;
Yang, C. H.
;
Wu, Y. H.
;
Chang, L.
;
Chi, J. Y.
The effect of a high N incorporation in self-assembled InAs quantum dots (QDs) is investigated by analyzing the electronic and structural properties around QD region. Capacitance-voltage profiling and admittance spectroscopy shows that N incorporation into the InAs QD layer leads to drastic carrier depletion in the QD layer and neighboring GaAs layers due to the formation of a deep defect state at 0.34-0.41 eV. The signature of this defect state is similar to those defects observed in strain relaxed QDs or InGaAs/GaAs quantum wells when the InAs deposition thickness exceeds a critical thickness. Accordingly, the N incorporation might result in strain relaxation either by increasing localized strain or by inducing composition inhomogeneities, which provide nucleation sources for strain relaxation. The argument of strain relaxation is supported by transmission electron microscopy that reveals lattice misfits at the QD layer and neighboring GaAs layers.
Characteristics of a-plane GaN with the SiNx insertion layer grown by metal-organic chemical vapor deposition
(2008-11-15)
Ko, T. S.
;
Wang, T. C.
;
Huang, H. M.
;
Chen, J. R.
;
Chen, H. G.
We utilized in-situ-grown SiNx insertion layers to mitigate part of dislocations stretching in nonpolar a-plane GaN films using metal-organic chemical vapor deposition. Both X-ray diffraction (XRD) and atomic force microscopy (AFM) measurements revealed that better crystal quality and smoother surface could be obtained when the in-situ SiNx layer was inserted closer to the r-plane sapphire substrate and indicated that the in-situ SiNx insertion layer could suppress dislocations caused by lattice mismatch between the sapphire and epitaxial layers. In addition, photoluminescence and cathodoluminescence measurements confirmed the effect of the in-situ SiNx insertion layer on the optical properties of the improved a-plane GaN thin film, which is consistent with the XRD and AFM analyses and suggested reduction in the density of nonradiative centers. (C) 2008 Elsevier B.V. All rights reserved.
Electric-field-controlled electron relaxation in lateral double quantum dots embedded in a suspended slab
(2008-11-15)
Liao, Y. Y.
;
Chuu, D. S.
;
Jian, S. R.
;
電子物理學系
;
Department of Electrophysics
This study investigates phonon-induced electron relaxation in a lateral double quantum dot that is embedded in a suspended slab. Exact calculations are made in electric fields. The dependence of the relaxation rate on the parameters of the dots and the slabs is analyzed. Numerical results indicate that the relaxation rate depends strongly on the phonon character of the slab. Unlike in the bulk environment, phonon-subband quantization clearly influences the behavior. In particular, the relaxation rate can be greatly suppressed or enhanced by tuning the electric fields. This fact may be useful in manipulating the relaxation rate in lateral double quantum dots.
Characteristics of a-plane GaN with the SiN(x) insertion layer grown by metal-organic chemical vapor deposition
(2008-11-15)
Ko, T. S.
;
Wang, T. C.
;
Huang, H. M.
;
Chen, J. R.
;
Chen, H. G.
We utilized in-situ-grown SiN(x) insertion layers to mitigate part of dislocations stretching in nonpolar a-plane GaN films using metal-organic chemical vapor deposition. Both X-ray diffraction (XRD) and atomic force microscopy (AFM) measurements revealed that better crystal quality and smoother surface could be obtained when the in-situ SiN(x) layer was inserted closer to the r-plane sapphire substrate and indicated that the in-situ SiN(x) insertion layer could suppress dislocations caused by lattice mismatch between the sapphire and epitaxial layers. In addition, photoluminescence and cathodoluminescence measurements confirmed the effect of the in-situ SiN(x) insertion layer on the optical properties of the improved a-plane GaN thin film, which is consistent with the XRD and AFM analyses and suggested reduction in the density of nonradiative centers. (C) 2008 Elsevier B.V. All rights reserved.
Magnetic ordering anisotropy in epitaxial orthorhombic multiferroic YMnO3 films
(2008-11-15)
Hsieh, C. C.
;
Lin, T. H.
;
Shih, H. C.
;
Hsu, C. -H.
;
Luo, C. W.
Orthorhombic YMnO3 thin films with (200), (020), and (001) orientations were, respectively, obtained by pulsed laser deposition on SrTiO3(110), LaAlO3(110), and SrTiO3(001) substrates. The results demonstrate that the strain between film and substrate can serve as an alternative in transforming the thermodynamically stable hexagonal YMnO3 into the orthorhombic phase, which previously could be obtained with high-pressure high temperature syntheses and epitaxy-stabilized thin film processes. More importantly, these films allow us, for the first time, to unambiguously disclose the intrinsic magnetic property along different crystallographic orientations. Our results show that, although the antiferromagnetic (AFM) ordering remains the same, there is an additional spin reordering transition which is very much dependent on the crystallographic orientation along which the measuring field was applied and on the in-plane crystallographic alignment of the films. Detailed analyses indicate that the origin of the observed second reordering may be due to some strain-induced canted AFM state instead of the incommensurate lock-in transitions conceived previously.
跨越障礙之載具
(2008-11-16)
鄭璧瑩
;
郭芳富
;
黃健寶
;
林奕仲
;
李育賢
本發明係提供一種跨越障礙之載具,係用於載運乘客或其他負荷的支座;一感測調整模組用於偵測該支座傾斜之狀態與維持該支座之水平;一地面接觸模組,設置於該支座下,其支撐一有效載重,並可抬舉該支座跨越一障礙之一表面,與一無線訊號接收發射模組做結合,可藉由該無線訊號接收發射器蒐集與傳送資訊,來做出相對應其內部狀況所須之調整與動作,達成一具有安全、穩定、可靠、舒適、便利、成本低的跨越障礙之載具。
用於白光光源之新穎螢光體與其製造方法
(2008-11-16)
陳登銘
;
張峻魁
本發明係提供一種用於白光光源之新穎螢光體組成物,係為下列一般式所示:(Ml-m-nCemEun)2BO3X 其中M為選自於Ca、Sr、Ba所組成之群組中至少一元素、X為選自於Cl、Br所組成之群組中至少一元素,且m之數値範圍為0≦m≦0.5,以及n之數値範圍為0≦n≦0.5。
感測裝置
(2008-11-16)
鄭璧瑩
;
黃健寶
本發明係提供一種感測裝置,係應用一半球形容器裝載液態介電質,利用半球形容器內兩對以上之電極端,以供液態介電質觸發電極來導通電路,而此容器外圍是以抗腐蝕材料包覆之;一緩衝頸縮口及一精度閥,設置於容器上,以避免該液態介電質與電極產生接觸,達成避免震動之干擾及調節液態介電質的液面高度改變感測裝置之靈敏度;以及一防漏感測裝置,係包覆半球形容器、液態介電質、緩衝頸縮口、精度閥,以防止該液態介電質洩漏,達成一個多方向可控制、偵測、調整傾斜功能之感測器。
微波退火提升有機電子元件特性之方法
(2008-11-16)
陳方中
;
葛祖榮
;
林義凱
本發明為一種微波退火提升有機電子元件特性之方法,包括下列步驟:提供有機電子元件;以及微波退火有機電子元件。因為微波退火具有非接觸式、退火標的具選擇性、以及退火時間短等特性,且可以僅針對有機電子元件的有機主動層(Organic active layer)退火,使得有機主動層內的有機分子在短時間內重新排列以提高有機分子的排列程度,進而增加光電轉換效率,並提升有機電子元件的特性。
Electrical bistable memory device based on a poly(styrene-b-4-vinylpyridine) nanostructured diblock copolymer thin film
(2008-11-17)
Huang, Ching-Mao
;
Liu, Yung-Sheng
;
Chen, Chen-Chia
;
Wei, Kung-Hwa
;
Sheu, Jeng-Tzong
This paper describes the performance of a nonvolatile memory device based on a solution-processed poly(styrene-b-4-vinylpyridine) (PS-b-P4VP) diblock copolymer thin film. The Al/PS-b-P4VP/indium tin oxide memory device featuring metal-coordinated 30 nm P4VP cores exhibited an ON/OFF ratio of 2x10(5), an erase voltage of 0.75 V, a write voltage of -0.5 V, and a retention time of 10(4) s. The device exhibited a metallic behavior in the ON state, suggesting the formation of metallic filaments through the migration of Al atoms into the P4VP domain during writing. Such nanostructured diblock copolymer thin films open up avenues for fabricating organic memory devices using simple procedures.
企業家與社會責任
(2008-11-18)
林家和
;
開放教育推動中心
;
Open Education Office
課程日期： 2008年11月18日(三) 演講人：林家和先生內容摘要：本講次的講師林家和先生是本校電工系59級學長，本校傑出校友，也是一位優秀的企業家。退休以後。他選擇投入慈濟慈善事業基金會，他認為慈濟是一個成功的慈善「企業」，慈濟的理念與許多成功企業的經營理念不謀而合。內容：影音實況影音(*.flv檔)
Superparamagnetism Found in Diluted Magnetic Semiconductor Nanowires: Mn-Doped CdSe
(2008-11-20)
Chen, Chih-Chang
;
Hsu, Yung-Jung
;
Lin, Yi-Feng
;
Lu, Shih-Yuan
;
材料科學與工程學系
Diluted magnetic semiconductor (DMS) nanowires (NWs), Mn-doped CdSe, were successfully prepared in a gold-catalyzed vapor-transport deposition process. It was demonstrated for the first time that upon incorporation of Mn of very limited concentrations, the CdSe NWs exhibited enhanced ferromagnetism at T < 40 K and turned superparamagnetic at relatively high temperatures. This finding would extend the application range of DMS NWs into the biolabeling and bioimaging fields.
交大e-News第037期
(2008-11-20)
Secretariat
;
國立交通大學秘書室
本期摘要
(國立陽明大學, 2008-11-21)
陽明電子報編輯小組
天氣漸漸涼囉！神農坡上的學子正忙碌的準備著期中考試！本期電子報為您報導本校參加蒙古教育展的過程與本校國際志工團，勇闖內地廣西雲南愛之邊境的相關報導。想知道更多的陽明消息嗎？請參閱本期的電子報。陽明電子報編輯小組敬啟
2008「樂」活陽明表演藝術節第五場：啟彬與凱雅爵士四重奏
(國立陽明大學, 2008-11-21)
秘書室
2008「樂」活陽明表演藝術節第五場演出團體：啟彬與凱雅爵士四重奏 12月1日，星期一，晚間7：00 學生活動中心表演廳歡迎全校師生、教職員踴躍索票索票地點：人文與社會教育中心辦公室 312 索票日期：11月17日起開始索票相關網址：（點入本網址後，請點選「表演藝術與演講訊息」） http://www.ym.edu.tw/~lmlin/1280x800-Thursday/index00.htm ＊註：第四場西非部落索票至11月19日，禮拜三下班止。來不及索票者請在演出當晚直接至演出現場索票入場 2008「樂」活陽明表演藝術節第五場：終於來到了藝術節的壓軸節目─啟彬與凱雅爵士四重奏！！誰說聽爵士樂一定得在夏日夜晚？在帶著蕭瑟秋意的晚上傾聽搖擺的爵士樂亦別有一番風情。啟彬與凱雅夫妻檔在國內推廣爵士不遺餘力，亦多次應邀到陽明大學演講，深受好評。給自己一個理由來聽爵士樂吧！若找不到任何理由還是來聽吧─誰說聽音樂一定要說出什麼道理！一場成功的表演，除了台上演出者全神的投入外，觀眾也是關鍵之一，而且是最重要的關鍵。表演藝術看重的是台上與台下的互動。沒有觀眾的共鳴再精湛的演出亦是枉然。謝謝大家對此次2008「樂」活陽明表演藝術節的支持、推廣、與參與。＊註：表演廳共有205個座位承辦人：人文與社會教育中心助理教授林伶美單位：人文與社會教育中心電話：7364