Browsing by Issue Date, starting with "2004-11-05"

Now showing 1 - 20 of 69188

Investigation of the thermal properties of novel adamantane-modified polybenzoxazine
(2004-11-05)
Su, YC
;
Chen, WC
;
Chang, FC
;
應用化學系
;
Department of Applied Chemistry
Two novel structures of adamantane-modified benzoxazines were synthesized from 4-(1-adamantyl)-phenol through the incorporation of adamantane as a pendant group into the polybenzoxazine backbone. Both H-1-NMR and Fourier transform infrared spectra were used to characterize these structures. The rigid structure of the adamantane tended to hinder the chain mobility (boat anchor effect) and substantially enhanced the thermal properties, including the glass-transition temperature and decomposition temperature, especially for poly(6-adamantyl-3-methyl-3,4-dihydro-2H-1,3-benzoxazine). In the poly(6-adamantyl-3-phenyl-3,4-dihydro-2H-1,3-benzoxazine) system, however, the opposite result for the glass-transition temperature was observed and it was interpreted as lower crosslinking density. The phenyl group was bulkier than the methyl group, and the movement of the molecular chain was hindered between bridging points during the curing process; this resulted in a lower crosslinking density and a lower glass-transition temperature than those of poly(6-adamantyl-3-methyl-3,4-dihydro-2H-1,3-benzoxazine). (C) 2004 Wiley Periodicals, Inc.
A fully integrated 5.2-GHz single-ended-in and single-ended-out 0.18-mu m CMOS Gilbert upconverter
(2004-11-05)
Meng, CC
;
Lin, MQ
;
Huang, GW
;
電信工程研究所
;
Institute of Communications Engineering
A monolithic 5.2-GHz single-ended-in and single-ended-out Gilbert upconverter with balanced operation is demonstrated using 0.18-mum deep n-well CMOS technology. Thefully matched Gilbert upconverter has conversion gain of - 11.5 dB and OPIdB of - 19 dBm when input IF = 300 MHz, LO = 4.9 GHz, and output RF = 5.2 GHz. The IF input return loss is better than 14 dB for frequencies up to 7 GHz, while RF output return loss is 15 dB at 5.2 GHz. (C) 2004 Wiley Periodicals, Inc.
Highly efficient yellow and white organic electroluminescent devices doped with 2,8-di(t-butyl)-5,11-di[4-(t-butyl)phenyl]-6,12-diphenylnaphthacene
(2004-11-08)
Liu, TH
;
Wu, YS
;
Lee, MT
;
Chen, HH
;
Liao, CH
We describe the applications of a sterically-hindered yellow dopant, 2,8-di(t-butyl)-5,11-di[4-(t-butyl)phenyl]-6,12-diphenylnaphthacene (TBRb) which, when compared to 5,6,11,12-tetraphenylnaphthacene (Rb) in either tris(8-hydroxyquinolinato)aluminum or 1,4-bis[N-(1-naphthyl)-N-'-phenylamino]-4,4(') diamine (NPB) as host emitter, shows a 50%-34% increase in luminance efficiency over that of Rb device without significantly affecting its color. In addition, we have incorporated the TBRb doped yellow NPB emitter into the two-element white organic light-emitting diodes based on p-bis(p-N,N-di-phenyl-aminostyryl)benzene doped 2-methyl-9,10-di(2-naphthyl) anthracene sky-blue emitter which improved the luminance efficiency by 44% over that of Rb to 12.8 cd/A and 4.3 lm/W at 20 mA/cm(2) with CIEx,y=[0.31,0.38]. (C) 2004 American Institute of Physics.
Molecular elimination in photolysis of fluorobenzene at 193 nm: Internal energy of HF determined with time-resolved Fourier-transform spectroscopy
(2004-11-08)
Wu, CY
;
Wu, YJ
;
Lee, YP
;
應用化學系
;
Department of Applied Chemistry
Following photodissociation of fluorobenzene (C6H5F) at 193 nm, rotationally resolved emission spectra of HF(1less than or equal toupsilonless than or equal to4) in the spectral region 2800-4000 cm-1 are detected with a step-scan Fourier-transform spectrometer. In the period 0.1-1.1 mus after photolysis, HF(upsilonless than or equal to4) shows similar Boltzmann-type rotational distributions corresponding to a temperature similar to1830 K; a short extrapolation from data in the period 0.1-4.1 mus leads to a nascent rotational temperature of 1920+/-140 K with an average rotational energy of 15+/-3 kJ mol(-1). The observed vibrational distribution of (upsilon = 1):(upsilon = 2):(upsilon = 3):(upsilon = 4)=(60+/-7):(24+/-3):(10.5+/-1.2):(5.3+/-0.5) corresponds to a vibrational temperature of 6400+/-180 K. An average vibrational energy of 33+/-9/3 kJ mol(-1) is derived based on the observed population of HF(1less than or equal toupsilonless than or equal to4) and an estimate of the population of HF(upsilon=0) by extrapolation. The observed internal energy distribution of HF is consistent with that expected for the four-center (alpha,beta) elimination channel. A modified impulse model taking into account geometries and displacement vectors of transition states during bond breaking predicts satisfactorily the rotational excitation of HF. We also compare internal energies of HF observed in this work with those from photolysis of vinyl fluoride (CH2CHF) and 2-chloro-1,1-difluoroethene (CF2CHCl) at 193 nm. (C) 2004 American Institute of Physics.
Bottle beam from a bare laser for single-beam trapping
(2004-11-10)
Chen, CH
;
Tai, PT
;
Hsieh, WF
;
光電工程學系
;
Department of Photonics
We demonstrate that a laser beam converging from a specific transverse mode is a bottle beam, as described in J. Opt. Soc. Am. B 20, 1220 (2003). To our knowledge, this is the first time that a bottle beam has been generated directly from a laser. By calculating the radiation forces on a dielectric Rayleigh sphere in the bottle beam, we show that the single beam can trap high-refractive-index particles at the multiple axial sites of intensity maxima, and it can confine low-index particles on a transverse plane within the bottle regions. Such a novel laser beam may have other applications. (C) 2004 Optical Society of America.
Orientations of two coupled molecules
(2004-11-11)
Liao, YY
;
Chen, YN
;
Chuu, DS
;
電子物理學系
;
Department of Electrophysics
Orientation states of two coupled polar molecules controlled by laser pulses are studied theoretically. By varying the period of a series of periodically applied laser pulse, transition from regular to chaotic behavior may occur. Schmidt decomposition is used to measure the degree of entanglement. It is found that the entanglement can be enhanced by increasing the strength of laser pulse. (C) 2004 Elsevier B.V. All rights reserved.
用於資料儲存裝置的飛行讀寫頭構造
(2004-11-11)
呂宗熙
;
劉柏清
;
余興政
本發明一種用於資料儲存裝置的飛行讀寫頭構造，其係由一線圈部、一樞軸及一懸臂所構成，其中，該懸臂之一端係設置有一壓電彎片，該壓電彎片係以雙層或多層之壓電材料所製成，藉著導線通以適當之電壓及電流，使壓電彎片可同時產生橫向彎曲及縱向伸縮；並於該壓電彎片之一端裝設有一讀寫頭；如是，可藉由壓電彎片，達到一併執行對焦和尋軌兩個方向之微調，且由於壓電彎片類似雙金屬(bimetal) 元件的特性，而能夠在橫向呈現大幅的彎曲，以供補償轉動中光碟片的大幅變形，使得讀寫頭在控制機制下，將飛行高度維持於焦距範圍內俾使讀寫頭順利讀寫。
Behavior and surface energies of polybenzoxazines formed by polymerization with argon, oxygen, and hydrogen plasmas
(2004-11-15)
Chen, JK
;
Lin, IK
;
Ko, FH
;
Huang, CF
;
Chen, KS
Polybenzoxazine (PBZZ) thin films can be fabricated by the plasma-polymerization technique with, as the energy source, plasmas of argon oxygen or hydrogen atoms and ions. When benzoxazine (BZZ) films are polymerized through the use of high-energy argon atoms, electronegative oxygen atoms, or excited hydrogen atoms, the PBZZ films that form possess different properties aid morphologies in their surfaces. High-energy argon atoms provide a thermodynamic factor to initiate the ring-opening polymerization of BZZ and result in the polymer surface having a grid-like structure. The ring-opening polymerization of the BZZ film that is initiated by cationic species such as oxygen atoms in plasma, is propagated around nodule structures to form the PBZZ. The excited hydrogen atom plasma initiates both polymerization and decomposition reactions simultaneously in the BZZ film and Results in the formation of a porous structure on the PBZZ surface. We evaluated the surface energies of the PBZZ films polymerized by the action of these three plasmas by measuring the contact angles of diiodomethane and water droplets. The surface roughness of the films range from 0.5 to 26 nm, depending on the type of carrier gas and the plasma-polymerization time. By estimating changes in thickness, we found that tie PBZZ film synthesized by the oxygen plasma-polymerization process undergoes the slowest rate of etching in CF(4) plasma. (C) 2004 Wiley Periodicals, Inc.
Improvement of kink characteristics performance of GaAsVCSEL with a indium-tin-oxide top transparent overcoating
(2004-11-15)
Lai, F
;
Chang, YH
;
Hsueh, TH
;
Huang, HW
;
Laih, LH
We demonstrated the enhancement in the performance of proton-implanted GaAs VCSEL by incorporation of a new p-contact scheme using a Ti and ITO transparent overcoating on the regular p-contact. The kink characteristics in light output power versus current (L-I) curve of the VCSEL with the Ti/ITO overcoating were improved with a reduction in the derivative kink factor of as large as 70%. The high-speed response of the overcoated device also shows a more open clear eye and lower jitter of 35 ps operating at 2.125 Gb/s under 10 mA bias and 9 dB extinction ratio compared to the no overcoated device. Better current spreading and uniformity induced by the overcoating could be responsible for these performance improvements. (C) 2004 Elsevier B.V. All rights reserved.
Physical characteristics and photoluminescence properties of phosphorous-implanted ZnO thin films
(2004-11-15)
Lin, CC
;
Chen, SY
;
Cheng, SY
;
材料科學與工程學系
;
Department of Materials Science and Engineering
ZnO films were implanted with phosphorus in the range from 5 x 10(12) to 5 x 10(15) cm(-2). Effect of phosphorus concentration on structural characteristics and photoelectric behavior of phosphorus-implanted ZnO films under different atmosphere and annealing treatment was investigated. It has been demonstrated that below solubility (1.5 x 10(18) ions/cm(3)), the defect formation will be dominated by annealing atmosphere and more defects can be formed in oxygen ambient than in nitrogen atmosphere as revealed from PL spectra. However, excess phosphorus doping, above solubility (1.5 x 10(18) ions/cm(3)), will induce the formation of the phosphide compounds in ZnO films and seriously deteriorate the crystallinity and optical property of the films. However, a high-resistive but not p-type ZnO film is obtained by phosphorus doping. (C) 2004 Elsevier B.V. All rights reserved.
Electron inelastic mean free paths and surface excitation parameters for GaAs
(2004-11-15)
Kwei, CM
;
Li, YC
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Surface excitation parameters and inelastic mean free paths of electrons are of importance in the analyses of surface sensitive electron spectroscopies. When probe electrons are near the surface of a solid or the interface of an overlayer system, electron inelastic mean free paths become depth-dependent. These mean free paths and surface excitation parameters were calculated for electrons crossing the surface of GaAs. Calculations were performed for both incident and outgoing electrons by the use of a dielectric response theory. Applications were made to estimate the elastic backscattering intensity of electrons at different emission angles using the Monte Carlo simulations. Good agreement was found between calculated results and experimental data on the ratio of the elastic reflection coefficient for a GaAs sample relative to a Ni reference. Such a ratio was used to determine the effective electron inelastic mean free paths in GaAs by employing the surface excitation parameter obtained from Monte Carlo simulations. (C) 2004 Elsevier B.V. All rights reserved.
Efficient white light emission in conjugated polymer homojunctions
(2004-11-15)
Ho, GK
;
Meng, HF
;
Lin, SC
;
Horng, SF
;
Hsu, CS
We study polymer light-emitting diodes with a homojunction, i.e., junction between two layers with the same host material. One layer is poly (9,9-dioctylfluorene-2,7-diyl) (PFO) host blended with a small amount of poly (2-methoxy-5 (2'-ethyl-hexyloxy)-1,4-phenylene vinylene), another layer is either pure PFO or PFO host blended with green-emitting polyfluorene copolymers. Such homojunction devices are solution processed and show efficient white light emission. The peak luminance 3000 cd/m(2) is reached at 10 V with Internationale de L'Eclairage (CIE) coordinate (0.34, 0.34). (C) 2004 American Institute of Physics.
Electrical resistivities and thermopowers of transparent Sn-doped indium oxide films
(2004-11-15)
Li, ZQ
;
Lin, JJ
;
電子物理學系
;
物理研究所
;
Department of Electrophysics
We have systematically measured the electrical resistivities and thermopowers of transparent tin-doped indium oxide films. We found that the resistivities obey the Bloch-Gruneisen law between 25 and 300 K, whereas below 25 K, the resistivities slightly increase logarithmically with the decreasing temperature due to the weak-localization and electron-electron interaction effects. The thermopowers are negative and decrease linearly with temperature from 300 K down to 1.8 K. Our results strongly indicate that the tin-doped indium oxide films behave as a good, free-electron-like conductor while being transparent. (C) 2004 American Institute of Physics.
Efficient 1521-nm Nd : GdVO4 Raman laser
(2004-11-15)
Chen, YF
;
電子物理學系
;
Department of Electrophysics
An efficient compact diode-pumped actively Q-switched Nd:GdVO4 laser at 1521 nm is demonstrated by use of the nonlinear optical process of stimulated Raman scattering. With a 13.6-W diode pump power, greater than 1.18 W of 1521-nm average power at a repetition rate of 20 kHz is generated. At a repetition rate of 5 kHz, the pulse width is shorter than 5 ns and the peak power is higher than 20 kW. (C) 2004 Optical Society of America.
Low voltage lead titanate/Si one-transistor ferroelectric memory with good device characteristics
(2004-11-15)
Sun, CL
;
Chen, SY
;
Liao, CC
;
Chin, A
;
材料科學與工程學系
We have developed one-transistor ferroelectric memory using lead titanate (PTO) as a gate dielectric directly formed on Si without any buffer layer. The PTO/Si metal-oxide-semiconductor field-effect transistor memory has shown a large threshold voltage shift of 1.6 V at only +/-4 V program/erase voltages. The corresponding good interface was achieved by lowering the anneal temperature to 450 degreesC. Besides the sharp capacitance change of 0.17 muF/V cm(2), it was also evidenced by the high mobility of 169 cm(2)/V s close to high-kappa HfO2. In addition, long retention >1000 s and endurance >10(11) stress cycles in the device suggested good memory characteristics. (C) 2004 American Institute of Physics.
Interfacial microstructure and electrical properties of PT/Al2O3/Si annealed at high temperatures
(2004-11-15)
Chen, SY
;
Hsiao, CS
;
Hsu, JJ
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Pb1+xTiO3 (PT) thin films were deposited on Al2O3(10 nm)/Si using lead acetate trihydrate and titanium isopropoxide with the addition of glycerol (GL) chelating agent as precursors. It was found that perovskite PT phase can be well crystallized at a lower temperature of 600 degreesC and excellent memory properties are obtained. However, with increasing annealing temperature above 700 degreesC, charge-injection mode instead of ferroelectric behavior was detected. Cross-sectional TEM results illustrate that with an increase of annealing temperature and Pb content in the PT films, diffusion envelops and even composition separations were detected in the interface of PT/Al2O3/Si. It was believed that the degradation in the ferroelectric memory properties is strongly related to the change of microstructure and composition in the interface of PT/Al2O3/Si. (C) 2004 Elsevier B.V. All rights reserved.
White organic light-emitting diodes based on 2,7-bis(2,2-diphenylvinyl)-9,9 '-spirobifluorene: Improvement in operational lifetime
(2004-11-15)
Chuen, CH
;
Tao, YT
;
Wu, FI
;
Shu, CF
;
應用化學系
Very bright white organic light-emitting diodes were fabricated using 2,7-bis(2,2-diphenylvinyl)-9,9(')-spirobifluorene (DPVSBF) doped with [4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran)] (DCJTB) as the emission layer. With a device configuration of ITO/NPB(40 nm)/DPVSBF:0.2%DCJTB(11 nm)/Alq(30 nm)/LiF(1 nm)/Al(150 nm), a brightness of 1575 cd/m(2) with an external quantum efficiency of 3.31% and luminous efficiency of 8.00 cd/A, a power efficiency of 5.35 lm/W was achieved at a driving current of 20 mA/cm(2) (4.7 V). The brightness reached 66 000 cd/m(2) at 15 V. The Commission Internationale de l'Eclairage coordinates stayed nearly constant, changed from (0.35, 0.36) to (0.32, 0.34) when the voltage increased from 6 to 12 V. The relative operational lifetime of the device increased by a factor of similar to20 compared with a similar device based on 4,4(')-bis-(2,2-diphenylvinyl)-1,1(')-biphenyl as the source of the blue emission. The much extended half-lifetime was attributed to the higher morphological stability of the DPVSBF. (C) 2004 American Institute of Physics.
施工公告
(國立陽明大學, 2004-11-16)
陽明電子報編輯小組
本校「致和新村二期景觀工程」於即日起開始施工，預定十二月二日前完成，請注意安全並有任何問題請電本校營繕組，施工期間造成不便，請多多包涵。
工研院國防訓儲徵才說明會
(國立陽明大學, 2004-11-16)
陽明電子報編輯小組
時間：93年11月19日（五）10：00 ~ 12：00 地點：學生活動中心第一會議室活動行程： 10：00- 10：10 致詞 10：10- 10：40 工研院概況介紹與徵才作業介紹 10：40- 12：00 前瞻技術研發經驗分享（生醫領域）
九十三學年度第一學期醫學系網路教學評鑑
(國立陽明大學, 2004-11-16)
陽明電子報編輯小組
教師教學意見調查活動時間：93/10/4 至 94/1/19 活動對象：醫學系一至五年級同學問卷放置處：「校務行政系統」→「教學評鑑」→「教師教學意見調查」