Browsing by Author "Lin, YF"

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Adsorption and decomposition studies of t-butylamine, diethylamine, and methylethylamine on Si(100)-(2 x 1)
(2004-02-05)
Wu, JB
;
Yang, YW
;
Lin, YF
;
Chiu, HT
;
應用化學系
We have studied chemisorption and thermal decomposition of tert-butylamine (TBA), diethylamine (DEA), and methylethylamine (MEA) on Si(100)-(2 x 1) with synchrotron-based X-ray photoelectron spectroscopy (XPS) and temperature programmed desorption (TPD). Adsorption at cryogenic temperature leads to molecularly intact chemisorption (dative-bonding via the nitrogen lone pair) and dissociative chemisorption via N-H scission, producing distinct N 1s peaks at binding energies of 401.1 and 398.2 eV, respectively. The corresponding change for C 1s core level is also significant, and a 0.9 eV shift toward lower binding energy is found for DEA, suggesting a high degree of charge redistribution between two adsorption configurations. Upon warming to room temperature, the adsorbed amines almost completely transform into dissociative chemisorbed forms. Thermal decomposition of TBA at elevated temperatures produces desorption species of isobutylene via gamma-H elimination, hydrogen cyanide, and H-2. In comparison, DEA and MEA decompose thermally to desorb imine via P-H elimination, ethylene via beta-H elimination, hydrogen cyanide, and H2. Eventually, silicon nitride and silicon carbide are formed. Distinct decomposition pathways lead to a C/N ratio variation among the products, with TBA yielding the lowest C/N ratio.
Alignment of liquid crystals by ion etched grooved glass surfaces
(2005-12-01)
Lin, YF
;
Tsou, MC
;
Pan, RP
;
電子物理學系
;
Department of Electrophysics
The alignment properies of the nematic liquid crystal (LC) 4'-n-pentyl-4-cyanobiphenyl (5CB) on glass substrates with parallel grooves are studied. The U-shaped grooves with a variety of depths and periods were prepared by the reactive ion etch method. Surface morphology of the grooved glass was, examined by an Atomic Force Microscope. An LC cell consisting of a pair of parallel grooved substrates with 5CB sandwiched in between was assembled. The alignment quality for the LC was studied by measuring its surface azimuthal anchoring strength. The effect of the groove period and depth were studied. Strong anchoring with strengths larger than 10(-5) j/m(2) can be achieved with groove depths of 56 or 121 nm and periods less than 4 mu m.
Auto-tuning control of self-commissioning electric drives
(1997)
Tzou, YY
;
Lin, YF
;
電控工程研究所
;
Institute of Electrical and Control Engineering
This paper proposed a new ante-tuning self-commissioning (ATSC) control scheme for the positioning control of a dc drive for general-purpose servo applications. The ATSC controller consists of three major parts: a basic servo controller (BSC), an auto-tuning controller (ATC), and a self-commissioning controller (SCC). The proposed ATC is a generalized two-degree-of-freedom auto-tuning controller, it can be used to tune any two parameters of a controller without knowing its detailed control algorithm. The proposed ATSC control scheme has been applied to a dc drive for verification, Simulation and experimental studies of the ATSC dc drive have also been given.
Correlation between N 1s XPS binding energy and bond distance in metal amido, imido, and nitrido complexes
(2003-07-28)
Wu, JB
;
Lin, YF
;
Wang, JL
;
Chang, PJ
;
Tasi, CP
Synchrotron-based X-ray photoelectron spectroscopy is used to measure N 1s binding energies of several metal amido, imido, and nitrido complexes of group 5 and 6 metals. The N 1s binding energy decreases as the formal M-N bond order increases. A simple correlation between the contraction of the M-N bond and the lowering of binding energy is also observed. This correlation supports a notion that the bonding character of a linear metal-imido linkage resembles that of a metal-nitrido linkage closely.
Dual DSP based fully digital control of an AC induction motor
(1996)
Tzou, YY
;
Tsai, MF
;
Lin, YF
;
Wu, H
;
電控工程研究所
Intracavity measurement of liquid crystal layer thickness by wavelength tuning of an external cavity laser diode
(2005-10-03)
Lan, YP
;
Lin, YF
;
Li, YT
;
Pan, RP
;
Lee, CK
The gap of a planar-aligned liquid crystal (LC) cell is measured by a novel method: Monitoring the change in output wavelength of an external-cavity diode laser by varying the voltage driving the LC cell placed in the laser cavity. This method is particularly suitable for measurement of LC cells of small phase retardation. Measurement errors of +/- 0.5 % and +/- 0.6 % for 9.6-mu m and 4.25-mu m cells with phase retardations of 1.63 mu m and 0.20 mu m respectively are demonstrated. (c) 2005 Optical Society of America.
Liquid-crystal-based terahertz tunable Lyot filter
(2006-03-06)
Chen, CY
;
Pan, CL
;
Hsieh, CF
;
Lin, YF
;
Pan, RP
A two-element tunable Lyot filter operating in the terahertz (THz) frequency range is demonstrated. The central bandpass frequency of the filter can be continuously tuned from 0.388 to 0.564 THz (a fractional tuning range of 40%) using magnetically controlled birefringence in nematic liquid crystals. The transmission bandwidth is 0.1 THz and the insertion loss of the present device is 8 dB due to the scattering of LC molecules in the thick LC cells. This filter can be operated at room temperature. (c) 2006 American Institute of Physics.
Magnetically tunable room-temperature 2 pi liquid crystal terahertz phase shifter
(2004-06-14)
Chen, CY
;
Hsieh, CF
;
Lin, YF
;
Pan, RP
;
Pan, CL
Tunable phase shift up to 360degrees at 1 THz is achieved with a liquid crystal (LC) device. The key to this design is (1) the use of a nematic LC, E7, which exhibits a birefringence of similar to0.17 (0.2-1.2 THz); (2) a LC cell (3-mm in thickness) with sandwiched structure to increase the interaction length while minimizing interface Fresnel losses; and (3) the use of magnetic field to align the thick LC cell and achieve continuous tuning of phase from 0 to 360degrees. This device can be operated over a broad range near room temperature. (C) 2004 Optical Society of America.
Single-longitudinal-mode semiconductor laser with digital and mode-hop-free fine-tuning mechanisms
(2004-12-27)
Shih, TS
;
Lan, YP
;
Lin, YF
;
Pan, RP
;
Pan, CL
We report a novel external cavity laser diode (lambda = 1.5 mum). An intra-cavity liquid crystal pixel mirror allows digitally tuning of the laser wavelength to more than 40 wavelength channels of 100 GHz spacing according to the International Telecommunication Union (ITU) grid. Laser wavelength can further be fine-tuned by varying the driving voltages applied to an intra-cavity planar nematic liquid crystal phase plate. With a cell 52.3 mum in thickness, the output frequency can be continuously tuned over 1.89 GHz. The root-mean-square voltage required for driving the phase plate was from 1.00 to 4.56 volts. (C) 2004 Optical Society of America.
Surface reaction of bis(tertbutylimido)bis(diethylamido)tungsten precursor on Si(100)-(2X1)
(2003-09-01)
Wu, JB
;
Yang, YW
;
Lin, YF
;
Chiu, HT
;
應用化學系
Thermal decomposition of a metal-organic chemical vapor deposition precursor, (t-BuN=)(2)W(-NEt2)(2), (bis(tertbutylimido)bis(diethylamido)tungsten, on Si(100) has been studied by means of synchrotron radiation-based x-ray photoemission spectroscopy and temperature programmed desorption spectroscopy. The, resultant thin films consist of tungsten metal, silicon carbides and silicon nitrides. Major desorption products, originated from ligand decomposition include imine (C2H5N=CHCH3) that is derived from beta-H elimination of diethylamido ligand, and isobutene (C4H8) that is generated from gamma-H elimination of t-butylimido ligands. The. transmetalation of the precursor leads to tungsten metal adsorption on Si(100); by contrast, tungsten nitrides, tungsten carbides and tungsten oxides are produced as the same precursor is decomposed on SiO2 surface. (C) 2003 American Vacuum Society.
Surface topography and alignment effects in UV-modified polyimide films with micron size patterns
(2003-04-01)
Pan, RP
;
Chiu, HY
;
Lin, YF
;
Huang, JY
;
電子物理學系
The characteristics of UV-modified polyimide CBDA-BAPP films for liquid crystal (LC) alignment have been investigated. Linearly polarized ultra-violet laser light (lambda = 325 nm) was used to expose the film. The LC direction of this film tends to be oriented parallel to the surface and perpendicular to the polarization direction of the laser light. The uniformity of the LC direction stabilizes when the exposure time exceeds a certain length. From the atomic force microscope investigation, we find that the films have been dented at the places exposed to the laser light. When a mask with striped pattern was used during exposure, we observed grooves in the exposed regions. The grooved patterns agree well with the calculated diffraction patterns caused by the mask, however, the groove direction has no effect on the alignment of the LCs. In our experiments, we also achieved LC alignment patterns as small as 2 mum using UV exposure with a mask.
Temperature dependence of azimuthal anchoring strength of liquid crystals on microgrooved glass substrate
(2005-12-01)
Lin, YF
;
Lu, SY
;
Pan, RP
;
電子物理學系
;
Department of Electrophysics
The temperature dependence of the azimuthal anchoring strength of the nematic liquid crystal (LC) 4'-n-pentyl-4cyanobiphenyl (5CB) on parallel grooved glass substrates has been studied. The U-shaped grooves are prepared by reactive ion etching. Two parallel grooved substrates with chiral doped 5CB sandwiched in between are used to form an LC cell. The azimuthal anchoring strength in the nematic temperature range is determined by measuring the twist angle in the LC cells using an optical method at two laser wavelengths. The anchoring strength decreases steadily with increasing temperature. The change in the anchoring strength is attributed to-the change in the elastic constant K(22) unless the temperature is close to the clearing point.
Thermal decomposition mechanisms of tungsten nitride CVD precursors on Cu(111)
(2006-02-01)
Yang, YW
;
Wu, JB
;
Wang, JL
;
Lin, YF
;
Chiu, HT
Chemisorption and thermal decomposition of metallorganic chemical vapor deposition precursors, (t-BuN)(2)W(NHBu-t)(2), bis(tertbutyl imido) bis(tert-butylamido) tungsten (BTBTT) and (t-BuN)(2)W(NEt2)(2), bis(tert-butylimido)bis(diethylamido)tungsten (BTBDT), on Cu(111) have been investigated by means of thermal desorption spectroscopy (TDS) and synchrotron-based X-ray photoelectron spectroscopy (SR-XPS) under ultrahigh vacuum conditions. The precursors remain intact upon chemisorption on Cu(111) at 100 K, and at 300 K both precursors decompose readily via the characteristic hydride abstraction/elimination pathways to produce two stable surface intermediates for each precursor. For BTBTT, one species is W(=NBu-t)(3) and the other is proposed to be a bridged amido complex, [(t-BuN)(2)W(mu-NBu-t)](2). In comparison, a W-imine complex and a W-N-C metallacycle are two intermediates produced from BTBDT, Annealing toward 800 K further decomposes the intermediates and the detectable desorption species are completely derived from the ligands. The desorption products from BTBTT include t-butylamine generated from alpha-H abstraction, isobutylene from gamma-H elimination, acetonitrile from beta-methyl elimination.. and molecular hydrogen. In addition to these desorption species, BTBDT produces hydrogen cyanide and imine (EtN = CHMe) via beta-H elimination, not possible with BTBTT due to the absence of beta-H in the ligands. Eventually, tungsten nitrides incorporating oxygen atoms and a small amount of graphitic carbons are formed and the stoichiometry is approximated as WN1.5O0.1. Oxygen incorporation, driven by a large oxide formation enthalpy, is sensitively dependent on the moisture exposure in UHV environment. (c) 2005 Elsevier B.V. All rights reserved.
Using mobile agent and SOAP-RPC in an advanced traveler information system
(2003)
Lu, KS
;
Lin, YF
;
Chen, JJY
;
資訊工程學系
;
Department of Computer Science
This paper presents a scheme to combine two existing techniques, mobile agent and SOAP-RPC, in. an advanced traveler information system. This architecture consists of three logical layers: 1) mobile agent, 2) local service, and 3) remote service. The advanced traveler information system uses the techniques of: 1) IBM Aglet mobile agent and 2) simple object access protocol (SOAP). Its advantages appear to be: 1) by migrating to wired network for local service, the mobile agent overcomes the barrier of insufficient bandwidth in wireless network, and 2) SOAP greatly facilitates accessing remote services in heterogeneous web environment.
Using mobile-agent and SOAP-RPC in an advanced traveler information system
(2003)
Lu, KS
;
Lin, YF
;
Chen, JJY
;
交大名義發表
;
National Chiao Tung University
This paper presents' a scheme to combine two existing techniques, mobile agent and SOAP-RPC, in an advanced traveler information system. This architecture consists of three logical layers: 1) mobile agent, 2) local service, and 3) remote service. The advanced traveler information system uses the techniques of: 1) IBM Agletmobile agent and 2) simple object access protocol (SOAP). Its advantages appear to be: 1) by migrating to wired network. for local service, the mobile agent overcomes the barrier of insufficient bandwidth in wireless network, and, 2) SOAP greatly, facilitates. accessing remote services in heterogeneous web environment.