Browsing by Issue Date, starting with "1992-08-01"

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FLUX MOTION DEPENDENCE OF RESISTIVE PROPERTIES IN SUPERCONDUCTING YBA2CU3O7-X THIN-FILMS
(1992-08-01)
HAUNG, CJ
;
CHEN, YC
;
TSENG, TY
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Two models of flux motion are employed to study the resistive properties of superconducting YBa2Cu3O7-x thin films. The thermally activated flux creep model is employed to explain the dissipative behavior in the low resistivity region. However, when the resistivity is raised and approaches the normal state resistivity, the dissipative mechanism is gradually transferred from flux creep to flux flow. Based on the flux flow model, the upper critical field is estimated and shown as a function of temperature. In addition, a parallel resistivity circuit model is proposed to describe the transition behavior of the magnetic field dependence of resistivity versus current density characteristics.
DEPOSITION OF SILICON-CARBIDE THIN-FILMS FROM 1,1-DIMETHYL-1-SILACYCLOBUTANE
(1992-08-01)
CHIU, HT
;
LEE, SF
;
交大名義發表
;
應用化學系
;
National Chiao Tung University
1,1-Dimethyl-1-silacyclobutane was used as a single-source precursor to deposit SiC thin films on Si(100) and Si(111) by low-pressure chemical vapor deposition (LPCVD). Polycrystalline beta-SiC thin films were grown at temperatures 1100 and 1200-degrees-C. At temperatures between 950 and 1100-degrees-C, amorphous thin films of silicon carbide were obtained. The films were studied by X-ray diffraction (XRD), infrared spectroscopy (IR), scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), and electron diffraction (ED).
FRANZ-KELDYSH OSCILLATIONS OF DELTA-DOPED GAAS
(1992-08-01)
HSU, TM
;
TIEN, YC
;
LU, NH
;
TSAI, SP
;
LIU, DG
Si-delta-doped GaAs (N2D almost-equal-to 10(11) cm-2) samples grown by molecular-beam epitaxy are investigated by using photoreflectance spectroscopy. The oscillations observed above the GaAs fundamental band gap are attributed to the Franz-Keldysh effect in the region between the delta-doped layer and the crystal surface. This ascription is confirmed by detailed studies through varying the cap thickness (250-2500 angstrom), temperature (10-450 K), and laser pump power (0.05-7 mW/cm2). The surface potential deduced from the Franz-Keldysh oscillations is found to be temperature and laser pump power dependent, which is explained by taking the surface photovoltaic effect into account. The surface Fermi level has been measured by this method and is found to have the value 0.73+/-0.02 V.
NONLINEAR TE-WAVE PROPAGATION IN A SYMMETRICAL, CONVERGING, SINGLE-MODE Y-JUNCTION WAVE-GUIDE
(1992-08-01)
SHI, TT
;
CHI, S
;
光電工程學系
;
電信研究中心
;
Department of Photonics
Nonlinear TE-wave propagation in a symmetric, converging, single-mode Y-junction waveguide is investigated. Numerical results simulated by the beam-propagation method showed that the insertion loss depends on the power of the incident light and can be reduced to 0.89 dB for some appropriate power. The insertion loss can be further decreased, but the wave propagating in the stem begins to oscillate.
A QUANTITATIVE STUDY OF THE FAR-FIELD LASER-INDUCED RING PATTERN FROM NEMATIC LIQUID-CRYSTAL FILMS
(1992-08-01)
PAN, RP
;
CHEN, SM
;
PAN, CL
;
電子物理學系
;
光電工程學系
We report the first detailed measurement of multiple (up to twenty) diffraction rings due to a laser beam traversing a nematic liquid crystal cell. Experimental measured intensity distributions are in good agreements with numerical calculations based on the diffraction theory, taking into account the spatial self-phase modulation effect, the two-dimensionality of the problem, the wavefront curvature effect and the non-local response of the nematic liquid crystals. The individual contributions of the aforementioned effects on the far-field pattern are clearly illustrated.
USING INFORMATION TECHNOLOGY FOR SUCCESSFUL DOCUMENT MANAGEMENT-SYSTEMS
(1992-08-01)
LIU, HY
;
TARNG, MY
;
交大名義發表
;
管理科學系
;
National Chiao Tung University
THE SCALING BEHAVIORS OF PINNING IN TLBACACUO SUPERCONDUCTING THIN-FILMS
(1992-08-01)
CHANG, HL
;
WANG, C
;
JUANG, JY
;
UEN, TM
;
GOU, YS
The scaling behaviors of global pinning force density in dc sputtered TlBaCaCuO superconducting thin films as functions of both reduced magnetic fields and temperatures were investigated by direct transport measurements with applied fields perpendicular to the film surface. The pinning mechanisms which were depicted by the scaling behaviors of the Tl-based thin films were found to be strongly dependent on the superconducting properties of the films. For films with high critical current densities the conventional flux line shear pinning appeared to be the predominant limiting mechanism for the current carrying capability. Whereas in more granular film that did not scale well when normalized by the extrapolated Hc2, an astonishing scaling behavior by taking a reversible field H* as the normalization parameters was observed.
POLY(DIMETHYL-CO-DIPHENYLSILANE) AS A DEEP-UV AND AN OXYGEN PLASMA PORTABLE CONFORMABLE MASK
(1992-08-01)
LOONG, WA
;
WANG, TH
;
交大名義發表
;
應用化學系
;
National Chiao Tung University
Bi-layer resist processes for deep-UV and oxygen plasma are studied. Poly(dimethyl-co-diphenylsilane) is used as both deep-UV and oxygen plasma portable conformable masks because of its strong deep-UV and i-line (365 nm) absorption and its resistance to oxygen plasma. The bottom layer is P(MMA-PhPK), a copolymer of methylmethacrylate and 30 wt% of phenylpropenylketone, for the positive-tone pattern. P(MMA-PhPK) has greater deep-UV exposure sensitivity compared to PMMA. Good vertical sidewall profiles of lines of bottom layers are obtained.
ON THE DESIGN OF VLSI ARRAYS FOR DISCRETE FOURIER-TRANSFORM
(1992-08-01)
LIU, CM
;
JEN, CW
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資訊工程學系
;
電子工程學系及電子研究所
;
Department of Computer Science
In this paper the design of VLSI arrays for discrete Fourier transform (DFT) is investigated through three topics: (i) algorithm exploitation, derivation and analysis, (ii) array realisation, and (iii) schemes to calculate arbitrarily long length DFT using a reasonable sized array. Four DFT systolic algorithms are examined and compared in terms of computing parallelism and computational complexity. Among the four algorithms, one is newly proposed. The new one exhibits much higher computing parallelism and lower computational complexity than the other three, but is applicable when the DFT length is prime. Based on the four algorithms, seven systolic arrays and seven two-level pipelined systolic arrays are devised. The outstanding features of these arrays are that the number of I/O channels is independent of the DFT length and the time overhead in manipulating consecutive data bundles are eliminated. Two schemes are presented to calculate long-length DFT using arrays with a reasonable number of processing elements. Performance of different algorithms, arrays and schemes is compared and summarised in six tables to serve as the selection criteria for different applications.
INVESTIGATION ON THE INTERFACE OF THE POLYCRYSTALLINE SILICON CONTACTED DIODE FORMED WITH A STACKED AMORPHOUS-SILICON FILM
(1992-08-01)
WU, SL
;
LEE, CL
;
LEI, TF
;
LEE, TL
;
CHEN, LJ
The structural morphology of the poly-single crystalline silicon interface of a diode formed with a stacked-amorphous-silicon (SAS) film has been investigated. Secondary ion mass spectroscopy analyses showed the existence of multi-dopant segregation peaks at each layer boundary and at the poly-single crystalline silicon interface. The break-up at the poly-single silicon interface and the epitaxial regrowth of the polysilicon realigned to the silicon substrate were found to depend not only on the polysilicon deposition and the post annealing conditions, but also on the number and the thickness of the stacked amorphous silicon layers. For the diode formed with a six-layer stacked amorphous silicon, break-up of the interface was found to occur even at an annealing temperature as low as 900-degrees-C. After an additional annealing at 1000-degrees-C for 20 min, the interface was fully broken-up and the epitaxial regrowth layer of the polysilicon could be as thick as 760 angstrom.
THE BINDING-ENERGY OF HYDROGENIC IMPURITIES IN QUANTUM-WELL STRUCTURES UNDER ELECTRIC-FIELDS
(1992-08-01)
HAN, CS
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HSIEH, YC
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交大名義發表
;
電子物理學系
;
National Chiao Tung University
The effect of an electric field on the hydrogenic impurity state in a quantum well is studied by using the variational-perturbative method. The variation of the binding energy as a function of the electric field with different well widths and impurity positions is calculated. We have also extended the calculation for the finite quantum well and some interesting points are discussed.
THE PROCESS WINDOW OF A-SI/TI BILAYER METALLIZATION FOR AN OXIDATION-RESISTANT AND SELF-ALIGNED TISI2 PROCESS
(1992-08-01)
LOU, YS
;
WU, CY
;
CHENG, HC
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
The dependences of both oxidation-resistant and self-aligned silicidation properties on the thicknesses of top amorphous-Si (a-Si) and Ti metal in an a-Si/Ti bilayer process are presented. It is shown that a thin silicide layer formed during the reaction between a-Si and Ti films becomes a stable oxidation and nitridation barrier for oxygen- and nitrogen-related impurities. Moreover, the formation sequence of the silicide phase depends on not only the annealing temperature but also the thickness of Ti film. In addition, the preferential orientation of the silicide phase after annealing at high temperature also shows a strong dependence of the thickness of Ti film, which is attributed to the difference of the grain size in the polycrystalline silicide film. The allowed process window for the a-Si thickness can be determined experimentally and a reproducible and homogeneous self-aligned TiSi2 film can be easily obtained by using the a-Si/Ti bilayer process in SALICIDE applications despite of high-level contaminations of oxygen impurities in both the as-deposited Ti film and the annealing ambient.
NUMERICAL-SIMULATION OF THE HYSTERESIS IN THE SIDEGATING EFFECT IN GAAS-MESFETS - THE EFFECT OF SCHOTTKY CONTACTS
(1992-08-01)
CHANG, SJ
;
LEE, CP
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Two-dimensional simulation of the sidegating effect in GaAs MESFET's has been performed. The result confirms that Schottky contacts on semi-insulating substrate cause serious high substrate leakage current and drain current reduction in GaAs MESFET's. The competition between the currents or biases of the contacts is found to be the cause of the S-type negative differential conductivity (S-NDC) or hysteresis observed when measuring the sidegating threshold.
OPTICALLY CLEAR SIMULTANEOUS INTERPENETRATING POLYMER NETWORKS BASED ON POLY(ETHYLENE GLYCOL) DIACRYLATE AND EPOXY .1. PREPARATION AND CHARACTERIZATION
(1992-08-01)
LIN, MS
;
JENG, KT
;
交大名義發表
;
應用化學系
;
National Chiao Tung University
Poly(ethylene glycol) diacrylate was synthesized from poly(ethylene glycol) of molecular weight 600 with acryloyl chloride in a molar ratio of 1 : 2. Poly (ethylene glycol) diacrylate (PEGDA) was then blended with diglycidyl ether of bisphenol A (DGEBA) in various ratios, followed by curing with 2,2'-azobisisobutyronitrile (AIBN) and isophronediamine (IPDA) simultaneously. Viscosity changes before and during IPN formation were examined with a Brookfield viscometer. Formation of H-bonding and functional group changes were investigated with FTIR. Exothermic curing thermograms were recorded with dynamic DSC. Optically clear IPNs thus obtained were characterized with rheometric dynamic spectroscopy (RDS) and scanning electron microscopy (SEM) to check possible compatibility of the two networks. Experimental results revealed that during IPN formation hydrogen bonds between PEGDA and DGEBA and interlock of networks had profound effect on viscosity change and pot-life. Complete compatibility of the IPNs was found as DGEBA content was higher than 50% by weight. The compatibility between PEGDA and DGEBA networks was evidenced from inner shift of a single damping peak in RDS. In the meantime, SEM micrographs confirmed the coincidence with the result of RDS
MASS-SPECTROMETRIC MEASUREMENTS OF CO2-LASER DISCHARGES WITH TIME RESOLUTION
(1992-08-01)
LAN, YL
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HSIEH, TC
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電子物理學系
;
Department of Electrophysics
In mass spectrometric measurements, knowledge of the gas dwell time in the glow discharge region has been utilized to time-resolve the variations of CO2 partial pressure in CO2 laser discharges. The measured data are interpreted by a dissociation-reformation scheme of CO2 molecules in the discharge. Rate coefficients that characterize the CO2 equilibrium process are evaluated, and their technical implications are discussed.
PERFORMANCE ANALYSIS OF WAVELENGTH DIVISION-MULTIPLEXING AND SUBCARRIER-MULTIPLEXING (WDM-SCM) TRANSMISSION USING FIBER BRILLOUIN AMPLIFICATION
(1992-08-01)
LEE, YH
;
WU, J
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KAO, MS
;
TSAO, HW
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電信工程研究所
A subcarrier multiplexing based optical wavelength division multiplexing system with fibre Brillouin amplification (FBA) is analysed. In the optical domain, a pump laser is tuned to amplify the corresponding optical carrier by FBA for the desired group of SCM signals. In the electrical domain, a microwave tuner is used to select the desired channel in the selected SCM group. This system has the benefits of eliminating the need for polarisation control, the ability to cancel phase noise due to the 'squaring' photodetection process of the selected optical carrier together with its SCM channels, and enhancement of optical receiver sensitivity by amplification of the carrier. Comparisons with other systems are also presented.
SELF-DIRECTIONING WITH THE REVOLVING RETROREFLECTION TECHNIQUE
(1992-08-01)
WENG, PK
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SHIE, JS
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交大名義發表
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光電工程學系
;
National Chiao Tung University
We have developed a method for giving direction and/or position information in an optical guidance system based on the pulse position modulation property of a reflected light pulse train from a revolving retroreflector. The principle and theoretical analysis are described. Experimental verification of the one-axis, closed-loop tracking system is presented, which resulted in a static angular resolution as low as 22-mu-rad. This method suggests some potential applications to coordinate determinations or line-of-sight guidance systems.
A NEW 2-DIMENSIONAL MODEL FOR THE POTENTIAL DISTRIBUTION OF SHORT GATE-LENGTH MESFETS AND ITS APPLICATIONS
(1992-08-01)
CHIN, SP
;
WU, CY
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
A new analytical technique for calculating the two-dimensional (2D) potential distribution of a MESFET device operated in the subthreshold region is proposed, in which the 2D Poisson's equation is solved by the Green's function technique. The potential and electric-field distributions of a non-self-aligned MESFET device are calculated exactly from different types of Green's function in different boundary regions, and the sidewall potential at the interface between these regions can be determined by the continuation of the electric field at the sidewall boundary. The remarkable feature of the proposed method is that the implanted doping profile in the active channel can be treated. Furthermore, a simplified technique is developed to derive a set of quasi-analytical models for the side-wall potential at both sides of the gate edge, the threshold voltage of short gate-length devices, and the drain-induced barrier lowering. Moreover, the developed quasi-analytical models are compared with the results of 2D numerical analysis and good agreements are obtained.
EXISTENCE OF POSITIVE NONRADIAL SOLUTIONS FOR NONLINEAR ELLIPTIC-EQUATIONS IN ANNULAR DOMAINS
(1992-08-01)
LIN, SS
;
交大名義發表
;
應用數學系
;
National Chiao Tung University
;
Department of Applied Mathematics
We study the existence of positive nonradial solutions of equation DELTA-u + f(u) = 0 in OMEGA(a) , u = 0 on partial derivative-OMEGA(a) , where OMEGA(a) = {x is-an-element-of R(n) : a < x < 1} is an annulus in R(n) , n greater-than-or-equal-to 2 , and f is positive and superlinear at both 0 and infinity . We use a bifurcation method to show that there is a nonradial bifurcation with mode k at a(k) is-an-element-of (0, 1) for any positive integer k if f is subcritical and for large k if f is supercritical. When f is subcritical, then a Nehari-type variational method can be used to prove that there exists a* is-an-element-of (0, 1) such that for any a is-an-element-of (a* , 1) , the equation has a nonradial solution on OMEGA(a) .
DESIGN OF A 3-DIMENSIONAL GAP-COUPLED SUSPENDED SUBSTRATE STRIPLINE BANDPASS FILTER
(1992-08-01)
CHIANG, YC
;
TZUANG, CKC
;
SU, S
;
交大名義發表
;
電信工程研究所
A three-dimensional gap-coupled suspended substrate stripline (SSS) bandpass filter, based on the modified configuration of the classic end-coupled filter, is presented. it consists of printed half-wavelength resonators placed on the same and/or the opposite sides of the suspended substrate. These resonators orient themselves in arbitrary directions. Such an arrangment makes the new filter highly flexible to interface with other microwave subcircuit modules. The filter is constructed in a bent channelised housing that suppresses any possibility of exciting higher-order modes, except the dominant quasi-TEM mode of propagation. Consequently, the channelised filter is free from any coupling between itself and other microwave circuit components within the system. Two look-up tables, derived from a variational three-dimensional quasi-TEM spectral-domain analysis of the discontinuity problems associated with the adjacent gap-coupled resonators, are incorporated into the computer-aided design of the new filter. The de-embedded discontinuity parameters are validated by comparing them with those obtained by experiment and full-wave approaches for the microstrip open-end and the SSS end-coupled problems, respectively. The measured results for the experimental 21-22 GHz bandpass filter agree very well with the theoretic predictions considering the conductor losses (5.57 x 10(-3) dB/mm) of the SSS. It has less than 1.4 dB insertion loss and greater than 10 dB return loss in the passband.