Browsing by Issue Date, starting with "1992-11-02"

Now showing 1 - 20 of 90508

SCHOTTKY-BARRIER HEIGHTS OF THE AMORPHOUS INTERLAYER SI INTERFACES IN TITANIUM THIN-FILMS ON (001)SI
(1992-11-02)
LIAUH, HR
;
CHEN, MC
;
CHEN, JF
;
CHEN, LJ
;
電子工程學系及電子研究所
Schottky barrier heights (SBHs) of amorphous interlayer/Si interfaces in Ti thin films on (001)Si have been measured by forward current-voltage technique. A-interlayers were observed to form by cross-sectional transmission electron microscopy in both Ti thin films on n- and p-type silicon systems in samples annealed at temperatures of and lower than 450-degrees-C for 30 s. Although the SBHs vary for about 0.05-0.08 eV for samples annealed over a temperature range from room temperature to 900-degrees-C, SBHs at the a-interlayer/n-Si and a-interlayer/p-Si were measured to be 0.52-0.54 and 0.59-0.57 eV, respectively. Formation of homogeneous metal a-interlayer/Si interfaces correlated with their SBHs in a number of refractory metal-silicon systems promises to greatly clarify the SBH formation mechanisms.
NONLINEAR RESPONSES OF A BUILDING STRUCTURE TO EARTHQUAKE EXCITATION
(1992-11-03)
LIOU, GS
;
KANG, YY
;
交大名義發表
;
土木工程學系
;
National Chiao Tung University
A simplified stick model for the nonlinear dynamic analysis of a building structure is presented. Based on the strong-column weak-beam design philosophy, similar deformation shapes for all the columns in the same storey of a building structure is assumed. Therefore, while subjected to horizontal earthquake excitation, the inflection points of beam elements of building structures are assumed at either the middle of the spans or the locations of the plastic hinges in beam elements. After stacking all the column lines of the building structure and making use of the technique of static condensation for the stiffness matrices of beam elements, the simplified stick model with intermediate rotational constraints at all the floor levels can be set up. Bilinear behavior for beam and column elements is adopted for the nonlinear analysis. The advantage of using the proposed stick model for nonlinear dynamic analysis is to slash the computational cost, since the number of the degrees of freedom for each floor level is only two and the bandwidth of the stiffness matrix for total structure system is four. Some numerical results and some comparisons with the results of DRAIN-TABS are presented in order to show the effectiveness of the simplified model, and some possible extentions of the stick model are also discussed.
FLUORINATED DIPHENYL-DIACETYLENE AND TOLANE LIQUID-CRYSTALS WITH LOW THRESHOLD VOLTAGE
(1992-11-09)
WU, ST
;
HSU, CS
;
CHEN, YN
;
WANG, SR
;
應用化學系
Several new fluoro-alkoxy and alkenyloxy (alkoxy with a carbon-carbon double bond) diphenyl-diacetylene and tolane liquid crystals are synthesized and their physical properties evaluated. Double bond position is found to make a pronounced effect on elastic constant, phase transition temperature and heat fusion enthalpy, but little change on birefringence, dielectric anisotropy, and viscosity. These compounds exhibit a high birefringence, low viscosity, and low threshold voltage, and are particularly attractive for infrared light valves and polymer-dispersed liquid crystal displays.
INSITU REACTED TIB2-REINFORCED ALUMINA
(1992-11-15)
CHUANG, SC
;
KUO, CT
;
HO, CT
;
LI, AK
;
機械工程學系
In situ formation of TiB2 in Al2O3 matrix through the reaction of TiO2, boron and carbon has been studied. In hot-pressed samples, in addition to TiB2, TiC and Al2TiO5, were also found to be dispersed phases in Al2O3 matrix. However, in the case of pressureless-sintered samples, pure Al2O3/TiB2 composite with > 99% relative density can be obtained through a preheating step held at 1300-degrees-C for longer than 30 min and then sintering at a temperature above 1500-degrees-C. Pressureless-sintered composite containing 20 vol % TiB2 gives a flexural strength of 580 MPa and a fracture toughness of 7.2 MPa m1/2.
FORMATION OF COBALT-SILICIDED P+N JUNCTIONS USING IMPLANT THROUGH SILICIDE TECHNOLOGY
(1992-11-15)
CHEN, BS
;
CHEN, MC
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
This paper investigates electrical and material properties of cobalt silicided p+ n junctions fabricated using implant through silicide (ITS) technology. The annealing procedure was carried out in an open-tube furnace with flowing nitrogen. To prevent residual oxygen in the furnace from reacting with the cobalt, a passivating film of molybdenum was used during the initial stage of annealing. BF2+ ion implantation was employed for the p+ n junction formation. The ITS scheme and the subsequent annealing conditions were evaluated by analysis of the material properties and investigation of the electrical characteristics of the silicided junctions. During high-temperature annealing (greater-than-or-equal-to 900-degrees-C), Co silicide releases its high surface energy via silicon precipitation and film agglomeration. High-temperature stability of the Co silicide can be improved by BF2+ ion implantation, as indicated by the retardation of film agglomeration and decreased degradation of sheet resistance. Cobalt-silicided p+ n junction diodes with 0.1 mum junction depth measured from the silicide/silicon interface were fabricated at a 700-degrees-C annealing and shown to possess excellent electrical properties. The leakage current density measured at -5 V was 0.5 nA/cm2 and a forward ideality factor of 1.006 was obtained. It was found that Co silicide is suitable to serve as an energy barrier and dopant diffusion source for the ITS scheme at low-temperature annealing. For elevated temperatures (greater-than-or-equal-to 900-degrees-C), the use of cobalt silicide as a dopant diffusion source becomes impractical because the dopant evaporation and silicide agglomeration severely degrade junction performance. Nevertheless, the silicide layer can be used as an energy barrier and implantation damage basin for high-temperature processes. No evidence of the electrically activated trapping centers related to the cobalt atoms was observed with BF2+ implantation at energies up to 100 keV. Thus, there is no fundamental limitation prohibiting the formation of cobalt-silicided shallow junctions being fabricated using ITS technology.
WAVELENGTH-DIVISION-MULTIPLEXING AND WAVELENGTH-DIVISION-DEMULTIPLEXING BY USING A SUBSTRATE-MODE GRATING PAIR
(1992-11-15)
HUANG, YT
;
SU, DC
;
TSAI, YK
;
電子工程學系及電子研究所
;
光電工程學系
We present theoretical and experimental studies of a novel substrate-mode grating pair structure for wavelength-division-multiplexing/demultiplexing applications. Normally incident coupling and on-axis output imaging with this device provide easier alignment with coupled optical fibers. We have designed and fabricated wavelength-division-multiplexing devices that are implemented by polarization-insensitive high-efficiency (> 85%) substrate-mode holograms. Three-channel demultiplexing experiments have also been successfully demonstrated with the limited available wavelength range of our diode-laser system.
THE WORST CASE ANALYSIS OF ALGORITHM ON MULTIPLE STACKS MANIPULATION
(1992-11-19)
CHIEN, BC
;
YANG, WP
;
資訊工程學系
;
Department of Computer Science
NONASSOCIATIVE PARALLEL PREFIX COMPUTATION
(1992-11-19)
CHEN, RJ
;
HOU, YS
;
交大名義發表
;
資訊工程學系
;
National Chiao Tung University
Associativity of a binary operation allows many applications that are not possible with a non-associative binary operation. We propose a method to transform a binary expression into an associative one and present two related applications.
INFLUENCES OF HARMONIC COUPLING ON BIFURCATIONS IN DUFFING OSCILLATOR WITH BOUNDED POTENTIAL WELL
(1992-11-22)
KAO, YH
;
WANG, CS
;
YANG, TH
;
電信工程研究所
;
光電工程學系
DIAMOND FILM GROWTH ON CEMENTED TUNGSTEN CARBIDES STUDIED BY SEM, AES AND XPS
(1992-11-23)
CHEN, JL
;
HUANG, TH
;
PAN, FM
;
KUO, CT
;
CHANG, CS
Diamond films were deposited on cemented WC substrates using a hot filament chemical vapor deposition (CVD) system with a mixture of CH4 and H-2 as the source gases. The effect of the surface pretreatments of scratching the surface and etching to remove the surface Co from the substrate on diamond nucleation and growth was studied. The effect of CH4 Concentration on diamond growth was also examined. Scanning electron microscopy, Auger electron, X-ray photoelectron and energy dispersive spectroscopies were used to examine the film morphology, quality and compositions. The results show that a good diamond-crystal quality can be obtained by reducing the surface Co content in the substrate to below 1%. Co in the surface layer of the substrate inhibits both diamond nucleation and growth. Polishing and etching treatments to scratch the surface and to remove the surface Co of the substrates are essential to maintain the surface roughness in an appropriate range to obtain diamond films with a good quality and adhesion. A change in CH4 Concentration in the source gases from 0.5 to 0.15% can change the preferred orientation of the diamond films fro m the {100} to the {111} plane.
THE ROLE OF HYDROGEN IN DIAMOND SYNTHESIS FROM CARBON-DIOXIDE HYDROCARBON GASES BY MICROWAVE PLASMA CHEMICAL VAPOR-DEPOSITION
(1992-11-23)
CHEN, CF
;
HONG, TM
;
交大名義發表
;
材料科學與工程學系
;
National Chiao Tung University
We utilized carbon dioxide to replace hydrogen in CO2-(CH4, C2H2, C3H8) gas mixtures and studied the effect on diamond growth of adding a small amount of hydrogen to the system. The deposits were analyzed by scanning electron microscopy, X-ray diffraction, and Raman spectroscopy. Our results showed that diamond film with high growth rate and good crystallinity could be obtained in these systems without supplying additional hydrogen gas. When the amount of hydrogen was increased, all the deposited film in the systems gradually displayed poorer morphology and crystallinity. This indicates that graphitic or amorphous carbon components in the diamond film increased with the addition of hydrogen, with a resulting negative effect on the quality of the diamond film. The influence of hydrogen on diamond growth is also investigated in this study by comparing growth rates and C:H:O ratios among various CO2-(CH4, C2H2, C3H8) systems.
GATE AND DRAIN CURRENTS IN OFF-STATE BURIED-TYPE P-CHANNEL LDD MOSFETS
(1992-12-01)
CHEN, MJ
;
CHAO, KC
;
HUANG, TH
;
TSAUR, JM
;
電控工程研究所
The buried-type p-channel LDD MOSFET's biased at high positive gate voltage exhibit new characteristics: 1) the ratio of the drain to gate currents is about 1 X 10(-3) to 5 X 10(-3); and 2) the gate and drain currents both are functions of only the gate voltage minus the n-well bias. Such characteristics are addressed based on the formation of the surface n+ inversion layer due to the punchthrough of the buried channel to the underlying shallow p-n junction. The measured gate current is due to the Fowler-Nordheim tunneling of electrons from this inversion layer surface and the holes generated within the high-field oxide constitute the drain current. The n+ inversion layer surface potential is found to be equal to the n-well bias plus 0.55 V. As a result, not only the oxide field but also the gate and drain currents are independent of drain voltage.
ORIENTATION-DEPENDENT X-RAY ABSORPTION FINE-STRUCTURE (XAFS) OF THE BI-SR-CA-CU-O SYSTEM
(1992-12-01)
CHOU, CH
;
PONG, WF
;
SHI, JB
;
KU, HC
;
LIN, IN
Using the transmission and fluorescence modes at the National Synchrotron Light Source (NSLS) X-23A2 beam line, we have measured polarized XAFS spectra of the Bi, Pb L3-edges and the Cu K-edge for the (Bi1.85Pb0.15)Ca2.2Sr1.8Cu3O10+delta sample and unpolarized XAFS spectra of the Bi, Pb L3-edges and the Cu K-edge for Bi2Ca1.2Sr1.8Cu2O8+delta, Pb0.2Bi1.9Sr1.9Cu1O6+delta and (PbxBi2-x)Sr2Ca2Cu3Oy (x = 0, 0.2, 0.4) samples. All XAFS spectra were measured at room temperature. The incommensurate modulations in the Bi-O layers are discussed in terms of the XAFS technique. The XAFS spectra of Bi L3-edge do not vary substantially for different sample orientation with respect to the X-ray polarization vector E. There is evidence for the existence within the Bi-Sr-Ca-Cu-O system of Bi atoms having the oxidation number exceeding 3. Pb ions predominantly substitute for Bi ions in the Bi-Sr-Ca-Cu-O system because there is no significant difference between the XANES spectra of the Pb and Bi L3-edges, respectively. The oxidation numbers of substituted Pb in Bi-Sr-Ca-Cu-O system differ much from those of Pb in PbO2 in which the oxidation number of all Pb atoms is 4. In agreement with other investigators, our results on the polarized XANES spectra of the Cu K-edge indicate that a satellite about 7 eV above the main K-XANES peak in both polarizations is a multielectron excitation to the final-state configuration 1s3d9epsilonp1, and that a shoulder on the rising absorption edge, present for many Cu compounds and generally assigned to a shake-down multielectron excitation, is a transition to a final state of the Cu compounds. We have also deduced that the structure of the Cu-O planes in the Bi-Sr-Ca-Cu-O samples is ordered.
SIZE EFFECT ON THE ELECTRICAL-CONDUCTION AND NOISE OF RUO2-BASED THICK-FILM RESISTORS
(1992-12-01)
CHIOU, BS
;
SHEU, JY
;
WU, WF
;
電控工程研究所
;
Institute of Electrical and Control Engineering
Temperature dependence of sheet resistance for a generic RuO2-based resistor with a composition of 20 wt.% RuO2-80 wt.% glass (63 wt.% PbO-25 wt.% B2O3-12 wt.% SiO2) is evaluated. A combined tunnel/parallel conduction model is employed to describe the resistance behavior with respect to the temperature variation. The geometry of the resistive film, such as the aspect ratio and thickness, cast a significant effect on the electrical characteristic of the thick film assembly. It is observed that shorter resistive films exhibit smaller resistivity as compared to that of the longer film. Thinner resistive films have smaller resistivity as compared to the thicker ones. In addition, 1/f noise is the dominating contribution in the thick film resistor. The presence of 1/f noise can be qualitatively explained with the aid of the tunneling mechanism.
EFFECT OF COPPER ADDITIVE ON THE MICROSTRUCTURE AND ELECTRICAL-PROPERTIES OF POLYCRYSTALLINE ZINC-OXIDE
(1992-12-01)
CHIOU, BS
;
CHUNG, MC
;
交大名義發表
;
電子工程學系及電子研究所
;
National Chiao Tung University
Nonohmic behavior is obtained for polycrystalline ZnO with copper as the only additive in the range 0.3 less-than-or-equal-to x less-than-or-equal-to 1 wt%. The effect of copper on the microstructure and electrical behavior of ZnO:Cu ceramics is investigated. The leakage current decreases and the breakdown electric field increases as the copper concentration increases. The large apparent dielectric constant of ZnO:Cu ceramic (k > > k(ZnO), k(ZnO) is the dielectric constant of pure ZnO) is attributed to the grain boundary barrier layer effect. A Schottky barrier height of 0.27-0.46 eV is obtained for various copper-added samples, depending on sintering temperatures.
HIGH-ORDER HARMONIC-GENERATION IN ATOMIC-HYDROGEN AT 248-NM - DIPOLE-MOMENT VERSUS ACCELERATION SPECTRUM
(1992-12-01)
JIANG, TF
;
CHU, SI
;
電子物理學系
;
Department of Electrophysics
We present a study of the high-order harmonic-generation (HG) spectra of atomic hydrogen at 248 nm based on the Fourier transform of the expectation values of the induced dipole moment and acceleration. The calculations were performed by extending a fast-Fourier-transformation split-operator technique (in spherical coordinates) to the solution of the time-dependent wave functions in intense laser fields. It is seen that the acceleration form provides a more satisfactory and accurate framework for the study of the photoemission HG spectrum at very intense fields, particularly when ionization becomes appreciable.
CHARACTERISTICS OF THE GAIN AND SIGNAL-TO-NOISE RATIO OF A DISTRIBUTED ERBIUM-DOPED FIBER AMPLIFIER
(1992-12-01)
WEN, SF
;
CHI, S
;
光電工程學系
;
Department of Photonics
The effects of the stimulated Ramam scattering (SRS) on the gain and signal-to-noise ratio (SNR) of the DEDFA with 100-km fiber length and with bidirectional pumps are numerically studied. It is found that the gain and SNR are significantly enhanced by the SRS with practical parameters. For 1.55-mum signal and 10-muW initial signal power, there are 8.8-dB gain enhancement and 3.3-dB SNR enhancement for 1.48-mum pump wavelength and 75-mW initial pump power. The characteristics of the gain and SNR enhancements due to SRS are studied for different signal wavelength, signal powers, pump wavelengths, pump powers, and effective fiber cross sections. The results show that the gain and SNR are decreased by SRS only for the unpractical high pump power and/or small effective fiber cross section.
A NEW METHODOLOGY FOR 2-DIMENSIONAL NUMERICAL-SIMULATION OF SEMICONDUCTOR-DEVICES
(1992-12-01)
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 methodology for obtaining the self-consistent solution of semiconductor device equations discretized in the finite-difference scheme is proposed, in which a new discretized Green's function solution method is used to solve the two-dimensional discretized Poisson's equation and a surface mapping technique is developed to treat arbitrary surface boundary conditions. As a result of the proposed new solution method, the two-dimensional potential distribution can be expressed in terms of charge density distribution and bias conditions. Using the derived potential distribution, the SLOR-nonlinear iteration for the current continuity equations of both carriers can be performed by incorporating with a new algorithm to get the self-consistent solution of full set of semiconductor device equations without any outer iteration. Comparisons between the proposed method and the Gummel's method in Si-MESFET simulation are made. It is demonstrated that the convergent rate of the proposed method can be speeded up to 4-8 times over the Gummel's method. The proposed new iterative method can be incorporated with the conventional solution method such as the Gummel's method to get a stable and efficient computation scheme for device simulation.
ONLINE METHOD FOR MEASUREMENT OF THE DISPERSION COEFFICIENT OF RADIONUCLIDE MIGRATION USING A COLUMN METHOD
(1992-12-01)
LIU, WC
;
LO, JG
;
TSAI, CM
;
環境工程研究所
;
Institute of Environmental Engineering
An On-line method to obtain breakthrough curves from a conservative tracer generated in crushed rock columns has been introduced. The breakthrough curve can be used to evaluate some important hydrologic Parameters for studying radionuclide migration in groundwater system. These parameters include the dispersion coefficient, average flow yelocity, effective porosity, and retardation factor of the columns tested. A conservative radiotracer, I-131, was used to generate the breakthrough curves, and linear regression analysis was applied to obtain the optimum value of dispersion coefficient. The effects of the injected volume of radioactive tracer, average flow velocity, and effective diameter of packed material on the dispersion coefficient as well as the stability of the packed material, and their in-situ application are discussed.
ON EQUIVALENT SYSTOLIC DESIGNS OF LU DECOMPOSITION AND ITS ALGEBRAIC REPRESENTATION
(1992-12-01)
HOU, YC
;
TSAY, JC
;
交大名義發表
;
資訊工程學系
;
National Chiao Tung University
Algorithms which are to be mapped onto interconnecting processing elements in order to design a systolic array are conventionally represented by graphs or networks. This paper introduces the concept of algebraic representation and uses a generating function to represent a systolic array.