Browsing by Issue Date, starting with "1993-06-15"

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FREE-CARRIER ABSORPTION OF NONDEGENERATE SEMICONDUCTORS IN QUANTIZING MAGNETIC-FIELDS - NONPOLAR OPTICAL PHONON-SCATTERING
(1993-06-15)
WU, CC
;
LIN, CJ
;
應用數學系
;
電控工程研究所
;
Department of Applied Mathematics
The effect of nonpolar optical phonon scattering on the free-carrier absorption in n-type semiconductors such as germanium has been investigated quantum mechanically in quantizing magnetic fields. It is assumed that the energy band structure of electrons in semiconductors is nonparabolic and the dominant scattering mechanism for conduction electrons is of the nonpolar optical phonon scattering. When the radiation is polarized parallel to a dc magnetic field B, the absorption coefficient appears to be of a complex value due to the interaction between the radiation field and the optical phonon field in nondegenerate semiconductors. Results show that the real part of the absorption coefficient oscillates with the magnetic field in the high-field region, and imaginary part of the absorption coefficient appears with a few extremum points (peaks and dips) in high magnetic fields. These are different from those of the acoustic phonon scattering in III-V compound semiconductors such as InSb or GaAs, in which the absorption coefficient oscillates with the magnetic field in lower magnetic fields and then increases monotonically with the field.
ROLE OF CLADDING LAYER THICKNESSES ON STRAINED-LAYER INGAAS/GAAS SINGLE AND MULTIPLE-QUANTUM-WELL LASERS
(1993-06-15)
LIU, DC
;
LEE, CP
;
TSAI, CM
;
LEI, TF
;
TSANG, JS
The influences of cladding layer thicknesses on the performance of strained-layer InGaAs/GaAs graded-index separated confinement heterostructure quantum well lasers have been studied. The waveguiding property of the laser structure was analyzed using the transfer matrix method. In this work, experimental results and the calculated results showed that threshold current densities and external quantum efficiencies both were crucially dependent on the thicknesses of cladding layer for both single and multiple quantum well lasers. The minimum cladding layer thicknesses needed to maintain low threshold current densities and low internal total loss for both single and multiple quantum well devices were determined experimentally and theoretically.
這枝筆
(1993-06-18)
魏子雲
DOPING OF INGAP EPITAXIAL LAYERS GROWN BY LOW-PRESSURE METAL-ORGANIC CHEMICAL-VAPOR-DEPOSITION
(1993-06-20)
WU, CC
;
LIN, KC
;
CHAN, SH
;
FENG, MS
;
CHANG, CY
DEZn and H2Se were utilized as p- and n-type dopant sources for the growth in InGaP layers by low pressure metal-organic chemical vapor deposition (LP-MOCVD). The decrease in intensity of the extra spots of electron diffraction indicates that disordering is induced by the zinc doping. Streaky and wavy diffraction patterns demonstrate the formation of anti-phase domains caused by the Se dopant incorporation. The growth rate of the grown layer is reduced by more than 10% owing to the dopant incorporation. A photoluminescence emission energy difference of 141 meV between undoped and Zn-doped (5.8 x 10(18) cm-3) InGaP was obtained. The effects of doping on disordering, degeneracy of quasi-Fermi level and lattice constant reduction of grown layers were included in this study.
EFFECT OF AG2O ADDITIVE ON MICROSTRUCTURE AND SUPERCONDUCTIVITY OF THE TL2BA2CA2CU3OY COMPOUND
(1993-06-21)
KOO, HS
;
HURNG, WM
;
LEE, WH
;
TSENG, TY
;
CHEN, M
A series of Ag-doped Tl2Ba2Ca2Cu3Oy superconducting Oxides were prepared by a solid-state reaction and the influence of Ag2O content, with a varying molar ratio which ranged from 0 to 1.0, was also investigated. The normal-state resistance of the samples decreased with an increase in the content of Ag2O additive, while the critical superconducting temperatures of the Ag-doped samples increased once the Ag2O content was increased. The doping of the silver oxide was indicated from the results of the x-ray diffraction pattern to be favorable to the formation of the three CuO layers with a high-T(c) phase T12Ba2Ca2Cu3Oy. The diamagnetic Property of the samples was also confirmed by the magnetic measurements to become enhanced by doping with silver oxide. The platelike grains of Tl2 Ba2CaCu2Oy phase Were Observed from scanning electron micrographs to be primarily present in the undoped sample, while the amount of the needlelike Tl2Ba2Ca2Cu3Oy grain increased with an increase in the doping amount of Ag2O.
THICKNESS DETERMINATION OF POLY-SI/POLY-OXIDE POLY-SI/SIO2/SI STRUCTURE BY ELLIPSOMETER
(1993-06-24)
CHAO, TS
;
LEE, CL
;
LEI, TF
;
電控工程研究所
;
Institute of Electrical and Control Engineering
An ellipsometry measurement method is proposed to measure the poly-Si/poly-oxide/poly-Si/SiO2/Si structure. The thickness of each layer in this structure can be easily obtained by a conventional ellipsometry measurement. The measured result is consistent with that of cross-sectional TEM.
RF MAGNETRON-SPUTTERED INDIUM TIN OXIDE FILM ON A REACTIVELY ION-ETCHED ACRYLIC SUBSTRATE
(1993-06-25)
CHIOU, BS
;
HSIEH, ST
;
電子工程學系及電子研究所
;
電控工程研究所
;
Department of Electronics Engineering and Institute of Electronics
Indium tin oxide (ITO) films were deposited onto acrylic substrates with r.f. magnetron sputtering. The substrate temperature was kept below 65-degrees-C and the sputtering power was 18 W to prevent the acrylic from deformation. The adhesion strength of the ITO film on acrylic is improved by reactive ion etching (RIE) of the substrate. However, the transmission of the ITO on RIE-treated acrylic is smaller than that of the ITO on as-received acrylic. A transmission of about 83% is obtained for this low temperature, low power processed ITO film. Both the absorption coefficient and the transition energy gap are evaluated. The figure of merit of films on acrylic substrates ranges from 11.4 to 38.6 x 10(-3) OMEGA-1.
2-COLOR INFRARED PHOTODETECTOR USING GAAS/ALGAAS AND STRAINED INGAAS/ALGAAS MULTIQUANTUM WELLS
(1993-06-28)
TSAI, KL
;
CHANG, KH
;
LEE, CP
;
HUANG, KF
;
TSANG, JS
A two-color infrared detector using GaAs/A]GaAs and strained InGaAs/AlGaAs multiquantum wells is demonstrated. The response peak of the GaAs/AlGaAs quantum well is at 8 mum, and that of the InGaAs/AlGaAs quantum well is at 5.3 mum. The responsivity of the detector is 1 A/W at 8 mum and 0.27 A/W at 5.3 mum; these are the best values reported for a two-color quantum well infrared detectors (QWIPs) with peak sensitivities in the spectral regions of 3-5.3 mum and 7.5-14 mum. Single-colored 5.3 and 8 mum QWIPs were also fabricated to study the bias dependent behavior. This behavior can be explained using the concept of current continuity. Because of a higher electrical resistance, a high electric field domain is always formed first in the shorter wavelength quantum well stack.
ULTRATHIN TEXTURED POLYCRYSTALLINE OXIDE WITH A HIGH ELECTRON CONDUCTION EFFICIENCY PREPARED BY THERMAL-OXIDATION OF THIN POLYCRYSTALLINE SILICON FILM ON N+ POLYCRYSTALLINE SILICON
(1993-06-28)
WU, SL
;
LEE, CL
;
LEI, TF
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
This letter presents an ultrathin textured polycrystalline oxide (polyoxide) (less-than-or-equal-to 100 angstrom) prepared by thermal oxidation of thin polycrystalline silicon (polysilicon) film on n+ polysilicon. The presented textured polyoxide exhibits a much higher electron injection efficiency, a much smaller electron trapping rate, and a much larger charge to breakdown than the normal polyoxide. The value of Q(bd) of the textured polyoxide could be more than 3000 C/cm2 even under 100 mA/cm2 stressing.
MOMENT-PRESERVING EDGE-DETECTION AND ITS APPLICATION TO IMAGE DATA-COMPRESSION
(1993-07-01)
HSU, HS
;
TSAI, WH
;
資訊科學與工程研究所
;
Institute of Computer Science and Engineering
In contrast to the numerous edge-detection techniques that detect edges either point by point or using overlapping circular windows, an edge detector using nonoverlapping rectangular windows is proposed. The detector examines the pixels within each rectangular window of an image, and decides whether an edge element is present or not in the window. Based on the gray and mass moment-preserving principles, the step edge is estimated locally to subpixel accuracy using analytical formulas. To apply the edge detection results to image compression, the detected edge elements are then tracked and grouped based on proximity and orientation. Using the line parameters of the grouped edge elements, region boundaries are approximated in a piecewise linear manner. This reduces the amount of data required to describe region shapes and is useful for compressing some types of images. Good experimental results of compressing character and trademark images are also included to show the feasibility of the proposed approach.
ADAPTABLE QUAD TREE TECHNIQUES
(1993-07-01)
SU, SJ
;
KUO, YS
;
TSAY, JC
;
資訊工程學系
;
Department of Computer Science
The quad tree is a widely used data structure for region queries. Quad trees normally perform reasonably efficient on the majority of layout data, but could perform very poor on certain extreme data. This demonstrates the quad tree's deficiency in its adaptability to peculiar layout data. We address two aspects of the adaptability problem. On the one hand, the threshold of a quad tree is allowed to change in order to match the global complexity of the layout. On the other hand, a new quad subdivision criterion is developed which adapts a quad tree to the nonuniform distribution of objects with various sizes. Experiments have indicated that the two techniques are indeed useful in coping with the peculiarity of extreme layout data.
A HOLOGRAPHIC LENSLET ARRAY DEVICE WITH VARIABLE FOCAL POWER
(1993-07-01)
TSAI, YK
;
SU, DC
;
HUANG, YT
;
電子工程學系及電子研究所
;
光電工程學系
A holographic lenslet array device with variable focal power is presented. It consists of two holo-lenslet array components. The i x jth pair of the holo-lenslets between two components forms a channel, which has a symmetrical off-axis configuration formed by a Leith-Upatnieks holo-lenslet and a Brandt holo-lenslet. Because of its variable focal power, it is more flexible than others. It can achieve the function of multi-signal processing, and can be used as array illuminators for the optical parallel interconnect applications.
DESIGN OF PSEUDOEXHAUSTIVE TESTABLE PLA WITH LOW OVERHEAD
(1993-07-01)
SHEN, WZ
;
HWANG, GH
;
HSU, WJ
;
JAN, YJ
;
電控工程研究所
The pseudoexhaustive testing (PET) scheme is a economic approach to test a large embedded programmable logic array (PIA). In this paper, we propose an efficient algorithm named low overhead PET (LOPET) to partition the product lines. By applying our algorithm, both the area overhead and test length are reduced significantly.
ON PARALLELIZING THE DEMPSTER-SHAFER METHOD USING TRANSPUTER NETWORK
(1993-07-01)
WONG, YC
;
HWANG, SY
;
資訊工程學系
;
Department of Computer Science
Manipulating uncertain information is a necessary capability for any intelligent system. Several approaches, such as the Bayesian theory, Certainty Factors, and the Dempster-Shafer method, have been proposed to handle uncertainty. Among them the Dempster-Shafer method is the most theoretical sound and consistent with human behavior; however, it is argued on its computational complexity. This article presents a parallel reasoning algorithm based on the Dempster-Shafer method and implements it on the transputer network. We first analyze the best topologies of the transputer network with various numbers of processors; then the performance of the parallel program, such a speedup and efficiency, is measured on these best topologies.
SYNTHESIS, CHARACTERIZATION, AND KINETIC-STUDY OF COMPATIBLE SINS BASED ON DIALLYL PHTHALATE AND EPOXY-RESIN
(1993-07-01)
LIN, MS
;
YEH, CC
;
交大名義發表
;
應用化學系
;
National Chiao Tung University
Diallyl phthalate (DAP) was blended with diglycidyl ether of bisphenol A (DGEBA) in various weight ratios: 100 / 0, 75 / 25, 50 / 50, 25 / 75, and 0 / 100. These blends were then cured simultaneously with dicumyl peroxide (DCP) and hexahydrophthalic anhydride (HHPA) in conjunction with 2-cyanoethyl-4-methyl immidazole (EMI-CN, 0.5% as catalyst) to obtain simultaneous interpenetrating polymer networks (SIN's). H-bonding between DAP and DGEBA was detected with FTIR. The SIN's thus obtained were characterized with rheometric dynamic spectroscopy (RDS) and differential scanning calorimeter (DSC) to check the compatibility of components. Gel fractions were measured with a Soxhlet extractor. Viscosity increases of all SIN's were measured with a Brookfield viscometer at curing temperatures. Conversions of C = C and epoxide versus cure time were monitored with FTIR and kinetic parameters were calculated and discussed. Experimental results revealed that H-bonding in the DAP / DGEBA blends was evidenced from the shift of the IR band (nu(C=O)) to a lower wave number, as well as the shift of epoxide band (nu(DELTA)) to a higher wave number. Complete compatibility between DAP and DGEBA was supported from the single damping peak in DRS and single glass transition in DSC for each of SIN's. Cure dynamic DSC showed shifts of exothermic peaks to higher temperatures for all SIN's. During SIN formation, the slower viscosity increases of SIN's were found, compared with pure DAP and pure DGEBA, indicating retarded cure rates for all SIN's. In addition, lower gel fractions of SIN's were observed, indicating incomplete cure of SIN's. The retarded cure rate was further confirmed by kinetic study. Lower rate constants with higher activation energies for all SIN's were found. An effect of network interlock was proposed to account for these findings.
INFLUENCE OF SINTERING TEMPERATURE ON ELECTRICAL-PROPERTIES OF ZNO VARISTORS
(1993-07-01)
BAI, SN
;
TSENG, TY
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
The electrical properties of the ZnO varistors are demonstrated in this present study to be affected by the sintering temperature. The variation of the non-ohmic behavior with sintering temperature is indicated from I-V and C-V measurements to be a result of the changes of the interface defect density at the grain boundaries and the donor concentration in the ZnO grains. A shallow Schottky barrier is formed as a result of a low interface defect density, which is caused by losing the liquid-phase sintered materials, such as Bi2O3, when the metal oxide additives along the grain boundaries are sintered at a high temperature. The dielectric characteristic of the ZnO varistors is also affected by the sintering temperature. From the dielectric loss analysis and the complex-plane analysis it is found that there are two intrinsic defects, V0 and Zn(i), within the ZnO varistors. The natures of these defects as a function of sintering temperature are also mentioned.
NEW PHYSICAL FORMULATION OF THE THERMIONIC EMISSION CURRENT AT THE HETEROJUNCTION INTERFACE
(1993-07-01)
CHANG, KM
;
TSAI, JY
;
CHANG, CY
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
The thermionic emission current for electrons across the heterointerface is classically modeled as the difference between two opposing electron fluxes. Here we have developed a new consistent physical model, which includes the carrier degeneracy and nonideal behavior effects, for thermionic emission current at the heterojunction interface. It is shown that the thermionic emission current at the heterojunction interface can be expressed in a simple closed-form formalism which gives the relations among the average directional thermal velocity of electrons, the conduction band discontinuity, and the carrier activities at both sides of the interface. We also discuss the conditions under which the thermionic emission occurs at the heterointerface.
VISUAL COMMUNICATIONS AND IMAGE-PROCESSING IV
(1993-07-01)
CHEN, CT
;
HANG, HM
;
TZOU, KH
;
電信研究中心
;
Center for Telecommunications Research
EXISTENCE OF SIMILARITY SOLUTIONS FOR SURFACE-TENSION DRIVEN FLOWS IN FLOATING RECTANGULAR CAVITIES
(1993-07-01)
CHEN, YY
;
HWANG, TW
;
WANG, CA
;
應用數學系
;
Department of Applied Mathematics
We consider the following problem: f''' + Q . [Af f'' - (f')2] = beta, (Q, beta is-an-element-of R, A greater-than-or-equal-to 0), f(0) = f(1) = f''(1) = f''(0) + 1 = 0, which arises from the steady surface-tension driver flows in floating rectangular cavities. In this paper, we first classify all possible solutions and obtain that the given problem can only possess, at most, three types of solutions for A greater-than-or-equal-to 1. By the classification, we further verify that for every Q greater-than-or-equal-to 0 or beta greater-than-or-equal-to 0, the problem has at least one solution if A greater-than-or-equal-to 1. Moreover, if 1 less-than-or-equal-to A less-than-or-equal-to 3/2, multiple solutions also exist for sufficiently large Q > 0.
REACHING APPROXIMATE AGREEMENT ON HYPERCUBE
(1993-07-01)
CHENG, RL
;
CHUNG, CP
;
資訊科學與工程研究所
;
Institute of Computer Science and Engineering
The interactive convergence algorithm has been used for reaching agreement in systems with multiple procesors. This algorithm must utilize a broadcast mechanism regardless of the underlying architecture. This paper proposes an appropriate algorithm, the local interactive convergence algorithm, for reaching an approximate agreement on systems with high locality. The hypercube is one such system, and it is used as a vehicle for studying the algorithm. This algorithm requires only local information with simple computation. Convergence rate analysis shows that the local interactive convergence algorithm is able to achieve an approximate agreement in a predetermined rate.