Browsing by Issue Date, starting with "1994-10-06"

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HETEROTIC MASSIVE EINSTEIN-YANG-MILLS-TYPE SYMMETRY AND WARD IDENTITY
(1994-10-06)
LEE, JC
;
物理研究所
;
Institute of Physics
We show that there exist spontaneously broken symmetries for massive modes with transformation parameters theta((ab)) ([mu>upsilon]) theta((ab)) (mu) etc, containing both Einstein and E(8) circle times E(8) (or 50(32)) Yang-Mills indices in the 10D Heterotic string. The corresponding on-shell Ward identities are also constructed.
說一部「乾隆版木刻大藏經」的閒話
(1994-10-08)
管管
SPONTANEOUS FORMATION OF AL RICH AND GA RICH ALXGA1-XAS/ALYGA1-YAS SUPERLATTICE AND STRONG ENHANCEMENT OF OPTICAL-PROPERTIES
(1994-10-10)
CHIN, A
;
HSIEH, KY
;
LIN, HY
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Long range composition ordering and spontaneous formation of Al rich and Ga rich AlxGa1-xAs/AlyGa1-yAs superlattice were demonstrated. This was observed by cross-sectional transmission electron microscopy (TEM) in a 280 angstrom Al0.4GaAs quantum well laser diode heterostructure with Al0.7GaAs barriers grown on (111)B GaAs substrates. On the contrary, none of above superstructure was observed by TEM on a side-by-side grown (100) oriented substrate. More evidence is shown in the (111)B Al0.7GaAs barriers which were disordered due to a high growth temperature and did not show any superstructure. 10 K photoluminescence was shown with 32 meV redshift and a 12-times peak intensity enhancement in (111)B orientation. (C) 1994 American Institute of Physics.
CHARACTERIZATION OF THE SI/SIGE HETEROJUNCTION DIODE GROWN BY ULTRAHIGH-VACUUM CHEMICAL-VAPOR-DEPOSITION
(1994-10-15)
JUNG, TG
;
CHANG, CY
;
LIU, CS
;
CHANG, TC
;
LIN, HC
The unipolar Si/SiGe heterojunction diode grown by ultrahigh vacuum chemical vapor deposition at 550-degrees-C is demonstrated. The dark current density measured at 77 K is (2.5 +/- 0.1) x 10(-7) A/cm2 for the barrier height of 176 +/- 8 meV, at a reverse bias of 1 V. The barrier heights are measured from the activation analysis of the saturation current and compared to the theoretical values. The barrier height decreases as the thickness of the SiGe strained layer exceeds the critical thickness.
CALCULATION OF HOLE MOBILITY IN DOPED SIGE ALLOYS USING A MONTE-CARLO METHOD WITH A BOND ORBITAL BAND-STRUCTURE
(1994-10-15)
LIOU, TS
;
WANG, TH
;
CHANG, CY
;
交大名義發表
;
電子工程學系及電子研究所
Hole mobility in strained Si1-xGex/Si(001) layers is calculated as functions of temperature and doping concentration for various Ge contents using a Monte Carlo technique. In the Monte Carlo simulation, the band structure is computed by using a bond orbital model, which combines the k.p and the tight-binding methods with a strain Hamiltonian. The Fermi-Dirac distribution is employed for heavily doped impurity scattering. The alloy interaction potential of 1.0 eV for the Monte Carlo model is obtained by fitting the measured velocity-field characteristics in strained Si1-xGex alloys. The calculated hole mobilities compare well with experimental results. The strain effect on hole transport is also evaluated.
SELECTIVE EPITAXIAL-GROWTH OF GAINP BY LOW-PRESSURE METAL-ORGANIC CHEMICAL-VAPOR-DEPOSITION USING ETHYLDIMETHYLINDIUM AS IN-SOURCE
(1994-10-24)
CHAN, SH
;
SZE, SM
;
CHANG, CY
;
LEE, WI
;
電子物理學系
We have demonstrated the feasibility of selective epitaxial growth (SEG) of GaInP using low-pressure metal-organic chemical-vapor deposition (LPMOCVD) with the combination of ethyldimethylindium (EDMIn) and triethylgallium (TEGa) as the group-III sources. Complete selective epitaxy can be achieved at a growth temperature of 675 degrees C and a growth pressure of 40 Torr. The deposition of Ga-rich polycrystalline GaInP on Si3N4 film occurs at lower temperatures. Although the incorporation efficiency of TEGa into GaInP is much lower than that of trimethylgallium, the combination of EDMIn and TEGa has been found to be a good candidate for SEG of GaInP. Low-temperature photoluminescence shows that the selectively grown epitaxial layer has good optical quality and is useful for light emitting device applications. (C) 1994 American Institute of Physics.
HANDLING MULTICRITERIA FUZZY DECISION-MAKING PROBLEMS BASED ON VAGUE SET-THEORY
(1994-10-24)
CHEN, SM
;
TAN, JM
;
交大名義發表
;
資訊工程學系
;
National Chiao Tung University
New techniques for handling multicriteria fuzzy decision-making problems based on vague set theory are presented. The proposed techniques allow the degrees of satisfiability and non-satisfiability of each alternative with respect to a set of criteria to be represented by vague values. Furthermore, the proposed techniques allow the decision-maker to assign a different degree of importance to each criteria. The techniques proposed in this paper can provide a useful way to efficiently help the decision-maker to make his decisions.
OBSERVATION OF THE SUPPRESSION OF THE STIMULATED HYPER-RAMAN SCATTERING (S-3(1/2)-P-4(3/2)) NEAR THE SODIUM 4D 2-PHOTON RESONANCE
(1994-10-28)
LU, MH
;
LIU, YM
;
交大名義發表
;
光電工程學系
;
National Chiao Tung University
The stimulated hyper-Raman scattering (SHRS) emissions associated with the excitation of the 4P(3/2) state in sodium vapour have been observed in both the forward and backward directions as the pumping laser was tuned near the 3S-4D two-photon resonance. The results show that though the forward SHRS process is greatly reduced by a destructive interference between it and the four-wave mixing (FWM) process induced by itself, the forward SHRS emission has a positive gain and can still be observed under a certain condition.
NATURAL-CONVECTION IN AN ENCLOSURE WITH NONUNIFORM WALL TEMPERATURE
(1994-11-01)
FU, WS
;
TSENG, CC
;
CHEN, YC
;
交大名義發表
;
機械工程學系
A numerical study of natural convection in an enclosure was investigated. The heated wall of the enclosure is divided into two of the higher and lower temperature regions and the temperature of the cold wall is maintained at a constant. The parameters of Rayleigh number and length ratio are mainly considered. The results show that the local Nusselt number distribution varies drastically at the intersection of the higher and lower temperature regions, and the flow is strongly affected by the above two parameters.
A NEW DYNAMIC ACCESS-CONTROL SCHEME BASED ON SUBJECT-OBJECT LIST
(1994-11-01)
HWANG, MS
;
YANG, WP
;
資訊工程學系
;
Department of Computer Science
The topic of access control modes is a very important subject in the field of information protection systems. In this paper, we shall propose a new access control mode, the subject-object-list (SO-list), for a system which adds, removes, and updates subjects and objects frequently. The main advantage of the SO-list is that the number of lists remains constant despite the changes in the number of subjects/objects. Furthermore, by applying the key-lock-pair mechanism to the list, we allow a new subject/object to be added to or an existing subject/object to be removed from the system without recomputing a large number of key/lock values. Thus, our method achieves real dynamicism.
A 10-B 225-MHZ CMOS DIGITAL-TO-ANALOG CONVERTER (DAC) WITH THRESHOLD-VOLTAGE COMPENSATED CURRENT SOURCES
(1994-11-01)
CHIN, SY
;
WU, CY
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
This paper describes a 10-b high-speed COMS DAC fabricated by 0.8-mu m double-poly double-metal CMOS technology. In the DAC, a new current source called the threshold-voltage compensated current source is used in the two-stage current array to reduce the linearity error caused by inevitable current variations of the current sources, In the two-stage weighted current array, only 32 master and 32 slave unit current sources are required. Thus silicon area and stray capacitance can be reduced significantly. Experimental results show that a conversion rate of 125 MHz is achievable with differential and integral linearity errors of 0.21 LSB and 0.23 LSB, respectively. The power consumption is 150 mW for a single 5-V power supply. The rise/fall time is 3 ns and the full-scale settling time to +/- 1/2 LSB is within 8 ns. The chip area is 1.8 mm x 1.0 mm.
ELECTRICAL-PROPERTIES OF MULTILAYER-CHIP ZNO VARISTORS IN A MOIST-AIR ENVIRONMENT
(1994-11-01)
YEN, AJ
;
LEE, YS
;
TSENG, TY
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Multilayer-chip varistors mere prepared using the ZnO-glass system by applying tape casting technology. The effect of processing conditions on the multilayer ceramic microstructure and electrical properties mas studied. The location, size, and density of the pores within the multilayer structure were examined by scanning electron microscopy and the displacement method using distilled mater. The experimental results showed that the electrical properties of a multilayer-chip varistor could be influenced substantially by the porosities associated with environmental moisture in the range approximate to 15%-95% relative humidity at 25 degrees C. Such an effect can cause substantial current leakage as well as the separation of the I-V curves into four regions, i.e., prebreakdown, linear, breakdown, and upturn. A proposed pore model and equivalent circuit for the multilayer-chip ZnO varistors have been simulated with a commercial varistor and a serial resistance to demonstrate the observed I-V phenomena.
RECOVERY OF THE SOLITON SELF-FREQUENCY SHIFT BY OPTICAL-PHASE CONJUGATION
(1994-11-01)
CHI, S
;
WEN, SF
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光電工程學系
;
Department of Photonics
The recovery of the self-frequency shift effect on a soliton by optical phase conjugation is investigated. It is proved that, without third-order dispersion and fiber loss, the soliton self-frequency shift can be completely recovered. The recoveries for a fundamental soliton and a second-order soliton in the presence of third-order dispersion and of fiber loss, which is compensated by the distributed erbium-doped fiber amplifiers, are numerically studied.
TESTING THE DYNAMIC FULL ACCESS PROPERTY OF A CLASS OF MULTISTAGE INTERCONNECTION NETWORKS
(1994-11-01)
LEE, TH
;
CHOU, JJ
;
電控工程研究所
;
電信工程研究所
;
Institute of Electrical and Control Engineering
A banyan network and its topologically equivalent ones have recently been adopted as the interconnection networks in a multiprocessor system. Often a multiprocessor system is reconfigured when the banyan network becomes faulty. It is possible to avoid a complicated reconfiguration process as long as the faulty banyan network still possesses the dynamic full access (DFA) property. In this short note, we determine a necessary and sufficient condition for a faulty banyan network to possess the DFA property and design a testing procedure based on the condition. The testing procedure can be used to decompose a faulty banyan network into subsystems possessing the DFA property. We also evaluate the probability that a banyan network loses the DPA property, given the number of faulty switching elements. It is found that as long as faults do not occur in switching elements located in the first and the last stages, this probability is very small, even when there are quite a few faulty switching elements.
NUMERICAL COMPUTATIONS OF INTEGRALS OVER PATHS ON RIEMANN SURFACES OF GENUS-N
(1994-11-01)
LEE, JE
;
交大名義發表
;
應用數學系
;
National Chiao Tung University
;
Department of Applied Mathematics
This paper is a continuation of work by Forest and Lee 1,2 . In 1,2 it was proved that the function theory of periodic soliton solutions occurs on the Riemann surfaces R of genus N, where the integrals over paths on R play the most fundamental role. In this paper a numerical method is developed to evaluate these integrals. Precisely, the aim is to develop a computational code for integrals of the form integral(gamma) f(z)dz/R(z), or integral(gamma) f(z)R(z)dz, where f(z) is any single-valued analytic function on the complex plane C, and R(z) is a two-valued function on C of the form GRAPHICS where {z(0)(k), 1 less than or equal to k less than or equal to 2N + delta} are distinct complex numbers which play the role of the branch points of the Riemann surface R = {(z, R(z))} of genus N - 1 + delta. The integral path gamma is continuous on R. The numerical code is developed in ''Mathematica'' 3 .
DESIGN FOR MANUFACTURING THE ELASTIC PIVOTS WITH SPECIAL REFERENCE TO MANUFACTURING ERROR
(1994-11-01)
YANG, YN
;
CHENG, WH
;
LEE, AC
;
交大名義發表
;
機械工程學系
The stiffness of an elastic pivot, a kind of torsional hinge, must usually be small in the direction of axial rotation and high in all other directions. In some applications, such as the gimbal suspension of the tuned gyroscope in an inertial guidance system, the size of the elastic pivot is small, and consequently the pivot becomes very sensitive to machining error. In this paper, we model the machining error in terms of the position error and roll-pitch-yaw angle error of the electrode in the electric discharge machining process. In the corresponding design problem, we recommend design procedures that allow a compromise between product performance and manufacturability. This paper introduces different types of elastic pivots, analyzes machining error due to machining inaccuracy, and treats the shape optimization. We believe that the design-for-manufacturability methodology developed here will be helpful in the design of many other precision mechanical components.
RAMAN-SCATTERING OF FEXRU1-XS2 MIXED-CRYSTALS
(1994-11-01)
HWANG, ST
;
LEE, MC
;
TSAY, MY
;
HUANG, YS
;
電子物理學系
Raman scattering of mixed dichalcogenides FexRu1-xS2 has been measured for the first time. Our results show not only resonant enhancements that are related to the inter-electronic-band transitions, but also mixed mode behavior with strong coupling between neighboring Raman active modes. Good interpretation is obtained by the spa tial correlation model.
A NOVEL DIAC-LIKE SWITCH USING DOUBLE TRIANGULAR BARRIERS
(1994-11-01)
YARN, KF
;
WANG, YH
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CHANG, CY
;
電控工程研究所
;
Institute of Electrical and Control Engineering
In this study, a new diac-like switch using GaAs double triangular barrier structures (DTBS) prepared by molecular beam epitaxy (MBE) has been fabricated and demonstrated. Unique bidirectional current-voltage (I-V) characteristics between 300 and 77 K were realized for the first time. Large on/off voltage differences and control efficiency were observed in both directions. Based on I-V measurements, the operation mechanism of the diac-like switch was analyzed and is discussed in detail using an equivalent circuit approach. A temperature-dependent effect on the switching voltage, V(S), and holding voltage, V(H), was also investigated.
ON THE COMPUTATION OF THE NONCENTRAL BETA-DISTRIBUTION
(1994-11-01)
DING, CG
;
管理科學系
;
Department of Management Science
Two recurrence formulas for computing the noncentral beta distribution function and the density are proposed. The computations can be carried to any specified accuracy using the error bounds obtained. Corresponding algorithms are provided in a step-by-step form. A close relationship between the formulas allows joint evaluation of the distribution function and the density. The noncentral beta quantile can then be efficiently computed using Newton's method. Its algorithm is also given in a step-by-step form.
SUPERTHIN O/N/O STACKED DIELECTRICS FORMED BY OXIDIZING THIN NITRIDES IN LOW-PRESSURE OXYGEN FOR HIGH-DENSITY MEMORY DEVICES
(1994-11-01)
SU, HP
;
LIU, HW
;
HONG, G
;
CHENG, HC
;
電子工程學系及電子研究所
High-performance superthin oxide/nitride/oxide (O/N/O) stacked dielectrics have been successfully achieved by oxidizing thin nitride films in low-pressure dry-oxygen at 850-degrees-C for 30 min. Since the nitrides exhibit a better oxidation resistance to the low-pressure dry-oxygen than to the atmospheric-pressure dry-oxygen and wet-oxygen, the low pressure oxidation obtains a thinner oxidized nitride for the high-density dynamic-random-access-memories (DRAM's) and metal-oxide-nitride-oxide-semiconductor (MONO'S) memory devices. In addition, this dielectric possesses low leakage current and excellent time-dependent-dielectric-breakdown (TDDB) characteristics. Therefore, this novel recipe is promising for future ULSI technology.