Browsing by Issue Date, starting with "1994-03-21"

Now showing 1 - 20 of 88369

STRONG ACCUMULATION OF AS PRECIPITATES IN LOW-TEMPERATURE INGAAS QUANTUM-WELLS GROWN BY MOLECULAR-BEAM EPITAXY
(1994-03-21)
CHENG, TM
;
CHIN, A
;
CHANG, CY
;
HUANG, MF
;
HSIEH, KY
Low temperature InGaAs strained quantum wells have been grown by molecular beam epitaxy and annealed at 600-900-degrees-C for 10 min. For an optimized annealing condition, arsenic precipitates can be successfully confined in the InGaAs wells and completely depleted in the GaAs barriers. The strong accumulation of As precipitates shows that the phenomena are not due to the strain effect but may be explained by the difference of interfacial energy between precipitate and matrix. The ability to control the As precipitates into two-dimensional quantum wells in LT materials has unique applications in a wide variety of devices.
A GLOBAL APPROACH FOR GENERAL 0-1 FRACTIONAL-PROGRAMMING
(1994-03-24)
LI, HL
;
交大名義發表
;
資訊管理與財務金融系註：原資管所+財金所
;
National Chiao Tung University
;
Department of Information Management and Finance
Current methods of general 0-1 fractional programming (G-FP) can only find the local optimum. This paper proposes a new method of solving G-FP problems by a mixed 0-1 linear program to obtain a global optimum. Given a mixed 0-1 polynomial term xy where x is a 0-1 variable and 0 < y less-than-or-equal-to 1, we develop a theorem to transfer the xy term into a set of mixed 0-1 linear inequalities. Based on this theorem, a G-FP problem can be solved by a branch-and-bound method to obtain the global solution.
管管的詩畫世界
(1994-03-24)
管管
管管的詩畫世界
(1994-03-24)
管管
管管的詩畫世界
(1994-03-24)
管管
管管的詩畫世界
(1994-03-24)
管管
A CONSTRAINT VARIATION TREATMENT FOR ROTATING NUCLEAR INTRINSIC STATES IN THE LABORATORY SYSTEM
(1994-03-28)
LIN, L
;
交大名義發表
;
電子物理學系
;
National Chiao Tung University
;
Department of Electrophysics
The cranking model describes nuclear rotation in the rotating frame. However, the physical experiments are performed in the laboratory system. In this article, a constraint variation treatment is suggested to generate a set of single particle orbitals with rotational characteristics. By using this set of basis vectors, we can obtain a rotating nuclear intrinsic state which is observed in the laboratory system.
COMPLEX-VALUED NEURAL-NETWORK FOR DIRECTION-OF-ARRIVAL ESTIMATION
(1994-03-31)
YANG, WH
;
CHAN, KK
;
CHANG, PR
;
交大名義發表
;
電信工程研究所
A complex-valued neural network for the implementation of a direction of arrival (DoA) estimator is presented. The network is based on the linear prediction method, with data processed fully in the complex domain. Simulation results are given to demonstrate the effectiveness of the network performances.
QUANTIZATION-ERROR CURVE - A MEASURE OF SIMILARITY BETWEEN REQUANTISED IMAGES
(1994-03-31)
CHU, CH
;
HSUEH, YC
;
資訊工程學系
;
Department of Computer Science
A new similarity measure between a digital image and its quantised version is presented. By calculating the quantisation error on each of a sequence of subdomains, we can obtain a quantisation error curve as a similarity measure. This measure outperforms the commonly used measure for estimating the similarity between requantised images.
BINDING-ENERGIES OF D- ION IN GAAS QUANTUM-WELL
(1994-04-01)
CHANG, YH
;
YEH, JJ
;
SHEU, YM
;
WANG, CC
;
CHEN, TC
Magnetic field dependent binding energies of the D- ion in the center of a 210 angstrom GaAs quantum well are determined by temperature magneto-transport measurments. The binding energies increase from 2.1 meV at 2T to 4 meV at 8T, and are consistently higher than the transition energies ootained from magneto-optical measurements performed on the same sample. We conclude from these data that in the magneto-optical measurement the observed transitions are between ground and excited D- states.
NANOMETER THICK SI/SIGE STRAINED-LAYER SUPERLATTICES GROWN BY AN ULTRAHIGH-VACUUM CHEMICAL-VAPOR-DEPOSITION TECHNIQUE
(1994-04-01)
CHANG, TC
;
CHANG, CY
;
JUNG, TG
;
TSAI, WC
;
WANG, PJ
High quality Si/Si1-xGex superlattices having layers as thin as 1.5 nm have been grown by an ultrahigh vacuum/chemical vapor deposition system. High-resolution double-crystal x-ray diffraction, and conventional and high-resolution cross-sectional transmission electron microscopy were used to evaluate the crystalline quality of these superlattices. A dynamical x-ray simulation program was employed to analyze the experimental rocking curves. Excellent matches between experimental rocking curves and simulated ones were obtained for all superlattices with various periodicity. A cross-sectional transmission electron micrograph of an 80 period Si(4.2 nm)/Si0.878Ge0.122 (1.5 nm) superlattice, in which each individual layers was clearly resolved, demonstrated the capability of this growth technique for nanometer thick layer deposition.
CHARACTERIZATION OF SI/SIGE STRAINED-LAYER SUPERLATTICES GROWN BY AN ULTRAHIGH-VACUUM CHEMICAL-VAPOR-DEPOSITION TECHNIQUE
(1994-04-01)
CHANG, TC
;
CHANG, CY
;
JUNG, TG
;
TSAI, WC
;
HUANG, GW
High-resolution double-crystal X-ray diffraction and cross-sectional transmission electron microscopy were used to characterize the Si/SiGe strained-layer superlattices grown by the ultrahigh vacuum/chemical vapor deposition (UHV/CVD) system. A dynamical X-ray simulation was employed to analyze the experimental rocking curves. Good matches between the experimental rocking curves and the simulated ones demonstrate that the high quality Si/SiGe strained-layer superlattices with abrupt interface and excellent thickness and composition uniformity have been achieved. Thickness uniformity was further confirmed by the cross-sectional transmission electron microscopy. In addition, high-resolution double-crystal X-ray diffraction was proven to be a powerful technique for determining the doping level and the thickness of heavily doped contact layer in Si/SiGe device structures prior to further processing. Good wafer-to-wafer uniformity can be simultaneously achieved by the UHV/CVD technique; as a result, the UHV/CVD technique is readily applicable to manufacturing.
ANALYSIS OF A CUTOFF PRIORITY CELLULAR RADIO SYSTEM WITH FINITE QUEUING AND RENEGING/DROPPING
(1994-04-01)
CHANG, CJ
;
SU, TT
;
CHIANG, YY
;
電信工程研究所
;
電信研究中心
Queueing of new or handoff calls can minimize blocking probabilities or increase total carried traffic. This paper investigates a new cutoff priority cellular radio system that allows Smite queueing of both new and handoff calls. We consider the reneging from the system of queued new calls due to caller impatience and the dropping of queued handoff calls by the system as they move out of a handoff area before being accomplished successfully. We use signal-flow graphs and Mason's formula to obtain the blocking probabilities of new and handoff calls and the average waiting times. Moreover, an optimal cutoff parameter and appropriate queue sizes for new and handoff calls are numerically determined so that a proposed overall blocking probability is minimized.
LOW-TEMPERATURE-PROCESSED POLY-SI THIN-FILM TRANSISTORS USING SOLID-PHASE-CRYSTALLIZED AND LIQUID-PHASE-DEPOSITED GATE OXIDE
(1994-04-01)
YEH, CF
;
CHEN, CL
;
YANG, YC
;
LIN, SS
;
YANG, TZ
Poly-Si thin-film transistor (TFT) devices using solid-phase-crystallized and liquid-phase-deposited gate oxide are, for the first time, realized by low-temperature processes (LTP) (<625-degrees-C) for future LCDs and 3-D integrated circuits. The method of liquid-phase deposition of SiO2 (LPD-SiO2) is described. The physical, chemical and electrical properties of the new dielectric layer are clarified. The TFT (W/L = 200 mum/10 mum) having an on-off current ratio of 10(6) at V(D) = 5 V, a field-effect mobility of 15 cm2/V.s at V(D) = 0.1 V, a threshold voltage of 5.6 V, and a subthreshold swing of 1.6 V/decade, exhibits sufficient performance for pixel transistors. The field-effect mobility is strongly dependent on channel length. Effective passivation of defects by plasma hydrogenation will be very essential to achieve higher performance.
MULTICOMPONENT ION-EXCHANGE COLUMN DYNAMICS
(1994-04-01)
TAN, HKS
;
SPINNER, IH
;
應用化學系
;
Department of Applied Chemistry
Simple model equations which consider different rate control mechanisms are formulated for fixed bed multicomponent ion exchange processes. Efficient and accurate numerical methods are developed for solving these equations for liquid phase, solid phase or combined phase control. The algorithms are applicable to both ion exchange and liquid adsorption and are shown to be extendable to a general form of isotherms. The accuracy of the numerical algorithm is evidenced by the fact that the asymptotic limiting equilibrium solutions are closely approached as the dimensionless length parameter is increased, regardless of the rate control mechanism. Numerical examples for ion exchange applications are presented. These examples included multicomponent elution and purification problems. The effect of mass transfer resistance was also examined. Other examples examine the validity of a model reduction assumption and the comparison of equilibrium theory with the results obtained using the present finite mass transfer rate model.
BORON-DOPED DIAMOND FILMS USING TRIMETHYLBORATE AS A DOPANT SOURCE IN METHANE CARBON-DIOXIDE GAS-MIXTURES
(1994-04-01)
CHEN, CF
;
CHEN, SH
;
HONG, TM
;
WANG, TC
;
材料科學與工程學系
The effects of boron concentration in the gas phase on the morphological features and cathodoluminescence (CL) of polycrystalline diamond films were investigated. The diamond films were prepared on p-type Si(100) substrates by microwave plasma chemical vapour deposition. Trimethylborate vapour was introduced to the CH4-CO2 gas mixture as a dopant source. Secondary ion mass spectroscopy (SIMS), Raman and CL spectroscopy and scanning electron microscopy analysis were performed on the films. The depth profile of SIMS showed that boron was uniformly doped into the diamond film even at a depth of 6 mum. Boron was found to have a significant effect on both the morphology and cathodoluminescence of the deposited films. The surface morphology changed from well-defined facets to ball-like features with increasing gas phase dopant concentration. To obtain doped diamond films of good quality, it is necessary to lower the carbon concentration by decreasing the flow rate of CH4 during the deposition process. The cathodoluminescence of diamond films was investigated in the range 1.8-4.0 eV. The emission peak intensity of CL spectra at 2.3-2.4 eV was found to increase with increasing dopant concentration in the gas phase. The luminescence is explained by donor-acceptor pair recombination, where the acceptor is substitutional boron. This result indicates that the boron atoms can be successfully doped into substitutional sites of the diamond structure.
ENHANCEMENT OF OXIDE BREAK-UP BY IMPLANTATION OF FLUORINE IN POLY-SI EMITTER CONTACTED P-+-N SHALLOW JUNCTION FORMATION
(1994-04-01)
WU, SL
;
LEE, CL
;
LEI, TF
;
CHEN, CF
;
CHEN, LJ
In this study, it is demonstrated that the incorporation of fluorine can enhance poly-Si/Si interfacial oxide break-up in the poly-Si emitter contacted p+-n shallow junction formation. The annealing temperature for breaking up the poly-Si/Si interfacial oxide has been found to be as low as 900-degrees-C. As a result, the junction depth of the BF2-implanted device is much larger than that of the boron-implanted device.
OPTIMAL MULTIPROCESSOR TASK-SCHEDULING USING DOMINANCE AND EQUIVALENCE-RELATIONS
(1994-04-01)
CHOU, HC
;
CHUNG, CP
;
資訊科學與工程研究所
;
Institute of Computer Science and Engineering
We propose an optimization scheme for unit-execution-time task scheduling on multiprocessors. In this scheme, dominance, semi-dominance, equivalence and semi-equivalence relations between tasks are first defined. The solution tree technique is adopted to keep track of the unfinished sub-schedules. We prove that when certain conditions are satisfied, a sub-schedule need not be explored further, since it cannot lead to a schedule better than some others. An algorithm that avoids generating such non-optimal schedules is presented. Then we conduct experiments to show the promise of our scheme in reducing solution space. Another advantage of this scheme is its extensibility. This scheme can easily be applied to other scheduling problems by simply adding additional constraints to the original definitions of the dominance, semi-dominance, equivalence and semi-equivalence relations.
IMPROVED QUANTITATIVE MEASURES OF ROBUSTNESS FOR MULTIVARIABLE SYSTEMS
(1994-04-01)
CHEN, HG
;
HAN, KW
;
電控工程研究所
;
Institute of Electrical and Control Engineering
Asymptotically stable linear systems subject to unstructured time varying perturbations are considered. Allowable perturbation bounds are obtained such that the perturbed systems remain stable. These bounds are derived iteratively by means of adjusting a sequence of Lyapunov matrices. In comparison with existing methods, less conservative quantitative measures of robustness are obtained.
COLLOCATED SENSOR ACTUATOR POSITIONING AND FEEDBACK DESIGN IN THE CONTROL OF FLEXIBLE STRUCTURE-SYSTEM
(1994-04-01)
LEE, AC
;
CHEN, ST
;
交大名義發表
;
機械工程學系
;
National Chiao Tung University
This paper presents a new control design method for the control of flexible systems that not only guarantees closed-loop asymptotic stability but also effectively suppresses vibration. This method allows integrated determination of actuator/sensor locations and feedback gain via minimization of an energy criterion, which is chosen as the integrated total energy stored in the system. The energy criterion is determined via an efficient solution of the Lyapunov equation and minimized with a quasi-Newton or recursive quadratic programming algorithm. The prerequisite for this optimal design method is that the controlled system be asymptotically stable. This study shows that when the controller structure is a collocated direct velocity feedback design with positive definite feedback gain, the number and placement of actuators/sensors are the only factors needed to determine necessary and sufficient conditions for ensuring closed-loop asymptotic stability. The application of this method to a simple flexible structure confirms the direct relationship between our optimization criterion and effectiveness in vibration suppression.