Browsing by Issue Date, starting with "1993-08-15"

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THE ENHANCED STARK EFFECTS OF COUPLED QUANTUM-WELLS AND THEIR APPLICATION TO TUNABLE IR PHOTODETECTORS
(1993-08-15)
HUANG, YM
;
LIEN, CH
;
LEI, TF
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
A tunable asymmetric coupled quantum well far-infrared photodetector is proposed in this paper. The basic asymmetric coupled quantum wells are composed of two quantum wells separated by a thin barrier. In this way, the electron in each well interacts strongly with other electrons to achieve a large Stark tuning effect. The eigenenergies and the wave functions of the quantum-well structures are solved by the self-consistent method, and the effect of the exchange interaction on the ground-state subband has also been taken into account. The absorption coefficient is evaluated by the density-of-states formalism. Based on theoretical calculations, tuning ranges from 8.2 to 11.3 mum and 7.8 to 10.5 mum are predicted for the proposed asymmetric coupled-quantum-well structure and high-low coupled-quantum-well structure, respectively. This tuning capability is achieved by varying the applied electric field in the 20-90-kV/cm range.
CHARACTERISTICS OF LOW-TEMPERATURE AND LOW-ENERGY PLASMA-ENHANCED CHEMICAL-VAPOR-DEPOSITED SIO2
(1993-08-15)
HSIEH, SW
;
CHANG, CY
;
HSU, SC
;
電子物理學系
;
電控工程研究所
Deposition of high quality silicon dioxides was obtained at low temperatures by a specially designed plasma chemical vapor deposition (PECVD) system. The system employed a long quartz tube as a reactor and a set of three vertically standing plates for glow discharge. The deposited oxide, which employed a large amount of helium (He) to dilute silane (SiH4) and nitrous oxide (N2O) reactants, was observed to possess excellent qualities, as compared to those of thermally grown oxides. The chemical composition used for obtaining electrical integrities of the PECVD oxides was investigated. Additionally, the effects of post-metallization annealing on the oxides were investigated in detail. Oxides deposited at a substrate temperature of 250-degrees-C were observed to possess a low interface trap state density (D(it)) of only 3 X 10(10) cm-2 eV-1 and low total trapped charge density (Q(total)) of 5.8 X 10(16) cm-3. Those, however, which were deposited at 350-degrees-C, have more stable electrical characteristics under current/voltage bias-temperature stress, but their D(it) and Q(total) are around 2 X 10(11) cm-2 eV-1 and 3.4 X 10(16) cm-3, respectively. An atom-bonding model was proposed in this present work, according to physical, chemical, and electrical analyses in accounting for phenomena of charge-trapping and also in upgrading the electrical integrity of the deposited oxides. The applicability of these low-temperature oxides toward fabricating hydrogenated amorphous-silicon thin film transistor (a-Si:H TFT's) was investigated. Adequate electrical performances of the TFT's with a high on/off current ratio of more than 10(6) and high field effect mobility (mu(FET)) Of around 0.6 cm2/V s were obtained.
MANIPULATING MULTIPLE STACKS WITH ORDERED-HEAP
(1993-08-15)
CHIEN, BC
;
YANG, WP
;
CHEN, RJ
;
資訊工程學系
;
Department of Computer Science
A new method for manipulating multiple stacks based on dynamic data structure is proposed in this paper. A simple data structure called ordered-heap is developed, in which nodes are preserved as a heap, and kept inorder traversal sequence remains unchanged. By employing ordered-heap to a multiple-stacks environment, it is easy and efficient to simultaneously handle several variable-size stacks in a sequential memory area. Our experiments show that not only the total number of item movements in the proposed method is much smaller than in the previous methods, but also the overhead for maintaining data structure in the proposed method is kept within a reasonable range.
ELECTRICAL AND MICROSTRUCTURAL CHARACTERISTICS OF TI CONTACTS ON (001)SI
(1993-08-15)
LIAUH, HR
;
CHEN, MC
;
CHEN, JF
;
CHEN, LJ
;
電子工程學系及電子研究所
An investigation of the electrical and microstructural characteristics of the Ti contact on silicon has been carried out. The presence of As in Ti/n+-Si samples was found to retard the formation of polycrystalline silicide (p-silicide) compared with that in Ti/p+-Si samples with BF2+ implantation. Amorphous interlayers (a-interlayers) were found to be present in both Ti/n-Si and Ti/p-Si samples annealed at temperatures of and lower than 450-degrees-C. Although the Schottky barrier heights (SBH's) vary for about 0.05-0.08 eV for samples annealed over a temperature range from room temperature to 900-degrees-C, SBH's at the a-interlayer/n-Si and a-interlayer/p-Si were measured to be about 0.52-0.54 and 0.59-0.57 eV, respectively. The specific contact resistance (p(c)) in the Ti/n+-Si system was measured to be the lowest with a value of 1.4 X 10(-7) OMEGA cm2 when the a interlayer is present. In Ti/p+-Si system, the minimum rho(c) is about 3 X 10(-7) OMEGA cm2. The variation in contact resistance with annealing temperature for both Ti/n+-Si and Ti/p+-Si samples is correlated to the change in dopant concentration beneath the contacts as well as microstructures. In the temperature regime where the a interlayer is in contact with the silicon substrate, the junction diode leakage current densities (J(leak's)) are considerably lower than those in samples annealed at higher temperatures. The J(leak) at - 6 V reverse bias is lower than 1 nA/cm2. The breakdown voltage is about 14 V (16 V) for the n+/p (p+/n) junction. The thickness of consumed Si is less in samples annealed at low temperature, and the a-interlayer/Si or p-silicide/Si interface is accordingly farther away from the junction as well as the end-of-range defects. The interface of p-silicide/Si is rougher than that of a-interlayer/Si. In addition, the roughness of the p-silicide/Si interface increases with annealing temperature. For both p+/n and n+/p junctions annealed at 900-degrees-C, rough p-silicide/Si interfaces are thought to lead to spiking and increase the leakage currents.
OPTICAL-CONSTANTS MODEL FOR SEMICONDUCTORS AND INSULATORS
(1993-08-15)
CHEN, YF
;
KWEI, CM
;
TUNG, CJ
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
The refractive index and the extinction coefficient, i.e., the real and imaginary parts of the complex index of refraction, for semiconductors and insulators are derived as a function of photon energy. These derivations apply f-sum rules and symmetry relations to critical-point transitions from the valence band to the conduction band. Comparison with measured optical data reveals that present formulations are valid over a wide range of photon energies immediately above the band gap to the first ionization threshold for inner shells. The present work shows an improvement and extension over the theory of Forouhi and Bloomer, which applies for a narrow range of photon energies above the absorption edge.
ELECTRON INELASTIC MEAN FREE PATHS FOR PLASMON EXCITATIONS AND INTERBAND-TRANSITIONS
(1993-08-20)
KWEI, CM
;
CHEN, YF
;
TUNG, CJ
;
WANG, JP
;
電子工程學系及電子研究所
Both plasmon excitations and interband transitions are important in the response of valence bands to fast electrons. An extended Drude dielectric function was established to describe such a response in solids of complex band structures. Parameters in this function were determined by a fit of the imaginary part of the function to experimental optical data. The real part of the dielectric function and the energy-loss function were also checked with experimental data to confirm critical-point energies in the interband transitions and plasmon energies in the collective excitations. In addition, sum-rules about the imaginary part of the dielectric function and the energy-loss function, respectively, were applied to assure the accuracy of these functions. Electron inelastic mean free paths in several solids were calculated and compared to available experimental and theoretical data.
未去榆林心事
(1993-08-21)
管管
DEPOSITION OF THIN-FILMS FROM (TBUN)2MO(NHTBU)2
(1993-08-22)
CHIU, HT
;
HO, WY
;
應用化學系
;
Department of Applied Chemistry
GENERATING THE BEST K-SEQUENCES IN RELOCATION PROBLEMS
(1993-08-27)
LIN, BMT
;
TSENG, SS
;
資訊科學與工程研究所
;
Institute of Computer Science and Engineering
There is a set J of h jobs to be processed. For every i, job J(i) demands n(i) units of resources and returns a(i) units after completion. The problem is to find the best K schedules whose resource requirements are minimum among all h! ones. In this paper, we present some important structural properties and then propose an O(h log h + hK log K) time algorithm, which runs in polynomial time if K is fixed.
THE PROCESS LIMITATION FOR FORMING TI SILICIDED SHALLOW JUNCTION BY BF(2)+ IMPLANTATION INTO THIN POLYCRYSTALLINE SI FILMS AND SUBSEQUENT TI SILICIDATION
(1993-08-30)
JUANG, MH
;
LIN, CT
;
JAN, ST
;
CHENG, HC
;
電控工程研究所
Excellent shallow p+n junctions have been formed by implanting BF2+ ions into thin polycrystalline Si films and subsequent annealing; these junctions which show a leakage of 1 nA/cm2 and a junction depth of about 0.05 mum. An anomalous boron diffusion occurs when subsequent silicidation is carried out. Silicidation using 300-angstrom Ti just slightly affected the junction profile. However, the junction is considerably deepened for 600-angstrom Ti silicidation, yielding a resulting depth of about 0.11 mum. The large boron redistribution is attributed to the point defects induced by silicidation. Hence, proper silicide thickness should be chosen to retain the junction profile as well as to reduce the parasitic source/drain resistance.
CHARGE LOSS DUE TO AC PROGRAM DISTURBANCE STRESSES IN EPROMS
(1993-09-01)
LIN, JK
;
CHANG, CY
;
WANG, TH
;
HUANG, HS
;
CHEN, KL
Charge loss in interpolyoxide erasable programmable read-only memories (EPROMs) due to program disturbance by alternating current pulses applied to the drain was studied for the first time. It was found that the charge loss due to ac stress is more severe than that due to dc stress. Experimental results reveal that the more positive the floating gate potential, the more severe is the drain ac disturbance observed. The main reason for the charge loss is the displacement current which agitates the charges in the floating gate, creating a leakage path from the floating gate to the drain, in which the drain-to-floating-gate overlapping capacitance C(fd) plays an important role. The drain dc stresses of interpolyoxide/nitride/oxide (ONO) EPROMs were also measured under different bias conditions and temperatures. The data show that higher dc electric field of the floating gate to the drain results in larger V(th) shift, which can be accelerated by elevated temperature. In addition, the control gate ac stress-enhanced drain dc disturbance was also measured. We proposed that the dc drain stress is applied during the ac gate stress, which results in a heating effect. The results support the concept of dielectric ac heating.
BINARY PARTITION ALGORITHMS AND VLSI ARCHITECTURES FOR MEDIAN AND RANK ORDER FILTERING
(1993-09-01)
LEE, CL
;
JEN, CW
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
A class of selection algorithms by binary partition is very efficient for median and rank order filtering. A unified discussion of these algorithms is presented. Binary partition algorithms have better time-area complexity than sorting methods. Counting, firing, and updating are three basic steps. A generic structure is proposed to realize these algorithms. They can be implemented by simple and regular modules in VLSI.
NONPERTURBATIVE DEFORMATION OF CONFORMAL FIELD-THEORY AND SPONTANEOUSLY BROKEN INTER MASS LEVEL SYMMETRIES IN STRING THEORY
(1993-09-01)
LEE, JC
;
交大名義發表
;
電子物理學系
;
National Chiao Tung University
;
Department of Electrophysics
We study the deformation of conformal field theory without leaving the fixed points. It is found that an infinite number of higher spin background fields are needed to cancel the q-number anomalies when one goes beyond first order weak field calculation. This phenomenon can be interpreted in string theory as spontaneously broken symmetries between particles with different masses.
COMMENTS ON A NEURAL-NETWORK APPROACH TO MVDR BEAMFORMING PROBLEM - REPLY
(1993-09-01)
CHANG, PR
;
YANG, WH
;
CHAN, KK
;
交大名義發表
;
電信工程研究所
REGULAR ENUMERATION OF GRID POINTS IN A CONVEX POLYGON
(1993-09-01)
Lee, Hsuan-Shih
;
Chang, Ruei Chuan
;
資訊工程學系
;
Department of Computer Science
In this paper we present an efficient algorithm for enumerating all the grid points in a convex polygon, where the enumeration is done by scanning the grid points with a set of parallel grid lines. Given a convex n-gon, enumeration can be done in O(K + + log min{root l/omega, l}) time, where K is the number of the grid points reported, l is the diameter of the polygon and omega is the length of the shorter sides of the rectangle enclosing the polygon with longer sides parallel to the line segment connecting the diametral pair of the polygon. We also show that the ratio of the number of the scanned grid lines to the minimal is less than some constant.
A NEW APPROACH TO DETERMINE THE DRAIN-AND-SOURCE SERIES RESISTANCE OF LDD MOSFETS
(1993-09-01)
CHUNG, SSS
;
LEE, JS
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
A new method for determining the intrinsic drain-and-source series resistance and the effective channel length of LDD MOSFET's is proposed. The method is based on the experimentally measured device I-V characteristics and a new parameter extraction procedure. A consistent set of the effective channel length and the gate-voltage-dependent drain-and-source series resistance was thus determined. The comparison between the measured and experimental drain current characteristics shows excellent agreement using the present model values.
AN OPTIMUM PARTITION FOR INVERTING A NONSINGULAR MATRIX
(1993-09-01)
LUO, JC
;
交大名義發表
;
土木工程學系
;
National Chiao Tung University
;
Department of Civil Engineering
A new strategy for inverting a nonsingular matrix is evaluated in this paper. The essential concept of this strategy is to partition a nonsingular matrix into blocks, then to apply the author's decomposition to the block-based procedure. Since different partitions require different costs, finding an economical partition is necessary. This paper studies the optimum partition so that the complexity for the inverse of a nonsingular matrix may be significantly reduced.
ELECTRONIC-ENERGY SPECTRUM IN AN ASYMMETRIC QUANTUM-WELL WITH A CROSSED MAGNETIC AND ELECTRIC-FIELD
(1993-09-01)
WANG, CS
;
CHUU, DS
;
電子物理學系
;
電控工程研究所
;
Department of Electrophysics
The energy spectra of an electron in an asymmetric quantum well within an in-plane magnetic field and an electric field perpendicular to the barrier interfaces are exactly derived and the numerical results are calculated by iteration. The ground and excited states are calculated for various asymmetric potential barriers, well widths and electric fields. Major different characteristics of energy spectra between wide and narrow wells are discussed. The behaviors of a bulk Landau level in the well region of a larger well width and the elevation of the ground state in a smaller well width are explained. The density distribution of electrons in a large well region is strongly affected by the barrier ratio and the electric field in the growth direction.
TYPE SYNTHESIS OF VEHICLE PLANAR SUSPENSION MECHANISM USING GRAPH-THEORY
(1993-09-01)
LIU, TS
;
CHOU, CC
;
交大名義發表
;
機械工程學系
;
National Chiao Tung University
This paper presents a graph theory-based approach to optimum type synthesis of vehicle suspension mechanisms using an expert system. Kinematic chain isomorphism is identified, using an extended degree method to facilitate the enumeration of kinematic structures. Rules representing design criteria and the flow value theory based on energy loss calculation are incorporated in the rule base to evaluate and select mechanisms among those that are enumerated in the database. Statistical variance calculation serves to complement the flow value theory. A new method called the extended flow value method is devised for isomorphism checking of labeled graphs. In the spirit of increasing emphasis on the riding quality of vehicles, several novel suspension configurations are created to ensure maintenance ease and vibration damping efficiency.
COMPUTER-BASED ENVIRONMENT FOR WASTE-WATER TREATMENT-PLANT DESIGN
(1993-09-01)
KAO, JJ
;
BRILL, ED
;
PFEFFER, JT
;
GESELBRACHT, JJ
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環境工程研究所
A prototype computer-based design environment was developed to facilitate wastewater treatment plant design tasks. The design environment includes several mathematical techniques, interactive graphic displays, and user-friendly interfaces. The mathematical techniques are mass and water balances for an analysis program for plant design and a rule-based system for evaluating the likelihood of sludge bulking. A processor is also used to check a given design using existing design standards. The interactive graphic displays and the user interfaces are intended to provide a user-friendly environment for manipulating data, models, and solutions. Sensitivity analyses can be performed for models as well as parameters. The features of the computer-based system are described, and suggestion for extensions are given.