Browsing by Issue Date, starting with "1999-03-19"

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Thermal reactions of phosphine with Si(100): a combined photoemission and scanning-tunneling-microscopy study
(1999-03-19)
Lin, DS
;
Ku, TS
;
Sheu, TJ
;
物理研究所
;
Institute of Physics
This study investigates the adsorption and thermal decomposition of phosphine (PH3) on the Si(100)-(2 x 1) surface. The adsorption species, dissociation reactions, atomic ordering, and surface morphology of the phosphine/Si(100) surface at temperatures between 300 and 1060 K are examined by scanning tunneling microscopy (STM) and high-resolution core-level photoemission spectroscopy employing synchrotron radiation. The P 2p core level spectra clearly indicate that phosphine molecularly adsorbs at room temperature and partially dissociates into PH2 and H on a time scale of minutes at low (<0.2ML) coverages. An exposure of >15 Langmuirs (L, 1 Langmuir=10(-6) Torr s(-1)) of phosphine on the Si(100)-(2 x 1) surface at room temperature produces a saturated and disordered surface. The total amount of P on the saturated surface is ca 0.37 ML as calibrated by the P 2p photoemission intensity. Successive annealing of the saturated surface at higher temperatures converts PH, into PH,, converts PH, to P-P dimers, and causes the desorption of PH3. These processes become complete at similar to 700 K, and the resulting surface is a H/Si(LOD)-(2 x 1) surface interspersed with one-dimensional P-P islands. Desorption of hydrogen from that surface occurs at similar to 800 K, and is accompanied by partial displacement of P with Si atoms on the substrate. At 850 K, the Si(100) surface, interspersed with 0.22 ML of two-dimensional islands, is a random alloy of nominal 0.5 ML Si-P heterodimers and 0.5 ML Si-Si dimers. (C) 1999 Published by Elsevier Science B.V. All rights reserved.
Oxidation of dichlorvos with hydrogen peroxide using ferrous ion as catalyst
(1999-03-19)
Lu, MC
;
Chen, JN
;
Chang, CP
;
環境工程研究所
;
Institute of Environmental Engineering
This study examines how Fenton's reagent (Fe2+ and H2O2) decomposed dichlorvos insecticide. Results showed that dichlorvos decomposed in a two-stage reaction. The first stage is a Fe2+/H2O2 reaction in which dichlorvos swiftly decomposed. In the second stage, dichlorvos decomposed somewhat less rapidly, and it is a Fe3+/H2O2 reaction. The detection of ferrous ions also supports the theory of the two-stage reaction for the dichlorvos oxidation with Fenton's reagent. The dissolved oxygen of the solution decreased rapidly in the first stage reaction, but it slowly increased in the second stage with a zero-order kinetics. The Fenton system decomposed dichlorvos most rapidly when the initial pH in the solution is 3-4. In addition, increasing the concentration of hydrogen peroxide or ferrous ions can enhance the decomposition of dichlorvos. Consequently, the relationship of rate constant (k(obs)), [H2O2] and [Fe2+] at initial pH 3 is determined as k(obs) = 2.67 X 10(4)[H2O2](0.7)[Fe2+](1.2). (C) 1999 Elsevier Science B.V. All rights reserved.
Effects of age and gender on remote pointing performance and their design implications
(1999-03-20)
Hsu, SH
;
Huang, CC
;
Tsuang, YH
;
Sun, JS
;
工業工程與管理學系
The purpose of this research is to investigate the effects of age and sex on remote pointing movements. In addition, an attempt was made to incorporate possible age-related or sex differences into the design of a remote pointing user interface. The subjects were recruited from three age groups (elderly, middle-aged, and young) with equal number of both sexes. The participants were required to perform cursor positioning tasks using a remote pointing device. Their static hand stability and remote positioning time were recorded and analyzed. The remote positioning time was further separated into two components: initial submovement duration and adjustment submovement duration. The results reveal that age-related effects reduced the subjects' ability to perform remote pointing tasks and also maintained hand stability. However, sex differences had no significant effect on either performance. Moreover, the results also reveal that remote positioning movements for the young group were mostly completed in their initial submovement phase, while the elderly subjects spent most of their movement time on the fine adjustment phase. In light of the fact that different age groups exhibit different kinds of movement behavior patterns, suggestions for the design of signal sensitivity, target features, and display/control gain in remote pointing user interface were outlined.
A design approach to the multi-objective facility layout problem
(1999-03-20)
Chen, CW
;
Sha, DY
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
A new multi-objective heuristic algorithm for resolving the facility layout problem is presented in this paper. It incorporates qualitative and quantitative objectives and resolves the problem of inconsistent scales and different measurement units. We consider suboptimal solutions since optimal methods are computationally unfeasible to large layout problems. In this paper, we develop the dominant index (DI) and incorporate it in our heuristic algorithm to guarantee the quality of proposed solutions. Moreover, a new measure of solution quality, dominant probability (D-p), is offered to determine the probability that one layout is better than the others. Computational results show that our proposed heuristic algorithm is an efficient method for obtaining good-quality solutions.
好了
(1999-03-24)
管管
好了
(1999-03-24)
管管
Inter-protocol interleaving attacks on some authentication and key distribution protocols
(1999-03-26)
Tzeng, WG
;
Hu, CM
;
資訊工程學系
;
Department of Computer Science
We present a new attack, called the inter-protocol interleaving attack, on authentication and key distribution protocols. The attack enlightens us two things. The first is that when considering attacks against a protocol, we should consider not only the protocol itself, but also the interaction with other protocols. The second is about a warning of "not using the shared secret keys between a server and its clients in any other places" that appears in many security-related communication standards, such as CCITT X.509 and ISO 9798. Our attack provides a concrete example for showing that this warning is necessary. (C) 1999 Elsevier Science B.V. All rights reserved.
Preparation and epoxy curing of novel dicyclopentadiene-derived Mannich amines
(1999-03-28)
Tseng, FP
;
Chang, FC
;
Lin, SF
;
Lin, JJ
;
應用化學系
Phenol/dicyclopentadiene (DCPD) adducts were prepared from the BF3-catalyzed reaction of p-nonylphenol and dicyclopentadiene at molar ratios of 2 : 1 and 3 : 2. The phenol-terminating adducts were consequently reacted with diethylenetriamine and formaldehyde using Mannich reaction conditions. These products containing phenol, amine and tricyclodecane functionalities in the same molecule can be used as epoxy curing agents. The diethylenetriamine was add to the phenol via Mannich reaction at approximately 50% theoretical equivalent. The multiple N-H soups in amines and the O-H groups in phenols provide crosslinking sites for epoxy resins. The cured epoxy resins show improvement in tensile strength and elongation in comparison with those cured by the poly(oxypropylene) diamine (400 molecular weight) or diethylenetriamine. (C) 1999 John Wiley & Sons, Inc.
Characterizations of bipartite Steinhaus graphs
(1999-03-28)
Chang, GJ
;
DasGupta, B
;
Dymacek, WM
;
Furer, M
;
Koerlin, M
We characterize bipartite Steinhaus graphs in three ways by partitioning them into four classes and we describe the color sets for each of these classes. An interesting recursion had previously been given for the number of bipartite Steinhaus graphs and we give two fascinating closed forms for this recursion. Also, we exhibit a lower bound, which is achieved infinitely often, for the number of bipartite Steinhaus graphs. (C) 1999 Elsevier Science B.V. All rights reserved.
Transmission properties of electrons in a T-type opened quantum waveguide with inhomogeneous magnetic fields
(1999-03-30)
Chen, K
;
Gu, BY
;
Lin, YK
;
Chuu, DS
;
電子物理學系
We calculate the quantum-mechanical transmission of electrons in a T-shaped opened quantum waveguide (TOQW) subjected to an inhomogeneous magnetic field perpendicular to the TOQW plane with the use of the mode-matching technique. An electron incident through one branch of the waveguide can travel into the other two channels in the quantum ballistic regime. We find that transmission coefficients in two channels exhibit quite difference from each other and depend sensitively on geometric parameters and magnetic configurations. Sharp peaks with unity amplitude and deep dips are observed in transmission spectrum as a function of the Fermi energy of the incident electrons at some high fields. We also study the variation of transmission with magnetic field and find that the transmission exhibits various patterns such as step drop, deep dips, wide valley, large oscillations, or without any structure, sensitively depending on the incident electron energy and magnetic confinement configurations. It is expected that by applying inhomogeneous magnetic fields to the TOQW with appropriate magnetic configuration one may provide an available way to control transmission property of the TOQW to match practical requirements in devices.
Time-resolved photoluminescence study of InGaAs/GaAs quantum wells on (111)B GaAs substrates
(1999-04-01)
Tsai, FY
;
Lee, CP
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Shen, JX
;
Oka, Y
;
Cheng, HH
The exciton dynamics in In0.15Ga0.85As/GaAs quantum wells grown on (111)B and (100)GaAs substrates are studied by the time-resolved photoluminescence (PL). We have found that the piezoelectric fields in (111)B samples affect the transient behavior of PL spectra. Compared with the reference (100) samples, we have confirmed that the piezoelectric effect induces slower exciton relaxation in (111)B strained quantum wells. (C) 1999 Elsevier Science Ltd. All rights reserved.
A novel technology to form air gap for ULSI application
(1999-04-01)
Chang, KM
;
Yang, JY
;
Chen, LW
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
In this letter, we develop a novel process to fill the interline space with air (dielectric constant = 1). A silicon wafer, whose face is downward, patterned with metal lines, is placed on the top of another silicon wafer coated with dry polyimide. Hydrogen silsesquioxanes (HSQ), FOx-16, is diluted and trickled through the slit between the metal lines and the polyimide. Then the HSQ forms an ultrathin liquid layer on the dry polyimide and contacts with the top of the metal lines. After the liquid HSQ becomes dry, the air gap is formed, The dry polyimide has good adhesion to silicon substrate but not to the dry FOx-16, so we can separate the polyimide from the dry FOx-16 and get the air gap. The liquid property of HSQ and its high selective adsorption between the metal lines and the polyimide are utilized to form the air gap.
Effective improvement on barrier capability of chemical vapor deposited WSix using N-2 plasma treatment
(1999-04-01)
Wang, MT
;
Lin, YC
;
Wang, CC
;
Chen, MC
;
電子工程學系及電子研究所
This work studies the thermal stability of Cu/WSx/p(+)-n and Cu/WSiN/WSix/p(+)-n diodes in which the WSix barrier layers were deposited by chemical vapor deposition to a thickness of about 50 nm using SiH4/WF6 chemistry with the SiH4/WF6 flow rates of 6/2 seem, while the WSiN layers were formed by in situ N-2 plasma treatment on the chemically vapor deposited WSix (CVD-WSix) surfaces. Without N-2 plasma treatment, the thermal stability of Cu/WSix (50 nm)/p(+)-n junction diodes was found to reach 500 degrees C; with N-2 plasma treatment, the resultant Cu/WSiN/WSix (50 nm)/p(+)-n junction diodes were able to retain integrity of electrical characteristics up to at least 600 degrees C. Failure mechanism of the WSiN/WSix bilayer in the Cu/WSiN/WSix/Si structure was closely related to the WSix/Si interface reaction and the tungsten silicide formation of the WSix layer. Thus, barrier capability of the WSiN/WSix bilayer can be further improved by suppressing the WSix/Si interface reaction and the silicidation of the WSix layer. The thermal stability of Cu/barrier/p(+)-n diodes was further raised to 650 degrees C by using a multilayer barrier structure of WSiN/Si-x (50 nm)/WSiN/WSix (10 nm) or a WSiN/WSiy (y > 1) barrier We conclude that the post-CVD-WSix treatment with in situ N-2 plasma is a simple, practical, and efficient method of improving the WSix-based barrier capability for Cu metallization. (C) 1999 The Electrochemical Society. S0013-4651(97)09-073-9. All rights reserved.
Optimum multicast of multimedia streams
(1999-04-01)
Wang, CF
;
Lai, BR
;
Jan, RH
;
資訊工程學系
;
Department of Computer Science
In a VOD system, multicast is a preferred method for saving network bandwidth. That is, customers requesting the same video program over a small time interval can be arranged in a multicast tree (group), and then the video server sends a video stream via this tree to customers. In this research, we considered how to arrange a set of multicast trees such that the number of customers served is maximized and the link capacity constraint is maintained. For a directed acyclic graph (DAG), we proposed a branch-and-bound algorithm to solve this problem and the solution method is illustrated by example. Next, we extended the algorithm to find an approximate solution for a general graph case. It is shown, through simulations on randomly generated graphs that the solution for our approximation method is very close to the optimal solution. (C) 1999 Elsevier Science Ltd. All rights reserved.
Common-path heterodyne interferometric detection scheme for measuring wavelength shift
(1999-04-01)
Lee, JY
;
Su, DC
;
光電工程學系
;
Department of Photonics
When a linearly polarized light passes through a uniaxial crystal, small wavelength shifts will introduce phase difference variations between s- and p-polarizations, These phase difference variations can be measured accurately by heterodyne interferometry. Based on these facts, a common-path heterodyne interferometric detection scheme for measuring wavelength shift is proposed. This scheme has the advantages of both common-path interferometry and heterodyne interferometry. (C) 1999 Elsevier Science B.V. All rights reserved.
Leakage current reduction of chemical-vapor-deposited Ta2O5 films on rugged polycrystalline silicon electrode for dynamic random access memory application
(1999-04-01)
Lin, M
;
Chang, CY
;
Huang, TY
;
Shieh, WY
;
電子工程學系及電子研究所
In this paper we describe the electrical and physical characterizations of Ta2O5 films on rapid thermal nitrided (RTN) rugged polycrystalline silicon electrodes for 256 M dynamic random access memory (DRAM) application. To overcome the higher leakage on Ta2O5 films with rugged poly-Si bottom electrodes, we have successfully employed a light oxidation on rugged poly-Si grains for improving the acute angle of surface morphology, and a post-treatment with rapid thermal nitridation of N2O on Ta2O5 films to reduce the leakage. In addition, a RTN pre-treatment is also applied to prevent rugged poly-Si oxidation during a Ta2O5 film deposition that compromises the effective Ta2O5 thickness. Our results show that Ta2O5 film with an effective thickness of 1.4 nm (physical thickness=10 nm) and a low leakage current density of less than 1 X 10(-8) A/cm(2), suitable for 256 M DRAM application, can be achieved. Our results also show that while a light oxidation on rugged poly-Si grains could improve the acute angle between the rugged poly-Si and its congruent amorphous silicon sub-layer, over oxidation on rugged poly-Si grains could degrade the leakage current and the time dependent dielectric breakdown (TDDB) characteristics of the stacked capacitor.
Collision efficiencies of algae and kaolin in depth filter: The effect of surface properties of particles
(1999-04-01)
Huang, CP
;
Pan, JRS
;
Huang, SH
;
環境工程研究所
;
Institute of Environmental Engineering
Column filtration experiments with 2 mm-Phi glass beads were conducted to investigate the behavior of colloids during filtration. Algae and kaolin were used as model particles, while the chemical system was altered by changing the electrolyte concentration and pH. The collision efficiencies from the interaction between colloids and the filter medium were calculated with a semi-empirical approach of the single sphere model and clean-bed filtration theory. The experimental results indicate that ionic strength enhance the removal efficiencies for both algae and kaolin particles significantly. The removal efficiency of the filter for algae decreased with the increase in pH for up to pH 6. No significant change was observed beyond pH 6. Removal efficiencies for kaolin decreased with an increase in pH. It is concluded that collision efficiencies are sensitive to ion strength and pH. (C) 1999 Elsevier Science Ltd. All rights reserved.
A novel transient simulation for 3-D multilevel interconnections on complex topography
(1999-04-01)
Hou, HM
;
Sheen, CS
;
Wu, CY
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
An efficient method is presented to model the transient characteristics of distributed resistor-capacitor of ULSI multilevel interconnections on complex topography, in which the reformulation of the boundary-element method (BEM) and the Pade-via-Lanczos (PVL) algorithm associated with multilayer Green's function can avoid the redundant works on both volume mesh and transient analysis associated with the finite-difference method. An adaptive multilayer Green's function is adopted to investigate several cases that have revealed interesting physical mechanisms in charge transfer between conductors on multilayer topography. To improve the timing analysis efficiency of the finite-difference method, the dominant poles are obtained by introducing the PVL algorithm for model-ol der reduction. Hence, it is easy to calculate the transient characteristics of both parallel conductors and complicated configurations such as crossing lines, corners, contacts, multilayers, and their combinations.
Improvement of ultra-thin 3.3 nm thick oxide for co-salicide process using NF3 annealed poly-gate
(1999-04-01)
Chang, TY
;
Lei, TF
;
Chao, TS
;
Huang, CT
;
Chen, SK
To get high quality ultra-thin oxide is very important and difficult for IC industry now. Using NF3 annealed poly-Si gate to improve gate oxide integrity is described. However, reducing fate, source and drain parasitic resistance with gate lengths down to 0.2 mu m is another key point. Co-salicide process can successfully reduce the gate resistance even for a gate length of 0.075 mu m. Although, Co-salicide process has a leakage problem. Using NF3 annealing to prevent Co diffusing into gate oxide is described too. Results show that the optimal NF3 annealing significantly improves electrical characteristics of ultra-thin oxide and Co-salicide process in terms of leakage current and breakdown field, as compared to the samples without NF3 annealing.
Fuzzy neural network approach for 2-D direction finding in multipath environments
(1999-04-01)
Ma, CW
;
Teng, CC
;
電控工程研究所
;
Institute of Electrical and Control Engineering
A fuzzy neural network (FNN) approach for estimating the two-dimensional (2-D) direction of a radiating source in coherent multipath environments via a 2-D passive sensor array is presented. Outputs of the array are preprocessed by a judiciously constructed reference-point preprocessing scheme to produce proper inputs for an FNN. The FNN then uses these preprocessed outputs to produce the estimate of the source direction. Since the preprocessed outputs preserve enough information about the source direction and the FNN maps the preprocessed outputs into the source direction with high accuracy, the FNN approach exhibits good estimation performance. By computer simulations, it is found that the FNN approach drastically outperforms the spatial smoothing 2-D MUSIC algorithm.