Browsing by Issue Date, starting with "1996-07-29"

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Picosecond photoresponse of carriers in Si ion-implanted Si
(1996-07-29)
Chin, A
;
Lee, KY
;
Lin, BC
;
Horng, S
;
電子工程學系及電子研究所
Picosecond photoresponse of carriers in Si ion-implanted Si samples has been measured using femtosecond transient reflectivity measurement. A threshold peak implant dose of 10(16) cm(-2) is required to achieve picosecond carrier lifetime. At this dosage, carrier lifetimes of 0.9 and 1.4 ps are measured for the as-implanted and 400 degrees C annealed Si substrates, respectively. The increase in carrier lifetime upon annealing is attributed to the reduction in the concentration of trap and recombination centers. Sheet resistance also shows a strong dependence on the annealing temperature. An eightfold increase in sheet resistance is obtained for annealed samples, and a reduction in hopping conduction, manifested by the e(-1/T) temperature dependence, may be responsible for the increase in resistance. Further evidence of decreasing hopping conduction can be also observed from the more than two orders of magnitude in reduction of sheet resistance as the peak dosage decreases from 10(16) to 10(14) cm(-2). (C) 1996 American Institute of Physics.
管管作品三首
(1996-07-31)
管管
管管作品三首
(1996-07-31)
管管
管管作品三首
(1996-07-31)
管管
Analysis on machined feature recognition techniques based on B-rep
(1996-08-01)
Wu, MC
;
Liu, CR
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
Solving the machine feature recognition problem has been widely recognized as a cornerstone for developing an automated process planning system directly linked to a CAD system. Various recognition techniques have been developed; however, they are in general deficient in robustness. That is, valid machined features may not be recognized and features which are recognized may not be valid in practice. This paper is intended to analyse the existing machined feature recognition techniques, which are based on the B-rep solid modelling scheme, in order to give the reasons why the robustness problem would occur. The pros and cons for recognizing machined features are also analysed. Finally, a cutter selection methodology, known as process requirement modelling, is introduced; this methodology seems to provide a promising way to solve the machined feature recognition problem. Copyright (C) 1996 Elsevier Science Ltd.
Stress in liquid-phase deposited oxide films
(1996-08-01)
Yeh, CF
;
Lin, SS
;
Lur, WT
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
To To develop a low-stress dielectric thin film, a novel liquid-phase deposition (LPD) technique utilizing silica-saturated hydrofluosilicic (H2SiF6) solution with only H2O added is proposed. Due to fluorine incorporation, the stress in as deposited LPD oxide can be as low as 83.3 MPa (tensile). Addition of H2O greatly affects the stresses in as-deposited LPD oxide: the less H2O added, the lower the stress will be. The stress variations accompanying thermal cycling have also been larger quantity of H2O added exhibited larger stress variations (hysteresis). After ex situ annealing at around 600 degrees C, the total stress decreased to near 0 MPa.
Automatic control for chemical dosing in laboratory-scale coagulation process by using an optical monitor
(1996-08-01)
Huang, CP
;
Liu, CB
;
交大名義發表
;
環境工程研究所
;
National Chiao Tung University
The feasibility of applying an optical monitor in the automatic control of coagulation was assessed in this study. Prior to simulation testing, a series of batch tests was performed to determine the optimum state of dosing corresponding to the monitor's output. The results indicate that floc density decreased as floc size increased under the same coagulant dosage. Moreover, ratio output of the monitor could provide an index for evaluating the change trend of flee size in flocculation and for predicting the potential of flee settling. An automatic control system was designed and connected to a laboratory-scale water treatment process. A computer in the automatic control system received all the ratio values with respect to the progressive dosing. After determining the dosage, the system terminated the function of control. This control system started performing a new test for determining another optimum dosage when the fluctuation of inflow turbidity was more than a designated value. Simulation tests demonstrated that the PDA monitor with a designed control system could be successfully applied in the on-line control of coagulation dosing. The recommended control parameters for the control system was also identified. Copyright (C) 1996 Elsevier Science Ltd
A new intensity stereo coding scheme for MPEG1 audio encoder - Layers I and II
(1996-08-01)
Liu, CM
;
Liu, JC
;
交大名義發表
;
資訊工程學系
;
National Chiao Tung University
In MPEG I audio compression standard, the intensity stereo coding scheme is a keg, technology to achieve a bit rate lower than 2x128 kbit/s for stereophonic signals while preserving high audio quality. However, the intensity coding scheme has difficulties in signal cancellation and scalefactor consistency. This paper shows that the Karhunen-Loeve (KL) transform can be applied to the intensity coding for solving the two problems. In this paper, we present true methods to implement the Karhunen-Loeve transform in the MPEG 1 layers I and II. Among the two methods, one is fully compatible with the MPEG1 while the other need a slight coding of modification on the MPEG coding process. All the conclusion. two methods are tested to have better audio quality than the technique indicated by the MPEG 1 layers 1 and II.
Enhanced metalorganic chemical vapor deposition titanium nitride film fabricated using tetrakis-dimethylamino-titanium for barrier metal application in sub-half-micron technology
(1996-08-01)
Wang, CK
;
Liu, LM
;
Liao, M
;
Cheng, HC
;
Lin, MS
Enhanced metalorganic chemical vapor deposition (MOCVD) titanium nitride (TiN:C) film with low resistivity (< 700 mu Omega . cm) has been fabricated by thermal decomposition of tetrakis-dimethylamino-titanium (TDMAT; Ti[N(CH3)(2)](4)) Enhancement is carried out by in-situ N-2 plasma treatment of as-deposited TiN:C film and the enhanced TiN:C film has good stability: less than 4% increase in film resistivity after exposure to air for 24 days. The amount of oxygen absorbed in this enhanced TiN:C film after air exposure, determined by Auger electron spectroscopy (AES) was significantly reduced. This enhanced MOCVD TiN:C film has been successfully applied to sub-half-micron devices. A void-tree tungsten plug (W plug) for sub-half-micron holes can be achieved. Good barrier performance and low contact/via resistance have also been demonstrated.
A method for rectifying grid junctions in grid-coded images using cross ratio
(1996-08-01)
Chia, TL
;
Chen, Z
;
Yueh, CJ
;
資訊科學與工程研究所
;
Institute of Computer Science and Engineering
In the grid-coding technique, the accurate grid junction locations are vital to the surface computation. Noise arising from the imaging formation and processing processes will jeopardize the computation accuracy. The objective of this study is to make use of the geometric property of cross ratio to improve the accuracy of grid junction locations in grid-coded images., A method is devised to regenerate grid junctions from the original (i.e., raw) junction data of an image. Through a statistical error analysis, we show that the regenerated junction data are generally more accurate than the old ones in the image taken from a wide range of viewing angles.
Styrene/maleimide copolymer with stable second-order optical nonlinearity
(1996-08-01)
Sung, PH
;
Chen, CY
;
Wu, SY
;
Huang, JY
;
光電工程學系
Radical copolymerization of N-(azo dye) maleimide or N-(substituted phenyl) maleimide and styrene were carried out using 2,2'-azobis-isobutyronitrile as an initiator in THF at 60 degrees C. These copolymers exhibit high solubility in most of the organic solvents and excellent thermal stability up to 280 degrees C under nitrogen atmosphere. The copolymer films which were heated at 200-240 degrees C under high corona field exhibit d(33) = 3-5 pm/V, in the Maker-fringe measurement. Experimental results also showed that the copolymer with azo dye as chromophore did not decay in second harmonic response even at 130 degrees C. (C) 1996 John Wiley & Sons, Inc.
Analytical spatio-temporal design of Kerr lens mode-locked laser resonators
(1996-08-01)
Lin, KH
;
Hsieh, WF
;
光電工程研究所
;
Institute of EO Enginerring
An analytical method of spatio-temporal design for a Kerr lens mode-locked Ti:sapphire laser is presented. Various spatial and temporal effects are considered to derive simple quadratic equations of the pulse width for both standing- and traveling-wave cavities. By solving the quadratic equation, we obtain the relations between pulse width and other cavity parameters for a given system for optimal design of a Kerr lens mode-locked cavity and to generate the shortest laser pulses. Our theoretical results agree well with the experimental results, and the computation time of this analytic approach for cavity parameters is reduced drastically as compared with an iteratively numerical approach. (C) 1996 Optical Society of America.
Contradirectional two-wave mixing with partially coherent waves in photorefractive crystals
(1996-08-01)
Yi, XM
;
Lin, SH
;
Yeh, PC
;
Hsu, KY
;
光電工程學系
We investigate contradirectional two-wave mixing with partially coherent waves in photorefractive crystals in the nondepleted pump regime. Equations governing the propagation of the self-coherence function and the mutual-coherence function of the signal wave and the pump wave are derived and simulated numerically. Numerical solutions of these equations are in excellent agreement with the experimental measurements. (C) 1996 Optical Society of America
Schottky contact and the thermal stability of Ni on n-type GaN
(1996-08-01)
Guo, JD
;
Pan, FM
;
Feng, MS
;
Guo, RJ
;
Chou, PF
The Schottky barrier height of Ni on n-GaN has been measured to be 0.56 and 0.66 eV by capacitance-voltage (C-V) and current-density-temperature (J-T) methods, respectively. Gallium nickel (Ga4Ni3) is formed as Ni is deposited on the GaN film, which affects the barrier height markedly. The thermal stability of Ni on GaN is also investigated by annealing these specimens at various temperatures. Specimen annealing at temperatures above 200 degrees C leads to the formation of nickel nitrides Ni3N and Ni4N at the interface of Ni and GaN. These interfacial compounds change the measured barrier height to 1.0 and 0.8 eV by C-V and J-T methods, respectively. Comparisons of Schottky characteristics of Ni with those of Pt, Pd, Au, and Ti are also discussed. (C) 1996 American Institute of Physics.
Atomic force microscopy study on the surface structure of oxidized porous silicon
(1996-08-01)
Young, TF
;
Huang, IW
;
Yang, YL
;
Kuo, WC
;
Jiang, IM
We study the surface structure of porous silicon (PS) using atomic force microscopy (AFM), before and after oxidation in a HNO3 solution. The AFM image shows the PS surface with a self-affine random fractal structure of wires, hillocks and voids in various scales. After oxidization the wires and hillocks of PS structures are glazed with oxide and the voids are filled, PS structure is altered to a simple self-affine fractal structure of hillock clusters. The fractal dimension D of PS is around 2.3, which decreases with increasing oxidization to about 2.0 of a smooth surface for the saturated oxidization. Our direct observation of the fractal structure of PS from AFM data reveals a good explanation for the recently found novel nonlinear de-response in Ag thin films deposited on PS. We find the fractal surface structure of oxidized PS responds to the stepwise avalanche electric breakdown of the resistivity of Ag thin films deposited on oxidized PS.
Efficient fibre-coupled laser diode end-pumped NYAB laser
(1996-08-01)
Chen, YF
;
Wang, SC
;
Kao, CF
;
Huang, TM
;
光電工程學系
Under optimum pump conditions, 60mW of green laser output corresponding to a conversion efficiency 6% was obtained from a self-frequency-doubling NYAB crystal when pumped by a 1W fibre-coupled laser diode. The prospect of higher conversion efficiency is also discussed.
On minimal cost-reliability ratio spanning trees and related problems
(1996-08-01)
Chang, YC
;
Hsu, LH
;
資訊工程學系
;
Department of Computer Science
The minimal cost-reliability ratio spanning tree problem is to find a spanning tree such that the cost-reliability ratio is minimized. This problem can also be treated as a specific version of a more generalized problem discussed by Hassin and Tamir. By Hassin and Tamir's approach, the minimal cost-reliability ratio spanning tree problem can be solved in O(q(4)) where q is the number of edges in the graph. In this paper, we reduce the complexity of the algorithm proposed by Hassin and Tamir to O(q(3)). Furthermore using our approach, related algorithms proposed by Hassin and Tamir can also be improved by a factor of O(q).
Horizontal flow boiling of R22 and R407C in a 9.52mm micro-fin tube
(1996-08-01)
Kuo, CS
;
Wang, CC
;
機械工程學系
;
Department of Mechanical Engineering
The two-phase heat transfer coefficient and pressure drop characteristics of refrigerant R22 and R407C (a mixture of R32/R125/R134a, 23%/25%/52%) in a micro-fin tube with nominal diameter 9.52 mm were presented in this study. Experimental data were taken at an evaporation pressure of 600 kPa. The mass flux was between 100 and 300 kg/m(2) . s and the heat fluxes were between 6 and 14 kW/m(2). Experimental data were presented in the form of length-averaged heat transfer coefficients and frictional pressure gradients. The effect of heat flux and mass flux on the heat transfer coefficients were also reported in the present investigation. It is found that the heat transfer coefficients for R407C are considerably lower than R22 (50 similar to 80% less), and the pressure drop of R407C is 30 similar to 50% lower as compared to R22. Copyright (C) 1996 Elsevier Science Ltd
Automatic control for chemical dosing in laboratory-scale coagulation process by using an optical monitor
(1996-08-01)
Huang, CP
;
Liu, CB
;
環境工程研究所
;
Institute of Environmental Engineering
The feasibility of applying an optical monitor in the automatic control of coagulation was assessed in this study. Prior to simulation testing, a series of batch tests was performed to determine the optimum state of dosing corresponding to the monitor's output. The results indicate that floc density decreased as floc size increased under the same coagulant dosage. Moreover, ratio output of the monitor could provide an index for evaluating the change trend of flee size in flocculation and for predicting the potential of flee settling. An automatic control system was designed and connected to a laboratory-scale water treatment process. A computer in the automatic control system received all the ratio values with respect to the progressive dosing. After determining the dosage, the system terminated the function of control. This control system started performing a new test for determining another optimum dosage when the fluctuation of inflow turbidity was more than a designated value. Simulation tests demonstrated that the PDA monitor with a designed control system could be successfully applied in the on-line control of coagulation dosing. The recommended control parameters for the control system was also identified. Copyright (C) 1996 Elsevier Science Ltd
Movement-based location update and selective paging for PCS networks
(1996-08-01)
Akyildiz, IF
;
Ho, JSM
;
Lin, YB
;
資訊工程學系
;
Department of Computer Science
This paper introduces a mobility tracking mechanism that combines a movement-based location update policy with a selective paging scheme, Movement-based location update is selected for its simplicity. It does not require each mobile terminal to store information about the arrangement and the distance relationship of all cells, In fact, each mobile terminal only keeps a counter of the number of cells visited, A location update is performed when this counter exceeds a predefined threshold value, This scheme allo cvs the dynamic selection of the movement threshold on a per-user basis, This is desirable as different users may have very different mobility patterns, Selective paging reduces the cost for locating a mobile terminal in the expense of an increase in the paging delay, In this paper, we propose a selective paging scheme which significantly decreases the location tracking cost under a small increase in the allowable paging delay, We introduce an analytical model for the proposed location tracking mechanism which captures the mobility and the incoming call arrival patterns of each mobile terminal, Analytical results are provided to demonstrate the cost-effectiveness of the proposed scheme under various parameters.