Browsing by Issue Date, starting with "1997-12-15"

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私房名菜
(1997-12-15)
管管
Growth and X-ray characterization of an InN film on sapphire prepared by metalorganic vapor phase epitaxy
(1997-12-15)
Chen, WK
;
Pan, YC
;
Lin, HC
;
Ou, J
;
Chen, WH
We report the successful growth of an InN film by metalorganic vapor phase epitaxy. The film quality is found to be strongly dependent on the growth temperature and the TMIn reactant flow rate. The best quality epilayer was obtained at 375 degrees C under a high V/III ratio growth environment. It exhibits a FWHM of the X-ray rocking curve as narrow as 96 arcsec: which explains the superior crystalline quality of our epitaxial film.
Growth and X-ray characterization of an InN film on sapphire prepared by metalorganic vapor phase epitaxy
(1997-12-15)
Chen, WK
;
Pan, YC
;
Lin, HC
;
Ou, J
;
Chen, WH
We report the successful growth of an InN film by metalorganic vapor phase epitaxy. The film quality is found to be strongly dependent on the growth temperature and the TMIn reactant flow rate. The best quality epilayer was obtained at 375 degrees C under a high V/III ratio growth environment. It exhibits a FWHM of the X-ray rocking curve as narrow as 96 arcsec: which explains the superior crystalline quality of our epitaxial film.
Photoemission and photoabsorption study of C-60 adsorption on Cu(111) surfaces
(1997-12-15)
Tsuei, KD
;
Yuh, JY
;
Tzeng, CT
;
Chu, RY
;
Chung, SC
We have carried out an extensive study of C-60 adsorption on Cu(111) surfaces using low-energy electron diffraction, photoemission, and x-ray-absorption spectroscopy. It is found that in valence-band photoemission a state forms right below the Fermi energy for an annealed, well-ordered monolayer, similar to the case of K-doped C-60. This peak disperses across the Fermi energy at off normal emission geometry. The spectra of carbon core-level photoemission show that the line shape is highly asymmetric with a metalliclike tail. The carbon near-edge absorption spectra show that the lowest unoccupied molecular orbital (LUMO) is attenuated, and a clear Fermi edge jump appears at the absorption onset. This evidence indicates that charge transfers from the substrate to the C-60 molecular orbitals and the overlayer becomes metallic. The amount of charge transfer can be determined to be 1.5-2 electrons per molecule from both the area of the occupied LUMO in photoemission and the peak shift in near-edge absorption spectra. It has been reported that many metal surfaces with originally different work functions covered by a monolayer of C-60 have a similar work function of about 5 eV. We suggest that the measured work functions are due to the metallic C-60 overlayers and are similar regardless of the metal substrates. This is in line with the reported alignment of monolayer energy levels to substrate Fermi energy. Since the work functions are similar, the energy levels with respect to the vacuum level are also similar. Finally we compare near-edge x-ray-absorption with inverse photoemission spectroscopy to address the screening effects.
A new method for tool steel materials selection under fuzzy environment
(1997-12-16)
Chen, SM
;
交大名義發表
;
資訊工程學系
;
National Chiao Tung University
;
Department of Computer Science
This paper presents a new method to solve the tool steel materials selection problem under fuzzy environment, where the importance weights of different criteria and the ratings of various alternatives under different criteria are assessed in linguistic terms represented by fuzzy numbers. Because proposed method uses simple arithmetic operations rather than the complicated arithmetic operations for aggregation and ranking of fuzzy numbers described in Wang and Chang (1995), its execution is much faster than the one presented in Wang and Chang (1995). (C) 1997 Elsevier Science B.V.
A new method for tool steel materials selection under fuzzy environment
(1997-12-16)
Chen, SM
;
資訊工程學系
;
Department of Computer Science
This paper presents a new method to solve the tool steel materials selection problem under fuzzy environment, where the importance weights of different criteria and the ratings of various alternatives under different criteria are assessed in linguistic terms represented by fuzzy numbers. Because proposed method uses simple arithmetic operations rather than the complicated arithmetic operations for aggregation and ranking of fuzzy numbers described in Wang and Chang (1995), its execution is much faster than the one presented in Wang and Chang (1995). (C) 1997 Elsevier Science B.V.
Least-squares finite element methods for the elasticity problem
(1997-12-18)
Yang, SY
;
Liu, JL
;
應用數學系
;
Department of Applied Mathematics
A new first-order system formulation for the linear elasticity problem in displacement-stress form is proposed. The formulation is derived by introducing additional variables of derivatives of the displacements, whose combinations represent the usual stresses. Standard and weighted least-squares finite element methods are then applied to this extended system. These methods offer certain advantages such as that they need not satisfy the inf-sup condition which is required in the mixed finite element formulation, that a single continuous piecewise polynomial space can be used for the approximation of all the unknowns, that the resulting algebraic systems are symmetric and positive definite, and that accurate approximations of the displacements and the stresses can be obtained simultaneously. With displacement boundary conditions, it is shown that both methods achieve optimal rates of convergence in the H-1-norm and in the L-2-norm for all the unknowns. Numerical experiments with various Poisson ratios are given to demonstrate the theoretical error estimates.
Characterization of GaN epitaxial layers on SiC substrates with AlxGa1-xN buffer layers
(1997-12-18)
Lin, CF
;
Cheng, HC
;
Feng, MS
;
Chi, GC
;
材料科學與工程學系
High quality GaN epitaxial layers were obtained with AlxGa1-xN buffer layers on 6H-SiC substrates. The low-pressure metalorganic chemical vapor deposition (LP-MOCVD) method was used. The 500 Angstrom thick buffer layers of AlxGa1-xN (0 less than or equal to x less than or equal to 1) were deposited on SiC substrates at 1025 degrees C. The FWHM of GaN (0004) X-ray curves are 2-3 arcmin, which vary with the Al content in AlxGa1-xN buffer layers. An optimum Al content is found to be 0.18. The best GaN epitaxial film has the mobility and carrier concentration about 564 cm(2) V-1 s(-1) and 1.6 x 10(17) cm(-3) at 300 K. The splitting diffraction angle between GaN and AlxGa1-xN were also analyzed from X-ray diffraction curves. (C) 1997 Elsevier Science S.A.
Least-squares finite element methods for the elasticity problem
(1997-12-18)
Yang, SY
;
Liu, JL
;
應用數學系
;
Department of Applied Mathematics
A new first-order system formulation for the linear elasticity problem in displacement-stress form is proposed. The formulation is derived by introducing additional variables of derivatives of the displacements, whose combinations represent the usual stresses. Standard and weighted least-squares finite element methods are then applied to this extended system. These methods offer certain advantages such as that they need not satisfy the inf-sup condition which is required in the mixed finite element formulation, that a single continuous piecewise polynomial space can be used for the approximation of all the unknowns, that the resulting algebraic systems are symmetric and positive definite, and that accurate approximations of the displacements and the stresses can be obtained simultaneously. With displacement boundary conditions, it is shown that both methods achieve optimal rates of convergence in the H-1-norm and in the L-2-norm for all the unknowns. Numerical experiments with various Poisson ratios are given to demonstrate the theoretical error estimates.
Relation between fluxes for membrane reaction-diffusion transport studied by the matrix method
(1997-12-22)
Chen, JS
;
Chang, WY
;
應用化學系
;
Department of Applied Chemistry
The previous matrix-theoretical analysis of the time lags and mean first passage times for reaction-diffusion transport in the Laplace domain [J. Chem. Phys. 106, 8022 (1997)] has been extended to the problems of membrane permeation, absorption and desorption. A matrix transport equation has been derived to calculate the flux (in the Laplace domain) for specified initial and boundary conditions corresponding to membrane permeation, absorption or desorption. Seven equality relations between fluxes for reaction-free diffusion and one for diffusion accompanying reaction have been found. Among them are two new equality relations which have been discovered by this matrix analysis. (C) 1997 American Institute of Physics.
Relation between fluxes for membrane reaction-diffusion transport studied by the matrix method
(1997-12-22)
Chen, JS
;
Chang, WY
;
應用化學系
;
Department of Applied Chemistry
The previous matrix-theoretical analysis of the time lags and mean first passage times for reaction-diffusion transport in the Laplace domain [J. Chem. Phys. 106, 8022 (1997)] has been extended to the problems of membrane permeation, absorption and desorption. A matrix transport equation has been derived to calculate the flux (in the Laplace domain) for specified initial and boundary conditions corresponding to membrane permeation, absorption or desorption. Seven equality relations between fluxes for reaction-free diffusion and one for diffusion accompanying reaction have been found. Among them are two new equality relations which have been discovered by this matrix analysis. (C) 1997 American Institute of Physics.
The influence of magnesium on carbide characteristics and creep behavior of the Mar-M247 superalloy
(1997-12-22)
Bor, HY
;
Chao, CG
;
Ma, CY
;
材料科學與工程學系
;
Department of Materials Science and Engineering
The study on microstructural and mechanical properties of weld heat affected zone of 7075-T651 aluminum alloy
(1997-12-22)
Hwang, RY
;
Chou, CP
;
機械工程學系
;
Department of Mechanical Engineering
Temperature dependence of Fermi level obtained by electroreflectance spectroscopy of undoped n(+)-type doped GaAs
(1997-12-29)
Huang, KM
;
Wang, KL
;
Wang, DP
;
Huang, KF
;
Huang, TC
The electroreflectance (ER) spectra of an undoped n(+)-type doped GaAs have been measured over a range of temperature from 25 to 400 K. Many Franz-Keldysh oscillations were observed above the band-gap energy, which enabled the electric field strength and, hence, also the Fermi level to be determined. The photovoltaic effect is shown to be negligible, even at the low temperature. The experiment shows that the Fermi level decreases with increasing temperature and has almost the same temperature dependence as the energy gap. It is pinned at about 0.63 of energy gap below the conduction band. (C) 1997 American Institute of Physics.
Synthesis of 4-oxo- and 4-anti-formyl-8,10,12,13-tetraoxapentacyclo[5.5.1.0(2,6).0(3,11).0(5,9)]tridecanes
(1997-12-29)
Wu, HJ
;
Chern, JH
;
應用化學系
;
Department of Applied Chemistry
The synthesis of 4-oxo- and 4-anti-formyl-8,10,12,13-tetraoxapentacyclo[5.5.1.0(2,6).0(3,11).0(5,9)]tridecanes has been accomplished. Ozonolysis of compounds 10a,b and 12a-c in dichloromethane at -78 degrees C followed by reduction with dimethyl sulfide gave the title compounds, 4-oxo-tetraoxa-cages 11a,b and 14a-c, in moderate yields. Ozonolysis of the endo-syn isomers 15a,b and 18a,b under the same reaction conditions gave 4-anti-formyl-tetraoxa-cages 17a,b and 20a,b, respectively. (C) 1997 Published by Elsevier Science Ltd.
Synthesis of 4-oxo- and 4-anti-formyl-8,10,12,13-tetraoxapentacyclo[5.5.1.0(2,6).0(3,11).0(5,9)]tridecanes
(1997-12-29)
Wu, HJ
;
Chern, JH
;
交大名義發表
;
應用化學系
;
National Chiao Tung University
The synthesis of 4-oxo- and 4-anti-formyl-8,10,12,13-tetraoxapentacyclo[5.5.1.0(2,6).0(3,11).0(5,9)]tridecanes has been accomplished. Ozonolysis of compounds 10a,b and 12a-c in dichloromethane at -78 degrees C followed by reduction with dimethyl sulfide gave the title compounds, 4-oxo-tetraoxa-cages 11a,b and 14a-c, in moderate yields. Ozonolysis of the endo-syn isomers 15a,b and 18a,b under the same reaction conditions gave 4-anti-formyl-tetraoxa-cages 17a,b and 20a,b, respectively. (C) 1997 Published by Elsevier Science Ltd.
管管這一年十分熱鬧
(1997-12-31)
亮
Chimney-shaped and plateau-shaped gate electrode field emission arrays
(1998)
Tarntair, FG
;
Wang, CC
;
Hong, WK
;
Huang, HK
;
Cheng, HC
A triode structure of chimney-shaped field emitter arrays is proposed in this article. This triode structure includes the chimney-shaped emitter, thermal oxidation dioxide, and the plateau-shaped singlecrystalline silicon gate electrode. For the application of the matrix-addressable and large area flat panel display, the uniform structure of the emitters and the yield become critical manufacturing issues when attempting to control nano-meter size features. The uniformity and yield of the chimney-shaped emitters are very well controlled. The nano-sized gate-to-emitter separations can be created by the changing thickness of the insulator. The uniformity of the insulator and emitter material can be controlled within 3% which can be obtained by most large area thin film deposition tools, not by photolithography.
負型的古典距離正則圖之研究
(1998)
翁志文
;
WENG CHIH-WEN
;
交通大學應用數學系
The reliability of amorphous silicon thin film transistors for LCD under DC and AC stresses
(1998)
Cheng, HC
;
Huang, CY
;
Lin, JW
;
Kung, JJH
;
電子工程學系及電子研究所
In this paper, hydrogenated amorphous silicon and polycrystalline silicon thin film transistors have been stressed with various conditions including DC and AC. The charge trapping and defect state creation are the two mechanisms to degrade the transfer characteristics of the TFTs. For a-Si.H TFTs, the charge trapping occurs at high silicon content of silicon nitride (SiNx) gate dielectrics or performs at high gate electrical field. Defect stale creation dominates at low hydrogen concentration in a-Si:H. At the performance of AC signal, the degradation of transfer curves is associated with bias, frequency, and duty cycle. The characteristics of a-Si:PI TFTs shift more with increasing bias voltage and duty cycle. For the frequency effect, the transfer characteristics of a-Si:H TFTs decrease with increasing AC frequency under negative AC signal stress, however, they are independent of the frequency under positive AC signal stress.