Browsing by Author "Wang, JP"

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Interdiffusion of multilayer ferroelectric thin films using YBa2Cu3O7-x as an intermediate layer
(1996-05-15)
Wang, JP
;
Ling, YC
;
Lin, IN
;
Lin, WJ
;
Tseng, TY
Interdiffusion between layers in multilayer ferroelectric thin films was studied from their elemental depth profiles using secondary ion mass spectrometry. Among the films deposited on YBa2Cu3O7-x/CeO2/Si substrates, the interdiffusion is most pronounced for [Sr0.5Ba0.5]Nb2O6(SBN) films, less marked for Pb0.97La0.03(Zr1-xTix)(0.9925)O-3 (PLZT, x=0.54 or 0.34) films, and is least significant for BaTiO3 films. Higher substrate temperature used for growing SBN films is believed to be the main cause of interdiffusion. The larger proportion of cationic vacancies existing in PLZT films is another possible source inducing interdiffusion. Using YBa2Cu3O7-x/SrTiO3 as substrates substantially reduces the interdiffusion between layers. This is ascribed to the better crystallinity of the YBa2Cu3O7-x layers deposited on SrTiO3 substrates. These results indicate that both the characteristics of ferroelectric films and the underlying YBa2Cu3O7-x layers substantially modify the interdiffusion behavior between the layers. (C) 1996 American Institute of Physics.
Off-axial pulse propagation in graded-index materials with Kerr nonlinearity - A variational approach
(1996-07-01)
Chien, CH
;
Yu, SS
;
Lai, YC
;
Wang, JP
;
光電工程學系
We analyze off-axial, self-focused pulse propagation in graded-index Kerr materials with the variational method. Equations which determine the characteristics of the beam, namely the optical path, the wavefront curvature, the beam width, and the pulse duration are derived and solved. We show that continuously adjustable negative group-velocity dispersion can be generated by off-axial propagation, and for pulse energy smaller than a critical value, negative group-velocity dispersion and Kerr nonlinearity warrant the existence of stable spatio-temporal solitary pulses.
Off-axial pulse propagation in graded-index materials with Kerr nonlinearity - A variational approach
(1996-07-01)
Chien, CH
;
Yu, SS
;
Lai, YC
;
Wang, JP
;
光電工程研究所
We analyze off-axial, self-focused pulse propagation in graded-index Kerr materials with the variational method. Equations which determine the characteristics of the beam, namely the optical path, the wavefront curvature, the beam width, and the pulse duration are derived and solved. We show that continuously adjustable negative group-velocity dispersion can be generated by off-axial propagation, and for pulse energy smaller than a critical value, negative group-velocity dispersion and Kerr nonlinearity warrant the existence of stable spatio-temporal solitary pulses.
The surface effect on Au 4f X-ray photoelectron spectra
(1996-02-01)
Wang, JP
;
Tung, CJ
;
Chen, YF
;
Kwei, CM
;
電子工程學系及電子研究所
An investigation of the surface effect on Au 4f X-ray photoelectron spectra was made for different emission angles, It was found that surface plasmon excitations made significant contributions to the spectra in single and plural energy-loss peaks and in the multiple loss background, Our approach involved Monte Carlo simulations of photoelectrons in the interior region of the solid and Poisson stochastic processes in the surface region. The partial-wave expansion method with the Hartree-Fock-Wigner-Seitz potential for the solid was used to calculate differential electron elastic scattering cross sections. An extended Drude dielectric function model was employed to compute electron differential inverse mean free paths for volume excitations. The inelastic mean free paths in the surface region became spatially-varying and were calculated. Differential probabilities for surface excitations were determined using the same model dielectric function. The computed X-ray photoelectron spectra including surface excitations agreed quite well with experimental data.