Browsing by Author "Li, Y"

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A comparison of quantum correction models for nanoscale MOS structures under inversion conditions
(2005)
Li, Y
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友訊交大聯合研發中心
;
D Link NCTU Joint Res Ctr
Quantum correction model features the correction of the inversion layer charge on different classical transport models in semiconductor device simulation. This approach has successfully been of great interest in the recent years. Considering a metal-oxide-semiconductor (MOS) structure in this paper, the Hansch, the modified local density approximation (MLDA), the density-gradient (DG), the effective potential (EP), and our models are investigated computationally and compared systematically with the result of the Schrodinger-Poisson (SP) model. In terms of the accuracy for (1) the position of the charge concentration peak, (2) the maximum of the charge concentration, (3) the total inversion charge sheet density, and (4) the average inversion charge depth, these well-established models are examined simultaneously. The DG model requires the solution of a boundary value problem, the EP model overestimates the position of the charge concentration peak and the maximum of the charge concentration, our explicit model demonstrates good accuracy among models.
A practical implementation of parallel dynamic load balancing for adaptive computing in VLSI device simulation
(2002)
Li, Y
;
Sze, SM
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Chao, TS
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電子工程學系及電子研究所
;
友訊交大聯合研發中心
We present a new parallel semiconductor device simulation using the dynamic load balancing approach. This semiconductor device simulation based on the adaptive finite volume method with a posteriori error estimation has been developed and successfully implemented on a 16-PC Linux cluster with a message passing interface library. A constructive monotone iterative technique is also applied for solution of the system of nonlinear algebraic equations. Two different parallel versions of the algorithm to perform a complete device simulation are proposed. The first is a dynamic parallel domain decomposition approach, and the second is a parallel current-voltage characteristic points simulation. This implementation shows that a well-designed load balancing simulation can significantly reduce the execution time up to an order of magnitude. Compared with the measured data, numerical results on various submicron VLSI devices are presented, to show the accuracy and efficiency of the method.
Electron energy state spin-splitting in 3D cylindrical semiconductor quantum dots
(2002-08-01)
Li, Y
;
Voskoboynikov
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Lee, CP
;
Sze, SM
;
Tretyak, O
In this article we study the impact of the spin-orbit interaction on the electron quantum confinement for narrow gap semiconductor quantum dots. The model formulation includes: (1) the effective one-band Hamiltonian approximation; (2) the position- and energy-dependent quasi-particle effective mass approximation; (3) the finite hard wall confinement potential; and (4) the spin-dependent Ben Daniel-Duke boundary conditions. The Hartree-Fock approximation is also utilized for evaluating the characteristics of a two-electron quantum dot system. In our calculation, we describe the spin-orbit interaction which comes from both the spin-dependent boundary conditions and the Rashba term (for two-electron quantum dot system). It can significantly modify the electron energy spectrum for InAs semiconductor quantum dots built in the GaAs matrix. The energy state spin-splitting is strongly dependent on the dot size and reaches an experimentally measurable magnitude for relatively small dots. In addition, we have found the Coulomb interaction and the spin-splitting are suppressed in quantum dots with small height.
Ownership and production efficiency: Evidence from Taiwanese banks
(2004-07-01)
Li, Y
;
Hu, JL
;
Chiu, YH
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經營管理研究所
;
Institute of Business and Management
In the early 1990s, Taiwan began her deregulation trend in order to enhance competition and economic efficiency across all industries. We derive a theoretical framework to predict possible rankings in technical efficiencies of public, mixed, and private banks. A panel data set with 43 Taiwanese banks during 19971999 is used for empirical analysis. We then apply a translog distance function to estimate technical efficiencies. The relationship between technical efficiency and government shareholding is also examined. Empirical results show that a public bank in Taiwan can improve its technical efficiency by mixed ownership at a diminishing rate. Moreover, banks in Taiwan on average performed worse after the 1997 Asian financial crisis.