Browsing by Author "Lin, YK"

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An orthogonal simulated annealing algorithm for large floorplanning problems
(2004-08-01)
Ho, SY
;
Ho, SJ
;
Lin, YK
;
Chu, WCC
;
生物科技學系
The conventional simulated annealing with some random generation mechanism using the sequence-pair topological representation in block placement and floorplanning is effective for a very small number of modules (40-50). This paper proposes an orthogonal simulated annealing algorithm (OSA) with an efficient generation mechanism (EGM) for solving large floorplanning problems. EGM samples a small number of representative floorplans and then efficiently derives a high-performance floorplan by using a systematic reasoning method for the next move of OSA based on orthogonal experimental design. Furthermore, an improved swap operation is proposed which cooperates with EGM to make OSA efficient. Excellent experimental results using the Microelectronics Center of North Carolina and the Gigascale Sysems Research Center benchmarks show that OSA performs better than existing methods for large floorplanning problems.
Ballistic transport through coupled T-shaped quantum wires
(2004-05-01)
Lin, YK
;
Lin, KC
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Chuu, DS
;
電子物理學系
;
Department of Electrophysics
The ballistic conductance of a coupled T-shaped semiconductor quantum wire (CTQW) is studied. Two types of CTQW are considered, one of which is a H-shaped quantum wire (PiQW) which consists of two vertical arms on the same side of the horizontal arm and the other a Pi-clone quantum wire (PiCQW) which consists of two vertical armes on the opposite sides of the horizontal arm. The mode matching method and Landauer-Buttiker theory are employed to study the energy dependence of the ballistic conductance. Most of transmission profiles of PiQW and PiCQW are found to be distinguishable for large separation d between the two vertical arms. The transmission probability manifests oscillatory behavior when d is increased. When a potential is applied to the connection region, it results in decoupling or coupling effects between the two T-shaped quantum wires according to whether it is positive or negative. When magnetic field is applied to CTQW, the transmission profiles are found to be affected prominently even if the electron passes through the field free region only. (C) 2003 Elsevier B.V. All rights reserved.
Bound state of the quantum dot formed at intersection of L- or T-shaped quantum wire in inhomogeneous magnetic field
(2002-03-01)
Lin, YK
;
Chen, YN
;
Chuu, DS
;
電子物理學系
;
Department of Electrophysics
A quantum dot (QD) can be formed at the intersection of the symmetric or asymmetric L-shaped (LQW) or T-shaped quantum wire (TQW). The bound state energies in such QD systems surrounded by inhomogeneous magnetic fields are found to depend strongly on the asymmetric parameter alpha=W-2/W-1, i.e., the ratio of the arm widths and magnetic field applied on the wire arms. Two effects of the magnetic field on the bound state energy of the electron can be obtained. One is the depletion effect which purges the electron out of the QD system. The other is to create an effective potential due to the quantized Landau levels of the magnetic field. Depletion effect is found to be more prominent in weak field region. Our results show the bound state energy of the electron in such QD system depends quadratically (linearly) on the magnetic field in the weak (strong) field region. It is also found that the bound state energy of the electron depends on the magnetic field strength only and not on its direction. A simple model is proposed to explain the behavior of the magnetic dependence of the bound state energy of the electron both in weak and strong magnetic field regions. The contour plots of the relative probability of the bound state in LQW or TQW in magnetic field are also presented. (C) 2002 American Institute of Physics.
Bound states of L- or T-shaped quantum wires in inhomogeneous magnetic fields
(2001-11-15)
Lin, YK
;
Chen, YN
;
Chuu, DS
;
電子物理學系
;
Department of Electrophysics
The bound-state energies of L- or T-shaped quantum wires in inhomogeous magnetic fields are found to depend strongly on the asymmetric parameter alpha = W-2/W-1, i.e, the ratio of the arm widths. Two effects of magnetic field on bound-state energies of the electron are obtained. One is the depletion effect, which purges the electron out of the OQD system. The other is to create an effective potential due to quantized Landau levels of the magnetic field. The bound-state energies of the electron in L- or T-shaped quantum wires are found to depend quadratically (linearly) on the magnetic field in the weak- (strong-) field region and are independent of the direction of the magnetic field. A simple model is proposed to explain the behavior of the magnetic dependence of the bound-state energy in both weak- and strong-magnetic field regions.
Characteristics of transmission of electrons in a bent quantum waveguide with inhomogeneous magnetic fields
(1999-07-15)
Gu, BY
;
Lin, YK
;
Chuu, DS
;
電子物理學系
;
Department of Electrophysics
We present numerical studies of the transmission properties in an L-shaped quantum waveguide (LQW) subject to an inhomogeneous magnetic field perpendicular to the LQW plane. The magnetic field remains zero at the corner region, thus, a magnetically defined cavity is formed in this LQW. We find that transmission characteristics of electrons in the LQW depend strongly on geometric parameters and magnetic configurations. Sharp peaks with unity amplitude and deep dips are observed in transmission as a function of the Fermi energy of the incident electron at some high fields. The mode-mode coupling between the wires and the cavity and multiple reflection of electrons in the cavity lead to the appearance of these structures in transmission spectrum. We also study the variation of transmission with magnetic field for different magnetic confinement configurations when fixing incident electron energy. In the magnetic depletion process of the propagating modes in wires, the transmission exhibits various patterns, such as stepped drop, wide valley, deep dips, large oscillations, or without any structure, sensitively dependent on incident electron energy and magnetic confinement configurations. It is expected that one can flexibly modify transmission spectrum of the LQW by applying an inhomogeneous magnetic field to match practical requirements. (C) 1999 American Institute of Physics. [S0021-8979(99)05714-X].
Collective excitations in a single-layer carbon nanotube
(1996-06-15)
Lin, MF
;
Chuu, DS
;
Huang, CS
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Lin, YK
;
Shung, KWK
The inter-pi-band response function of a single-layer carbon nanotube is calculated within the random-phase approximation. Such a cylindrical system exhibits rich inter-pi-band excitations. The decoupled pi plasmons;of different angular momenta (L's) strongly depend on the transferred momenta (q's). Furthermore, they exhibit a dimensionality crossover as the nanotube radius is increased. For small q's and L's, the pi plasmon frequency is similar to 6-8 eV, which is insensitive to the nanotube geometry such as the radius and chiral angle. Comparison with recent experiments is discussed.
Effect of electron-phonon interaction on the impurity binding energy in a quantum wire
(2000-09-01)
Chuu, DS
;
Chen, YN
;
Lin, YK
;
電子物理學系
;
Department of Electrophysics
The effect of electron-optical phonon interaction on the hydrogenic impurity binding energy in a cylindrical quantum wire is studied. By using Landau and Pekar variational method, the Hamiltonian is separated into two parts which contain phonon variable and electron variable, respectively. A perturbative-variational technique is then employed to construct the trial wave function for the electron part. The effect of confined electron-optical phonon interaction on the binding energies of the ground state and an excited state are calculated as a function of wire radius. Both the electron-bulk optical phonon and electron-surface optical phonon coupling are considered. It is found that the energy corrections of the polaron effects on the impurity binding energies increase rapidly as the wire radius is shrunk, and the bulk-type optical phonon plays the dominant role for the polaron effects. (C) 2000 Elsevier Science B.V. All rights reserved.
Fast block type decision algorithm for intra prediction in H.264 FRext
(2005)
Lin, YK
;
Chang, TS
;
電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
This paper presents a fast block type decision algorithm for 4x4, M and 16x16 intra prediction in H.264/AVC FRExt (Fidelity Range Extension). With additional M intra prediction size, the complexity of intra prediction is increased by almost 50%. Thus, the proposed algorithm uses the smoothness of the macroblock to select the intra prediction block size and save computational cost. When further combining with our previously proposed three-step fast intra prediction algorithm, the proposed algorithm can save up to 32.1% and 63.4% of computation time of all I frames and intra prediction coding respectively, and achieves average 1.05% bit rate decrease and 0.046 dB quality degradation when comparing with the reference software.
Novel strategies of FSG-CMP for within-wafer uniformity improvement and wafer edge yield enhancement beyond 0.18 micro technologies
(2001)
Chen, KW
;
Wang, YL
;
Chang, L
;
Liu, CW
;
Lin, YK
The low-K films and higher multiple stacked layers would be widely applied for ultra large-scale integrated circuits [1][2]. However for 8" (200mm) or 12" (300mm) wafer the phenomena of wafer edge collapsing in higher interlayer low-K dielectric film causes from CMP polishing effect. (Shown in Fig. 1). Conventionally a amount of work has been developed in the optimization of different parameters, such as low pressure and high speed [3], metal dummy filling [4], harder pad used [4], and design of polishing head in order to resolve the problems. But these methods only engaged in design of experiment, not addressed in CMP theory of edge collapsing and controlling way. In this paper we will discuss the theory applied in Preston equation to explain the polishing behavior in wafer edge. In advance, to implement the theory, we adopted novel strategies, including of different polishing head (sweep) vibration and pad edge sprayer methods, even new wafer retaining ring design and novel delivery slurry methods in advance. The characteristics of within wafer nonuniformity and edge profile against CMP polishing low-k films, fluorinated silicate glass (FSG), would be evaluated in this new strategy action. Besides, the dimension of metal line and VIA, and edge die-yield can be directly responded to the edge profile improvement. From the action results, the average 7 similar to 10% yield improvement of 0.18 technology can be achieved, especially 15% edge-die yield improvement. The edge profile could promote the phenomena of no collapsing from the original 75 mm to 95 mm of wafer center-to-edge distance, excluding 3 mm edge of 8-inch wafer. These high efficient strategies for within-wafer planarization and edge profile is also proven and fulfilled with the reducing over 50% VIA CD deviation on the rule of lithography.
The effect of electron-phonon interaction on the impurity binding energy in a quantum well
(1999-10-25)
Chen, YN
;
Chuu, DS
;
Lin, YK
;
電子物理學系
;
Department of Electrophysics
The effect of confined electron-optical phonon interaction on the hydrogenic impurity binding energy in a quantum well is studied. By using the Landau and Pekar variational method, the Hamiltonian is separated into two parts which contain phonon variables and electron variables. A perturbative-variational technique is then employed to construct the trial wave function for the electron part. The effects of electron-optical phonon interaction on the binding energies are calculated as functions of the well width. In the study of the polaron effects on the impurity binding energies in a quantum well, both confined bulk optical phonon and surface optical phonon effects are taken into account. It is found that the surface phonon effect prevails over the bulk phonon effect when the well width is small. The polaron effects on lower-lying excited states are also calculated. The line strengths of transitions from the ground state to lower-lying excited states are calculated as functions of the donor position and the well width.
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.