Browsing by Author "Wu, HH"

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A methodology for schedule compression
(1996-07-01)
Wu, HH
;
Li, RK
;
交大名義發表
;
工業工程與管理學系
;
National Chiao Tung University
A generated schedule can be improved (especially on due date performance) simply by compressing the current schedule to the left. Additionally, two forms of schedule compression are available, i.e. simple compression and complex compression. In practical considerations, however, knowing exactly where the compression effort should be placed so that the schedule can be improved more efficiently is a relatively difficult task. This decision requires an evaluation methodology, which is the primary objective of this study. The evaluation methodology is based on the priority weight computation for those affected operations. The priority weight computation is an integration of sequence effect weight with time effect weight. The priority weight information provides not only where the compression effort should be placed but also the intelligent information of (1) the operations related to the compression effort and (2) the time that job(s) can be packed to the left. Specifics of the schedule compression concepts and algorithms of the evaluation methodology are also discussed.
A methodology for schedule compression
(1996-07-01)
Wu, HH
;
Li, RK
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
A generated schedule can be improved (especially on due date performance) simply by compressing the current schedule to the left. Additionally, two forms of schedule compression are available, i.e. simple compression and complex compression. In practical considerations, however, knowing exactly where the compression effort should be placed so that the schedule can be improved more efficiently is a relatively difficult task. This decision requires an evaluation methodology, which is the primary objective of this study. The evaluation methodology is based on the priority weight computation for those affected operations. The priority weight computation is an integration of sequence effect weight with time effect weight. The priority weight information provides not only where the compression effort should be placed but also the intelligent information of (1) the operations related to the compression effort and (2) the time that job(s) can be packed to the left. Specifics of the schedule compression concepts and algorithms of the evaluation methodology are also discussed.
Cu-penetration induced breakdown mechanism for a-SiCN
(2004-12-22)
Chen, CW
;
Liu, PT
;
Chang, TC
;
Yang, JH
;
Tsai, TM
We have investigated the leakage mechanism of amorphous SiCN (a-SiCN) films after bias-temperature-stress (BTS) with Cu electrode. The leakage current became very large and breakdown due to the Cu ions penetration after strict BTS condition. The distribution profile of Cu penetration was depicted by SIMS spectrum. It is apparent that Cu ions penetrated into the a-SiCN film and even reached to the interface between a-SiCN/Si due to BTS. The Cu ions existing in a-SiCN would be taken as trap states and could enhance the carriers to transport. The main characteristics of post-breakdown a-SiCN followed the space-charge-limited current (SCLC) mechanism at 298 K. With decreasing the temperature to 100 K, the Fowler-Nordheim tunneling dominated the conduction in medium fields. However, electrons obeyed the SCLC again in high fields (>3.3 MV/cm) at 100 K. We purpose a physical model to interpret the leakage mechanism of breakdown a-SiCN films due to Cu ions. (C) 2004 Elsevier B.V. All rights reserved.
Dark current and trailing-edge suppression in ultrafast photoconductive switches and terahertz spiral antennas fabricated on multienergy arsenic-ion-implanted GaAs
(2005-07-01)
Liu, TA
;
Lin, GR
;
Lee, YC
;
Wang, SC
;
Tani, M
We report ultrafast (similar to 2.7 ps, instrument limited) switching responses of a multienergy- implanted GaAs:As' photoconductive switches (PCSs) with suppressed trailing edge and reduced dark. current. This material is highly resistive with dark current as low as 0.94 mu A at a bias of 40 V. The carrier mobility of the former is similar to 590 cm(2)/V s, resulting in a small-signal optical responsivity of similar to 2 mA/W. Pumped at 100 mW and biased at 80 V, the multienergy-implanted GaAs: As+ PCS exhibits peak response (0.35 V) comparable to the best result of single-energy-implanted ones. The improvement on photoconductive response is crucial for the generation of shorter terahertz emission pulses from spiral antennas fabricated on multienergy-implanted GaAs:As+ (0.8 ps) than single-energy-implanted GaAs (1.2 ps), with the central frequency blueshifted to 0.2 THz (from 0.15 THz) and the spectral bandwidth broadened to 0.18 THz (from 0.11 THz). (c) 2005 American Institute of Physics.
Fabrication of NiSi2 nanocrystals embedded in SiO2 with memory effect by oxidation of the amorphous Si/Ni/SiO2 structure
(2005-07-01)
Yeh, PH
;
Wu, HH
;
Yu, CH
;
Chen, LJ
;
Liu, PT
NiSi2 nanocrystals embedded in the SiO2 layer exhibiting a memory effect have been formed by dry oxidation of an amorphous Si/Ni/SiO2 structure at 900 degrees C. A pronounced capacitance-voltage hysteresis was observed with a memory window of I V under the 2 V programming voltage for the samples. For dry oxidation at 800 degrees C, no distinct memory effect was detected. The processing of the structure is compatible with the current manufacturing technology of the semiconductor industry. The structure represents a viable candidate for low-power nanoscaled nonvolatile memory devices. (c) 2005 American Vacuum Society.
Harmonic mode locking and multiple pulsing in a soft-aperture Kerr-lens mode-locked Ti : sapphire laser
(2002-10-15)
Lin, JH
;
Hsieh, WF
;
Wu, HH
;
光電工程學系
;
Department of Photonics
We report the observation of harmonic mode locking and multiple pulse operations in a soft-aperture Kerr-lens mode-locked Ti:sapphire laser by varying the total intra-cavity dispersion. Second, third, and fourth order harmonic mode locking as well as multiple pulsing with interpulse separation ranging from femtosecond to nanosecond are observed. The laser is characterized in these regimes in terms of wavelength, bandwidth, pulsewidth, average and peak powers as functions of group velocity dispersion. By introducing a loss difference term into gain dynamic analysis, we conclude that gain depletion and recovery mechanisms are responsible for the underlying physics of current observations. (C) 2002 Elsevier Science B.V. All rights reserved.
Leakage behavior of the quasi-superlattice stack for multilevel charge storage
(2004-05-03)
Chang, TC
;
Yan, ST
;
Liu, PT
;
Chen, CW
;
Wu, HH
The leakage behavior of the quasi-superlattice structure has been characterized by current-voltage measurements at room temperature and 50 K. A resonant tunnelinglike leakage characteristic is observed at low temperature. The resonant tunneling occurs at around 2, 5.2, and 7 V under a gate voltage swept from 0 to 10 V. A concise physical model is proposed to characterize the leakage mechanism of tunneling for the quasi-lattice structure and suggests that the considerations of the operating voltage for the two-bit per cell nonvolatile-memory device need to be taken into account. (C) 2004 American Institute of Physics.
Observations of multipass transverse modes in an axially pumped solid-state laser with different fractionally degenerate resonator configurations
(2001-01-01)
Wu, HH
;
Hsieh, WF
;
光電工程學系
;
Department of Photonics
We experimentally show, for the first time to our knowledge, that a diode-pumped Nd:YVO4 laser can operate with multipass transverse (MPT) modes that self-reproduce after several round trips in a plano-concave cavity that has fractionally degenerate resonator configurations when the pump beam waist is sufficiently smaller than that of the fundamental cavity mode. The MPT mode is found to exhibit multiple beam waists located at different positions and to experience a lower pumping threshold than the single-pass transverse mode. With off-axis pumping, the N-pass transverse mode forms a symmetric pattern for even N and an asymmetric pattern for odd N. This result can be explained as being due to the introduction of MPT modes but not to superposition of the standard cavity modes. (C) 2001 Optical Society of America.
Photoconductive generation of short electrical pulses of variable duration using a coplanar waveguide with capacitively coupled ground termination
(2004-05-01)
Wu, HH
;
Liu, JL
;
Pan, CL
;
光電工程學系
;
Department of Photonics
Short electrical pulses with variable duration are generated by optically exciting a coplanar waveguide that is capacitively connected to a ground termination. The underlying concept is based on the superposition of the original pulse and the reflected one with an opposite sign and a variable round trip delay. By sliding the pump beam along the coplanar waveguide, generation of short electrical pulses with different peak voltages, widths, and signs are demonstrated in a laser-diode-based system. (C) 2004 American Institute of Physics.
Quasi-superlattice storage - A concept of multilevel charge storage
(2004)
Chang, TC
;
Yan, ST
;
Liu, PT
;
Chen, CW
;
Wu, HH
this work, a novel concept of quasi-superlattice storage (QS(2)) is demonstrated. Under a suitable operating voltage, two apparent states of charge storage can be distinguished. The memory effects are due to the multilevel charge storage within the quasi-superlattice. The multilevel charge storage provides a feasible design for the 2-bit-per-cell nonvolatile memory devices. Also, the leakage behavior of the quasi-superlattice structure has also been characterized by current-voltage measurements at room temperature and low temperatures. The resonant tunneling-like leakage characteristic is observed at low temperatures. A concise physical model is proposed to characterize the leakage mechanism of tunneling for the quasi-superlattice structure, and this suggests that consideration of the operating voltage for the 2-bit-per-cell nonvolatile memory device needs to be taken into account. (C) 2004 The Electrochemical Society.
Quasisuperlattice storage: A concept of multilevel charge storage
(2004-07-12)
Chang, TC
;
Yan, ST
;
Liu, PT
;
Chen, CW
;
Wu, HH
A concept of the quasisuperlattice storage has been demonstrated in this study. Under suitably operated voltage, two apparent states of charge storage can be distinguished. The memory effects are due to the multilevel storage in the quasisuperlattice. Also, the a-Si quantum wells provide a feasible design for the 2 bit per cell nonvolatile memory devices. The operation of the 2 bit per cell needs to be performed by Fowler-Nordheim tunneling instead of conventional channel hot electron injection. Additionally, the dual read operation of the source and drain sides for conventional SONOS 2 bit/cell device is not necessary, which simplifies the circuit design engineering. (C) 2004 American Institute of Physics.
Resonator configuration dependent nonlinear dynamics with application to Kerr-lens mode-locked lasers
(1999)
Hsieh, WF
;
Wei, MD
;
Wu, HH
;
光電工程學系
;
Department of Photonics
The nonlinear dynamics of the Gaussian beam propagation in resonator was studied by constructing the iterative map of q-parameter. From the Greene's residue theorem, there are specific configurations sensitive to nonlinear effect existing in the geometrically stable region. By applying to Kerr-lens mode-locking (KLM) resonators, we found that multiple solution, period doubling, period tripling and period quadrupling can occur at the configurations with product of cavity G-parameters equal. to 0, 1/2, 1/4 (or 3/4) and (2 +/- root 2)/4, respectively. Moreover, the systems will result in classical chaos if further increasing the nonlinear effect. We will report the appearance of unexpected transverse beam profiles and shrinkage of beam waist causes to lower laser threshold in an end-pumped Nd:YVO4 laser and chaotic behavior in the KLM laser around these critical resonator configurations.
Study on etching profile of nanoporous silica
(2004-12-22)
Chen, CW
;
Chang, TC
;
Liu, PT
;
Tsai, TM
;
Wu, HH
We have investigated the impact of Hz-plasma treatment on porous organosilicate glass (POSG) with etching process. The etching rate of trenches of nanoporous silica film was about 650 nm/min using fluorocarbon plasma. It is 1.6 times the etching rate of CVD oxide for the same etching condition due to the high porosity of POSG. We found that the profile of the intrinsic sample had mask undercutting. By the contrary, the mask undercutting effect was suppressed in the H-2,-plasma-treated sample. Based on the FTIR spectra analysis, the Si-H bonding was appeared after H-2-plasma treatment. The existence of Si-H bonds enhances to possess high C/F ratio and high polymerization rate at the sidewall surface. As a result, the spontaneous reactive etching at sidewall was suppressed. We also observed the pattern profile of porous silica was distorted after O-2-plasma ashing. This is due to the oxidation of hydrophobic groups and the formation of Si-OH bonds in the bulk. The interaction between the siloxanol groups and the gelation reaction occurred in the internal of porous organosilicates predominate stress evolution, leading to the deformation of patterned porous organosilicate films. (C) 2004 Published by Elsevier B.V.
Synthesized high-impedance CMOS thin-film transmission line
(2004)
Wu, HH
;
Wu, HS
;
Tzuang, CKC
;
傳播研究所
;
Institute of Communication Studies
A synthetic quasi-TEM CMOS transmission line (TL) of wide range characteristic impedance from 58.3 to 95 Omega is presented for miniaturization of CMOS RFIC. The synthetic TL consists of unit cells made of complementary-conducting strips (CCS) and connecting arm for signal interface residing on the M5 and M1 metal layers of a typical 0.25 mu m 1P5M CMOS process. Measured results and theoretical data indicate that the loss per guiding Wavelength of the meandered CCS TL is about 13 % lower than that of the meandered microstrip of characteristic impedance 86.4 Omega at 40 GHz.
The detuning characteristics of rational harmonic mode-locked semiconductor optical amplifier fiber-ring laser using backward optical sinusoidal-wave injection modulation
(2005-03-01)
Lin, GR
;
Hsueh, PS
;
Wu, HH
;
Liao, YS
;
光電工程學系
The modulation waveform, power, and frequency detuning dynamics of a semiconductor optical amplifier fiber-ring laser (SOAFL) harmonic and rational-harmonic mode-locked by using backward injection of a large-signal sinusoidal-wave modulated Fabry-Perot laser diode (FPLD) are studied. The shortest pulsewidth of 53.3 ps at 1 GHz with spectral linewidth of 0.09 run at modulation power of 17 dBm can be obtained, which corresponds to a time-bandwidth product of 2.8. The threshold modulation power and the maximum frequency detuning range for harmonic mode-locking of the SOAFL are 11.5 dBm and 180 kHz, respectively. The mode-locked SOAFL gradually recovers back to sinusoidal-wave modulation mode at the detuning frequency beyond +/- 400 kHz. The pulse broadening slopes for the positive- and negative-frequency detuning regions of 0.48 and 0.375 ps/kHz are,determined, respectively. By enlarging the modulating power and detuning the modulation frequency of FPLD, the SOAFL can be rational-harmonic mode-locked up to 12 GHz with 33-ps pulsewidth.