Browsing by Author "Cheng, CT"

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A physically-based built-in Spice Poly-Si TFT model for circuit simulation and reliability evaluation
(1996)
Chung, SS
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Chen, DC
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Cheng, CT
;
Yeh, CF
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交大名義發表
A Poly-Si TFT model for circuit simulation in Spice is presented, combined with a device degradation model for the first time to evaluate the circuit reliability. Both I-V and C-V models for the whole device operating regime have been developed. In the I-V model, emphasis has been taken to derive the mobility degradation induced by the grain boundary potantial barrier height and trap density. The small geometry effect, off-state current and the parasitic BJT effect are also considered in the model. Good agreements between modeled and experimental data were achieved. To evaluate the circuit reliability after electrical stress, the device reliability model has also been developed. Finally, simulation a 27-stage ring oscillator has been demonstrated, which shows delay time of about 1 nsec per stage.
Applications of semiconductor nanoparticles in electron transfer, energy transfer and metal ion recognition.
(2004-08-22)
Chou, YH
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Chiu, HT
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Chen, CY
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Cheng, CT
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Chou, PT
Low-power BIBITS encoding with register relabeling for instruction bus
(2005)
Cheng, CT
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Chiao, WH
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Shann, JJJ
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Chung, CP
;
Chen, WF
Reducing power consumption of embedded system has gained much attention recently. Reducing memory bus switchings is an effective way to reduce system power since memory bus power constitutes a great portion of the system power. While many techniques exist for reducing bus power in address buses, only a few have been proposed for content-bus power reduction. We propose a Bus-Invert and Bus-Invert with transition signaling (BIBITS) encoding scheme to reduce power consumption on instruction bus. An instruction is partitioned into fields according to its format. Four elementary Boolean functions are used as encoding functions. BIBITS uses the most suitable encoding functions for different instruction partitions. We also propose a register relabeling algorithm for BIBITS encoding to further reduce bit switchings on register fields. Simulation results show that the overall average switching reduction is 64% of unencoded bus, 59% of the previous register relabeling scheme, and 33% of Petrov's bus encoding scheme. Compared with Petrov's bus encoding scheme, our scheme uses a decoding signal table only half the size to encode all basic blocks.
Potassium ion recognition by 15-crown-5 functionalized CdSe/ZnS quantum dots in H2O
(2006-01-21)
Chen, CY
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Cheng, CT
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Lai, CW
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Wu, PW
;
Wu, KC
Based on 15-crown-5 functionalized CdSe/ZnS quantum dots (QDs), we report a novel fluorogenic sensor to probe K+ ions in H2O; recognition of K+ can be achieved via the Forster type of energy transfer between two different color QDs, so that [K+] of the order of 10(-6) M can be promptly detected.
Seismic behavior of steel beam and reinforced concrete column connections
(2005-05-01)
Cheng, CT
;
Chen, CC
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土木工程學系
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Department of Civil Engineering
This paper aims to investigate the seismic behavior of steel beam to reinforced concrete column connections with or without the floor slab, acting as a proof test for a three-story-three-bay reinforced concrete column and steel beam (RCS) in-plane frame tested at the National Center for Research on Earthquake Engineering (NCREE), Taiwan, by the Taiwan-USA international research cooperation group. In total, six cruciform RCS joint sub-assemblages were constructed and tested. Parameters considered included composite effects of the slab and beam, the tie configuration in the panel zone, effects of the cross-beam, and the loading protocol. Force-deformation behavior was also simulated by a nonlinear analysis program, DRAIN-2DX, with consideration of composite effects of the beam and slab as well as shear distortion in the panel zone. Test results showed that all specimens performed in a ductile manner with plastic hinges formed in the beam ends near the column face. It was found that the ultimate strength of the composite beam was increased by 27% on average, compared with that of the steel beam without the slab. (C) 2004 Elsevier Ltd. All rights reserved.
Spectroscopy and femtosecond dynamics of type-II CdSe/ZnTe core-shell semiconductor synthesized via the CdO precursor
(2004-07-29)
Chen, CY
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Cheng, CT
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Yu, JK
;
Pu, SC
;
Cheng, YM
CdSe/ZnTe type-II quantum dots (QDs) synthesized via the CdO precursor are reported. Spectroscopic and femtosecond dynamic measurements reveal that the rate of photoinduced electron/hole spatial separation decreases with increases in the size of the core, and it is independent of the thickness of the shell in the CdSe/ZnTe QDs. The results are consistent with the binding strength of the electron and hole confined at the center of CdSe. The correlation between the core/shell size and the electron/hole spatial separation rate resolved in this study may provide valuable information for applications where rapid photoinduced carrier separation followed by charge transfer into a matrix or electrode is crucial, such as in photovoltaic devices.
Spectroscopy and femtosecond dynamics of type-II CdTe/CdSe core-shell quantum dots
(2006-01-16)
Chou, PT
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Chen, CY
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Cheng, CT
;
Pu, SC
;
Wu, KC
Syntheses of CdTe/CdSe type-II quantum dots (QDs) using CdO and CdCl2, as precursors for core and shell, respectively, are reported. Characterization was made via near-IR interbond emission, transmission electron microscopy (TEM), energy dispersive spectroscopy (EDX), and X-ray diffraction (XRD). Femtosecond fluorescence upconversion measurements on the relaxation dynamics of the CdTe core (in CdTe/CdSe) emission and CdTe/CdSe inter-band emission reveal that as the size of the core increases from 5.3, 6.1 to 6.9 nm, the rate of photoinduced electron separation decreases from 1.96, 1.44 to 1.07 X 10(12) s(-1). The finite rates of the initial charge separation ore tentatively rationalized by the small electron-phonon coupling, causing weak coupling between the initial and charge-separated states.
Syntheses and photophysical properties of type-II CdSe/ZnTe/ZnS (core/shell/shell) quantum dots
(2005)
Cheng, CT
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Chen, CY
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Lai, CW
;
Liu, WH
;
Pu, SC
Syntheses of CdSe/ ZnTe/ ZnS (core/shell/shell) type-II quantum dots (QDs) are reported. Structural characterization was made via TEM, EDX, XPS and XRD. Photophysical properties were investigated via the interband emission (CdSe -> ZnTe) and its associated quantum efficiency as well as relaxation dynamics. In comparison to the weak emission (Phi(f) similar to 4 x 10(-3) in toluene) of CdSe/ ZnTe (3.9/ 0.5 nm), capping ZnS (0.4 nm in thickness) enhances the CdSe -> ZnTe interband emission by similar to 30 fold (Phi(f) similar to 0.12), whereas the peak wavelength shifts only slightly to the red. By encapsulating dihydrolipoic acid ( DHLA), water-soluble CdSe/ ZnTe/ ZnS QDs were also prepared, and they exhibited an interband emission at y930 nm with an emission yield of similar to 0.1. Femtosecond pulse excitation (lambda(ex) similar to 1200 nm) measurement estimated a two- photon absorption cross section, sigma, of similar to 70 x 10(-50) cm(4) s photon(-1) for DHLA-capped CdSe/ ZnTe/ ZnS in water, supporting its suitability for the use as near-infrared (NIR) dyes in biomedical imaging.
Type-II CdSe/CdTe/ZnTe (core-shell-shell) quantum dots with cascade band edges: The separation of electron (at CdSe) and hole (at ZnTe) by the CdTe layer
(2005-12-01)
Chen, CY
;
Cheng, CT
;
Lai, CW
;
Hu, YH
;
Chou, PT
The rational design and synthesis of CdSe/CdTe/ZnTe (core-shell-shell) type-II quantum dots are reported. Their photophysical properties are investigated via the interband CdSe -> ZnTe emission and its associated relaxation dynamics. In comparison to the strong CdSe (core only) emission (lambda(max) approximate to 550 nm, Phi(f) approximate to 0.28), a moderate CdSe -> Cd Te emission (lambda(max) approximate to 1026 nm, Phi(f) approximate to 1.2 x 10(-3)) and rather weak CdSe -> Zn Te interband emission (lambda(max) approximate to 1415 nm, Phi(f) approximate to 1.1 x 10(-5)) are resolved for the CdSe/CdTe/ ZnTe structure (3.4/1.8/1.3 nm). Capping CdSe/CdTe with ZnTe results in a distant electron-hole separation between CdSe (electron) and ZnTe (hole) via an intermediate CdTe layer In the case of the CdSe/CdTe/ ZnTe structure, a lifetime as long as 150 ns is observed for the CdSe -> Zn Te (1415 nm) emission. This result further indicates an enormously long radiative lifetime of approximate to 10 ms. Upon excitation of the CdSe/CdTe/ Zn Te structure, the long-lived charge separation may further serve as an excellent hole carrier for catalyzing the redox oxidation reaction.