Browsing by Author "Chen, S. C."

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A computational study on the kinetics and mechanism for the unimolecular decomposition of o-nitrotoluene
(2006-08-24)
Chen, S. C.
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Xu, S. C.
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Diau, E.
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Lin, M. C.
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應用化學系分子科學碩博班
The kinetics and mechanism for the unimolecular decomposition of o-nitrotoluene (o-CH3C6H4NO2) have been studied computationally at the G2M(RCC, MP2)//B3LYP/6-311G(d, p) level of theory in conjunction with rate constant predictions with RRKM and TST calculations. The results of the calculations reveal 10 decomposition channels for o-nitrotoluene and its six isomeric intermediates, among them four channels give major products: CH3C6H4 + NO2, C6H4C(H) ON (anthranil) + H2O, CH3C6H4O (o-methyl phenoxy) + NO, and C6H4C(H-2) NO + OH. The predicted rate constants in the 500-2000 K temperature range indicate that anthranil production, taking place initially by intramolecular H-abstraction from the CH3 group by NO2 followed by five-membered ring formation and dehydration, dominates at temperatures below 1000 K, whereas NO2 elimination becomes predominant above 1100 K and CH3C6H4O formation by the nitro-nitrite isomerization/decomposition process accounts for only 5-11% of the total product yield in the middle temperature range 800-1300 K. The branching ratio for CH2C6H4NO formation by the decomposition process of CH2C6H4N(O)OH is negligible. The predicted high-pressure-limit rate constants with the rate expression of 4.10 x 10(17) exp[-37000/T] s(-1) for the NO2 elimination channel and 9.09 x 10(12) exp[-25800/T] s(-1) for the H2O elimination channel generally agree reasonably with available experimental data. The predicted high-pressure-limit rate constants for the NO and OH elimination channels are represented as 1.49 x 10(14) exp[-30000/T] and 1.31 x 10(15) exp[-38000/T] s(-1), respectively.
HfSiON n-MOSFETs using low-work function HfSi chi gate
(2006-09-01)
Wu, C. H.
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Hung, B. F.
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Chin, Albert
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Wang, S. J.
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Yen, F. Y.
The authors have developed a novel high-temperature stable HfSix gate for high-kappa HfSiON gate dielectric. After a 1000 degrees C RTA, the HfSix/HfSiON devices showed an effective work function of 4.27 eV and a peak electron mobility of 216 cm(2)/V (.) s at 1.6-nm equivalent oxide thickness, with additional merit of a process compatible with current very large scale integration fabrication lines.
High temperature stable [Ir3Si-TaN]/HfLaON CMOS with large work-function difference
(2006)
Wu, C. H.
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Hung, B. F.
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Chin, Albert
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Wang, S. J.
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Chen, W. J.
We report novel 1000 degrees C-stable [Ir3Si-TaN]/HfLaON CMOS for the first time, where the self-aligned and gate-first process are full compatible to current VLSI. Good phi(m.eff) of 5.08 and 4.24 eV, low V, of -0.10 and 0.18 V, high mobility of 84 and 217 cm(2)/Vs at 1.6 nm EOT, and small 850 degrees C BTI < 20 mV (10 MV/cm for 1 hr) are measured.
High-temperature stable HfLaON p-MOSFETs with high-work-function Ir3Si gate
(2007-04-01)
Wu, C. H.
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Hung, B. F.
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Chin, Albert
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Wang, S. J.
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Wang, X. P.
We report a novel 1000 degrees C stable HfLaON p-MOSFET with Ir3Si gate. Low leakage current of 1.8 x 10(-5) A/cm(2) at 1 V above flat-band voltage, good effective work function of 5.08 eV, and high mobility of 84 cm(2)/V center dot s are simultaneously obtained at 1.6 nm equivalent oxide thickness. This gate-first p-MOSFET process with self-aligned ion implant and 1000 degrees C rapid thermal annealing is fully compatible to current very large scale integration fabrication lines.
Microstructure and magnetic properties of oxidized titanium nitride thin films in situ grown by pulsed laser deposition
(2013-02-20)
Chen, S. C.
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Sung, K. Y.
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Tzeng, W. Y.
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Wu, K. H.
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Juang, J. Y.
Different oxidation states of titanium nitride thin films, including pure TiN(h 0 0), TiN1-xOx(h 0 0), Ti2O3(0 0 l) and pure anatase TiO2(0 0 l), were prepared by pulsed laser deposition with various oxygen pressures (P-O2) using a TiN target. Elaborative evolutions of the crystal and electronic structures of the obtained films were examined systematically by x-ray diffraction and x-ray absorption spectroscopy. We found that the Ti2O3(0 0 l) film, which was prepared at oxygen pressures P-O2 = 10(-4) Torr, exhibited the maximum room temperature ferromagnetism (RTFM) behaviour. The bound magnetic polaron model is used to clarify the origin of RTFM in these films.
Perturbed hydrogen permeation of a hydrogen mixture - New phenomena in hydrogen permeation by Pd membrane
(2008-04-01)
Chen, S. C.
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Hung, Caryat C. Y.
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Tu, G. C.
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Rei, M. H.
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材料科學與工程學系
The newly developed constant concentration method was adopted to study the hydrogen permeation of a hydrogen mixture of H-2 + Y through a palladium membrane tube. The hydrogen permeation of the hydrogen mixture differs from that of a single hydrogen feed. For the hydrogen mixture, the well-known Sieverts equation, Q = J(H)/[(P-R(H))(1/2) - (P-P(H))(1/2)] fails to yield the correct hydrogen flux or permeance even after the pressure terms are adjusted to the partial pressure of hydrogen. The hydrogen concentration in the mixture affects both the flux and the permeance. Significant abnormal permeation of the non-hydrogen gas, Y, in the hydrogen permeates is detected during the hydrogen permeation of the mixture, H-2 + Y, even though Y-gas alone does not permeate through the defect-free palladium membrane. This Y-gas slippage in the presence of hydrogen in the mixture is tentatively attributed to the expansion of the palladium atomic lattice, enlarging inter-cluster openings. Y-gas permeates through the enlarged structure or grain boundary of the palladium atoms in the membrane. The permselectivity of a palladium membrane cannot be measured simply from the ratio of two separate permeation fluxes of H-2 and Y The permselectivity of a hydrogen mixture, H-2 + Y, measured by the constant concentration method in the retentate, is compared with that measured by the flowing-through method and with that determining from two separate measurements of H-2 and of Y. The three methods give different permselectivities of the same palladium membrane tube when the concentration ratio of H-2/Y is adjusted to 1. (C) 2008 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.
Preparation of palladium membrane by electroplating on AISI 316L porous stainless steel supports and its use for methanol steam reformer
(2008-04-30)
Chen, S. C.
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Tu, G. C.
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Hung, Caryat C. Y.
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Huang, C. A.
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Rei, M. H.
A novel electroplating method of preparing Pd-membrane on an AISI 316L porous stainless steel support is successfully developed by proper control of rotation speed of the support. The use of low-current density with high-rotation speed enables us to avoid hydrogen absorption during electroplating and to prepare smooth thin surfaced membrane with defect free. The electroplated-Pd-membrane shows well property in the hydrogen permeation, flux and excellent permselectivity (H-2/He > 100,000), and is used in a membrane-assisted steam reformer of methanol for the production of high-purity hydrogen. It was also found that the membrane spontaneously exhibited to resist hydrogen embrittlement under the phase-transition temperature of 280 degrees C, when operated in the temperature range of 250-350 degrees C under the hydrogen pressure of 9 kgf/cm(2). (C) 2008 Elsevier B.V. All rights reserved.
Relaxation-free strained SiGe with super anneal for 32nm high performance PMOS and beyond
(2006)
Yu, Ming H.
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Li, J. H.
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Lin, H. H.
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Chen, C. H.
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Ku, K. C.
The interaction of epitaxially strained SiGe and super annealing or millisecond anneal in high performance PFET fabrication was, for the first time, systematically investigated. When super annealing was applied, the quality of SiGe/Si interface, affected by subsequent ion implantation and post-SiGe thermal treatment, played an important role in SiGe strain relaxation incurring channel stress loss and defect injection to Si substrate resulting in high junction leakage. Defect injection mechanism was proposed to explain the defect formation in Si substrate. The new processing scheme, which preserved SiGe as relaxation-free and avoided defect injection, was developed and for 32nm technology. The device performance gain with 10% Id,sat increment resulting from fully strained SiGe was achieved.
Study of a Nanoparticle Charger Containing Multiple Discharging Wires in a Tube
(2008)
Tsai, C. J.
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Chen, S. C.
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Chen, H. L.
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Chein, H. M.
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Wu, C. H.
A unipolar charger containing multiple discharging wires in a tube (inner diameter: 50mm) was developed and tested in order to increase the aerosol flow rate and the charging efficiency of nanoparticles. Four gold wires of 25 mm in diameter and 15 mm in length were used as the discharging electrodes to generate positive ions (Ni) from 2.72 x 10(8) ions/cc to 3.87 x 10(9) ions/cc in concentration at the discharging voltage of + 4.0 similar to + 10 KV. Monodisperse NaCl particles of 10 similar to 50nm in diameter were used to test the charging efficiency and the particle loss of charged particles with different aerosol flow rates, corona voltages and sheath flow rates. The sheath air near the tube wall was found to increase the extrinsic charging efficiency, and the highest efficiency was obtained at + 6.0KV discharging voltage, 10 L/min aerosol flow rate and 9 L/min sheath flow rate. The extrinsic charging efficiency increased from 10.6% to 74.2% when the particle diameter was increased from 10 to 50 nm. The TDMA (tandem differential mobility analyzer) method was used to determine the charge distribution and the mean charge per particle and it was found that the Fuchs charging theory corrected for the extrinsic charging efficiency matched with the experimental data very well.
Ultrafast Pump-probe Spectroscopy of Carrier Relaxation Dynamics in Cu(In,Ga)Se-2 Thin Films
(2012)
Chen, S. C.
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Liao, Y. G.
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Chen, H. J.
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Kuo, H. C.
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Wu, K. H.
Ultrafast pump-probe spectroscopy of Cu(In,Ga)Se-2 thin films was performed. We have found the non-radiative recombination dominated at room temperature. It could correlate to efficiency of Cu(In,Ga)Se-2-based solar cells.