Browsing by Author "Hsu, Chia-Jung"

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Characterization of the charge trapping properties in p-channel silicon-oxide-nitride-oxide-silicon memory devices including SiO2/Si3N4 interfacial transition layer
(2015-10-01)
Chiu, Yung-Yueh
;
Yang, Bo-Jun
;
Li, Fu-Hai
;
Chang, Ru-Wei
;
Sun, Wein-Town
The role of SiO2/Si3N4 interfacial transition (IFT) layer in the oxide-nitride-oxide (ONO) tri-layer is quantitatively analyzed for the first time by simulating the temperature and stress-accelerated retention characteristics of p-channel silicon-oxide-nitride-oxide-silicon (SONOS) devices. The ONO tri-layer is modeled as an alloy-dielectric by changing the atomic concentration of silicon, oxygen and nitrogen. It is revealed that simulated results including the IFT layer are more consistent with the experimental data than those neglecting the IFT layer. In addition, the results show that the trapped charge density in IFT layer is two times larger than in the bulk Si3N4 film, due to the oxygen atoms penetrated from SiO2 cause the extrinsic defects in the IFT layer. The energy levels of the trapped charge are continuously distributed, and the peak value is similar to 1.6 eV below the conduction band of the ONO tri-layer with a full width at half maximum of 0.45 eV. (c) 2015 The Japan Society of Applied Physics
Efficient hydrogen production using Cu-based catalysts prepared via homogeneous precipitation
(2009)
Lin, Yu-Kai
;
Su, Yi-Han
;
Huang, Yun-Hsin
;
Hsu, Chia-Jung
;
Hsu, Yu-Kuei
We report here preparation of multi-composition Cu/ZnO/Al(2)O(3) (CZA) catalyst by homogeneous precipitation (HP) method using urea treatment. Compared to the conventional co-precipitation (CP) method, the HP method used here improves the uniformity of metal mixing through homogeneous generation of hydroxide ions as a result of hydrolysis of urea in the solution. In this study, optimization of the conditions to prepare CZA catalyst was achieved by adjusting the urea concentration, amount of water, reaction temperature and reaction time; to control the pH value. The HP-derived CZA particles exhibited a characteristic flower-like morphology with a higher surface area, typically 78.5 m(2)/g as measured by the BET analysis, as compared to the CP-derived CZA catalysts. Induction coupled plasma and energy dispersive spectroscopy mapping results further confirmed the homogeneity of HP-CZA components and highly uniform dispersion of the active metal. Significantly lowering and a narrower range of the reduction temperature for HP-CZA is observed. An improved performance in methanol reforming reaction, in terms of methanol conversion, yield of hydrogen production, and higher carbon dioxide selectivity, has been achieved. Furthermore, the concentration of carbon monoxide can be further reduced by employing CeO(2) and ZrO(2) to modify the support, which also results in reduced reduction temperature and improved performance. Among the modified catalysts, HP-CZCZ catalyst showed the highest methanol conversion and rate of hydrogen production, simultaneously with reduced concentration of CO. Moreover, only 20 mg of catalyst loading yielded 98% methanol conversion rate under more than 8500 h(-1) GHSV. In future, not only can this method be used to synthesize other multi-composition materials with high homogeneity, but also our approach presents opportunity for production of a highly active catalyst for efficient generation of hydrogen for fuel cell applications.