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- Huang, Yue, et al.
(författare)
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Memory Effect of Metal-Oxide-Silicon Capacitors with Self-Assembly Double-Layer Au Nanocrystals Embedded in Atomic-Layer-Deposited HfO2 Dielectric
- 2009
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Ingår i: Chinese Physics Letters. - 0256-307X .- 1741-3540. ; 26:10
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Tidskriftsartikel (refereegranskat)abstract
- We report the chemical self-assembly growth of Au nanocrystals on atomic-layer-deposited HfO2 films aminosilanized by (3-Aminopropyl)-trimethoxysilane aforehand for memory applications. The resulting Au nanocrystals show a density of about 4 x 10(11) cm(-2) and a diameter range of 5-8 nm. The metal-oxide-silicon capacitor with double-layer Au nanocrystals embedded in HfO2 dielectric exhibits a large C - V hysteresis window of 11.9 V for +/- 11 V gate voltage sweeps at 1 MHz, a flat-band voltage shift of 1.5 V after the electrical stress under 7 V for 1 ms, a leakage current density of 2.9 x 10(-8) A/cm(-2) at 9 V and room temperature. Compared to single-layer Au nanocrystals, the double-layer Au nanocrystals increase the hysteresis window significantly, and the underlying mechanism is thus discussed.
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| 2. |
- Liao, Zhong-Wei, et al.
(författare)
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Robust Low Voltage Program-Erasable Cobalt-Nanocrystal Memory Capacitors with Multistacked Al2O3/HfO2/Al2O3 Tunnel Barrier
- 2009
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Ingår i: Chinese Physics Letters. - 0256-307X .- 1741-3540. ; 26:8, s. 087303-
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Tidskriftsartikel (refereegranskat)abstract
- An atomic-layer-deposited Al2O3/HfO2/Al2O3 (A/H/A) tunnel barrier is investigated for Co nanocrystal memory capacitors. Compared to a single Al2O3 tunnel barrier, the A/H/A barrier can significantly increase the hysteresis window, i. e., an increase by 9V for +/- 12V sweep range. This is attributed to a marked decrease in the energy barriers of charge injections for the A/H/A tunnel barrier. Further, the Co-nanocrystal memory capacitor with the A/H/A tunnel barrier exhibits a memory window as large as 4.1V for 100 mu s program/erase at a low voltage of +/- 7V, which is due to fast charge injection rates, i. e., about 2.4 x 10(16) cm(-2) s(-1) for electrons and 1.9 x 10(16) cm(-2) s(-1) for holes.
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| 8. |
- Sicular, Terry, et al.
(författare)
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The Urban-Rural Income Gap and Inequality in China
- 2007
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Ingår i: Review of Income and Wealth. - 1475-4991. ; 53:1, s. 93-126
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Tidskriftsartikel (refereegranskat)abstract
- Using new and rich data for 1995 and 2002, this study investigates the size of China’s urban-rural income gap, the contribution of that gap to overall inequality in China, and the factors underlying the gap. The analysis improves on past estimates by adjusting for spatial price differences and including migrants. Methods employed include inequality decomposition by population subgroup and the Oaxaca-Blinder decomposition method. Several key findings emerge. First, most estimates of China’s urban-rural income gap and its contribution to overall inequality may be substantially overstated. Second, the Oaxaca-Blinder decomposition reveals that after controlling for household and individual characteristics, location of residence remains the most important factor underlying the urban-rural income gap. The only household characteristic that contributes substantially to the gap is education. Differences in the endowments of, and returns to, other household characteristics such as family size and composition, landholdings, and Party membership are relatively unimportant.
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| 9. |
- Tang, Liqiu, et al.
(författare)
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A zeolite family with chiral and achiral structures built from the same building layer
- 2008
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Ingår i: Nature Materials. - : Springer Science and Business Media LLC. - 1476-1122 .- 1476-4660. ; 7:5, s. 381-385
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Tidskriftsartikel (refereegranskat)abstract
- Porosity and chirality are two of the most important properties for materials in the chemical and pharmaceutical industry. Inorganic microporous materials such as zeolites have been widely used in ion-exchange, selective sorption/separation and catalytic processes. The pore size and shape in zeolites play important roles for specific applications(1-3). Chiral inorganic microporous materials are particularly desirable with respect to their possible use in enantioselective sorption, separation and catalysis(4). At present, among the 179 zeolite framework types reported, only three exhibit chiral frameworks(5-7). Synthesizing enantiopure, porous tetrahedral framework structures represents a great challenge for chemists. Here, we report the silicogermanates SU-32 (polymorph A), SU-15 (polymorph B) (SU, Stockholm University) and a hypothetical polymorph C, all built by different stacking of a novel building layer. Whereas polymorphs B and C are achiral, each crystal of polymorph A exhibits only one hand and has an intrinsically chiral zeolite structure. SU-15 and SU-32 are thermally stable on calcination.
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| 12. |
- Zeng, Qiao-Shi, et al.
(författare)
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Substitutional alloy of Ce and Al
- 2009
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 106:8, s. 2515-2518
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Tidskriftsartikel (refereegranskat)abstract
- The formation of substitutional alloys has been restricted to elements with similar atomic radii and electronegativity. Using high-pressure at 298 K, we synthesized a face-centered cubic disordered alloy of highly dissimilar elements (large Ce and small Al atoms) by compressing the Ce3Al intermetallic compound > 15 GPa or the Ce3Al metallic glass > 25 GPa. Synchrotron X-ray diffraction, Ce L-3-edge absorption spectroscopy, and ab initio calculations revealed that the pressure-induced Kondo volume collapse and 4f electron delocalization of Ce reduced the differences between Ce and Al and brought them within the Hume-Rothery (HR) limit for substitutional alloying. The alloy remained after complete release of pressure, which was also accompanied by the transformation of Ce back to its ambient 4f electron localized state and reversal of the Kondo volume collapse, resulting in a non-HR alloy at ambient conditions.
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