Browsing by Author "Liu, Fu-Ken"

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A Robust Data Retention Characteristic of Sol-Gel-Derived Nanocrystal Memory by Hot-Hole Trapping
(2010-07-01)
Wu, Chi-Chang
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Ko, Fu-Hsiang
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Yang, Wen-Luh
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You, Hsin-Chiang
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Liu, Fu-Ken
A new sol-gel-derived Ti(x)Zr(y)Si(z)O nanocrystal (NC) memory with a high-performance data retention characteristic is demonstrated by the hot-hole-trapping method. Prior to rapid thermal annealing, the high-density NC layer is formed by depositing a well-mixed solution of titanium tetrachloride, silicon tetrachloride, and zirconium tetrachloride. The electrical properties of the sol-gel-derived NC memory are demonstrated in terms of memory window, charge retention, program speed, and endurance. The memory window of the NC memory from the novel hot-hole-trapping mechanism can be achieved up to 4.18 +/- 0.21 V, and long retention times obtained from extrapolation up to 10(6) s are observed as 8%, 13%, and 21% window narrowing under respective temperatures of 25 degrees C, 85 degrees C, and 125 degrees C. The good electrical performance is attributed to the contribution of the high density of isolated NCs and hole-trapped into the deep-trap energy level, so no significant lateral and vertical charge leakage occurs.
Au-Ag core-shell nanoparticles with controllable shell thicknesses for the detection of adenosine by surface enhanced Raman scattering
(2015-05-01)
Ko, Fu-Hsiang
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Tai, Ming-Rou
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Liu, Fu-Ken
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Chang, Yu-Cheng
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材料科學與工程學系
In this study, we report a feasible aqueous chemical method to synthesize Au core-Ag shell nanoparticles (NPs) by seeding growth approach. The concentration of Au NPs plays an important role in growing the different thicknesses of Ag shells. The design of signaling aptamer utilizes the target-induced switching between an aptamer/DNA duplex and an aptamer/target complex. The surface enhanced Raman scattering (SERS) signal was enhanced upon the hybridization of the Raman reporter-labeled DNA released from the target-induced displacement with the captured DNA immobilized on the silicon substrate with Au-Ag core-shell NPs. This substrate with 12.4 nm Ag shell shows high reproducibility, strong enhancement, and a low detection limit (1 nM). The enhancement in DNA-based adenosine detection properties shall be advantageous in applications for other aptamer sensing systems. (C) 2015 Elsevier B.V. All rights reserved.
Controlled Growth Density and Patterning of Silica Nanorings and Nanowires with Enhanced Ultraviolet Cathodoluminescence Peak
(2012-09-01)
Chang, Tung-Hao
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Lai, Yuan-Chun
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Chang, Yu-Cheng
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Ko, Fu-Hsiang
;
Liu, Fu-Ken
This study reports the use of monodisperse Au nanoparticles (NPs) as a catalyst for growing silica nanorings (NRs) and nanowires (NWs). Combining spin coating and optical lithography strategies makes it possible to fabricate pattern-monolayer Au NPs that self-assemble on a 3-aminopropyltrimethoxysilane (APTMS)-modified silicon substrate. This can be used as a catalyst for the selective-area growth of silica NRs and NWs. Cathodoluminescence (CL) analysis reveals these NRs and NWs materials exhibit a blue-light emitting phenomenon. The novel optical properties of these materials are advantageous in applications for light-emitting devices with nanoscale dimensions.
Electroless Plating Growth Au-Ag Core-Shell Nanoparticles for Surface Enhanced Raman Scattering
(2013-05-01)
Chang, Tung-Hao
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Chang, Yu-Cheng
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Ko, Fu-Hsiang
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Liu, Fu-Ken
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材料科學與工程學系
Au core-Ag shell nanoparticles (NPs) have been grown on the silicon substrate with self-assembled well-define Au NPs by electroless plating method. The holding time of spin-coating strategy is a facile method for controlling the densities of Au NPs and treating them as an electrode for selective growth of Ag shell. The volumes of silver nitrate play an important role in growing the different shell thicknesses of Au-Ag core-shell NPs. The appropriate shell thicknesses and the densities of Au-Ag core-shell NPs were optimized to yield the greatest surface-enhanced Raman scattering (SERS) effect in rhodamine B molecule. The combination spin-coating strategy and electroless silver plating provide a facile and low cost fabrication method to prepare the different shell thicknesses and densities of Au-Ag core-shell NPs with high SERS enhancement, which shall be of significant value for practical applications of biosensor systems.
Morphology of Colloid-Derived Nanostructures and Structure-Induced Cytotoxicity under Electric Potential Stress
(2013-07-01)
Chao, Cheng-Han
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Chang, Yu-Cheng
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Hsu, Yi-Chieh
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Liu, Fu-Ken
;
Chang, Feng-Chih
In this study, the morphology of two sizes of nanoparticles under different preparation solvents is evaluated. The vendor marked 5 nm sphere-like nanomaterials are not dispersed in water and toluene solvents, while the vendor marked 1-2 mu m nanoparticles are well-dispersed in the water and environments. The behavior of solvent-induced dispersion or aggregation of TiO2 nanomaterials has less relationship with the solvent polarity, but the dimension of nanomaterials has significant effect on the aggregation or dispersion behaviors. The morphology of nanoparticles from these solvents is, therefore, used to explain the observed cytotoxicity. The cytotoxicity of TiO2 particles with different sizes and concentrations are evaluated by MTT assay using murine embryotic fibroblast (NIH/3T3 cells). Most of the TiO2 materials of interest are not cytotoxicity, except for the minor toxic effect to 5 nm spherical nanomaterials at the concentration ranging from 5x10(-6) to 5x10(-2) mu g/mL. These spherical nanoparticles with 1-2 mu m dimension demonstrate no cytotoxicity for dosages ranging from 5x10(-6) to 50 mu g/mL, irrespective of the dosing time and dispersion behavior. The cytotoxicity of applied electrical potential is strongly dependent on the initial size of nanoparticles. The smallest 5 nm nanomaterials seems more to toxicity with duration of electric potential from 10 V stress. On the contrary, the vendor marked 1-2 mu m nanoparticles owing to largest sizes demonstrates no significant cytotoxicity.
Potential role of gold nanoparticles for improved analytical methods: an introduction to characterizations and applications
(2011-01-01)
Wu, Chung-Shu
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Liu, Fu-Ken
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Ko, Fu-Hsiang
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材料科學與工程學系
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材料科學與工程學系奈米科技碩博班
Nanoparticle-based material is a revolutionary scientific and engineering venture that will invariably impact the existing analytical separation and preconcentration for a variety of analytes. Nanoparticles can be regarded as a hybrid between small molecule and bulk material. A material on the nanoscale produces considerable changes on various properties, making them size- and shape-dependent. Gold nanoparticles (Au NPs), one of the wide variety of core materials available, coupled with tunable surface properties in the form of inorganic or inorganic-organic hybrid have been reported as an excellent platform for a broad range of analytical methods. This review aims to introduce the basic principles, examples, and descriptions of methods for the characterization of Au NPs by using chromatography, electrophoresis, and self-assembly strategies for separation science. Some of the latest important applications of using Au NPs as stationary phases toward open-tubular capillary electrochromatography, gas chromatography, and liquid chromatography as well as roles of run buffer additive to enhance separation and preconcentration in the field of chromatographic, electrophoretic and in chip-based systems are reviewed. Additionally, we review Au NPs-assisted state-of-the-art techniques involving the use of micellar electrokinetic chromatography, an online diode array detector, solid-phase extraction, and mass spectrometry for the preconcentration of some chemical compounds and biomolecules.
Surface Cleaning of the Nanowire Field-Effect Transistor for Gene Detection
(2011-12-01)
Wu, Chi-Chang
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Liu, Fu-Ken
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Lin, Ling-Hung
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Pang, See-Tong
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Chuang, Cheng-Keng
The efficiency of DNA immobilization by using various surface cleaning methods is studied in this work. The degree of surface cleaning is evaluated by the surface tension measurement to reveal the contribution from the polar and apolar terms. The observation from the fluorescent microscope images indicates the effectiveness of surface clean by the acetone and ethanol mixtures, as well as the sulphuric acid and hydrogen peroxide mixtures. We also fabricate a series of back-gated, 60-nm nanowired (NW) field-effect transistor (FET) sensors for mutation gene detection by following the developed acetone and ethanol mixtures. Electrical properties of the NWFET sensor demonstrate the n-channel depletion characteristics. The current of the sensor is reduced once the attachment of negative charge molecules. The single-stranded capture DNA is chemically immobilized onto the surface of silicon NWFET by three-step reactions. The sensor surface demonstrates the great performance of current shift after the suitable cleaning. The NWFET sensor is successfully applied to detect the BRAF(V599E) mutation genes from the hybridized processes. The sensing behaviour estimated from the electrical signal reaches the femtomolar level.