18 results on '"Yang, Shu-Meng"'
Search Results
2. Synthesis and Physical Characteristics of Undoped and Potassium-Doped Cubic Tungsten Trioxide Nanowires through Thermal Evaporation.
- Author
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Sung, Po-Heng, Yen, Hsi-Kai, Yang, Shu-Meng, and Lu, Kuo-Chang
- Subjects
FIELD emission ,NANOWIRES ,TUNGSTEN trioxide ,HIGH resolution electron microscopy ,X-ray photoelectron spectroscopy ,ELECTRIC fields - Abstract
We report an efficient method to synthesize undoped and K-doped rare cubic tungsten trioxide nanowires through the thermal evaporation of WO
3 powder without a catalyst. The WO3 nanowires are reproducible and stable with a low-cost growth process. The thermal evaporation processing was conducted in a three-zone horizontal tube furnace over a temperature range of 550–850 °C, where multiple substrates were placed at different temperature zones. The processing parameters, including pressure, temperature, type of gas, and flow rate, were varied and studied in terms of their influence on the morphology, aspect ratio and density of the nanowires. The morphologies of the products were observed with scanning electron microscopy. High resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction studies were conducted to further identify the chemical composition, crystal structure and growth direction of the nanostructures. Additionally, the growth mechanism has been proposed. Furthermore, we investigated the potassium doping effect on the physical properties of the nanostructures. Photoluminescence measurements show that there were shorter emission bands at 360 nm and 410 nm. Field emission measurements show that the doping effect significantly reduced the turn-on electric field and increased the enhancement factor. Furthermore, as compared with related previous research, the K-doped WO3 nanowires synthesized in this study exhibited excellent field emission properties, including a superior field enhancement factor and turn-on electric field. The study reveals the potential of WO3 nanowires in promising applications for sensors, field emitters and light-emitting diodes. [ABSTRACT FROM AUTHOR]- Published
- 2023
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3. Controlled Synthesis and Enhanced Gas Sensing Performance of Zinc-Doped Indium Oxide Nanowires.
- Author
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Yu, Che-Wen, Fu, Hsuan-Wei, Yang, Shu-Meng, Lin, Yu-Shan, and Lu, Kuo-Chang
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NANOWIRES ,LIFE sciences ,INDIUM oxide ,CHEMICAL vapor deposition ,X-ray photoelectron spectroscopy ,ELECTRIC conductivity ,N-type semiconductors - Abstract
Indium oxide (In
2 O3 ) is a widely used n-type semiconductor for detection of pollutant gases; however, its gas selectivity and sensitivity have been suboptimal in previous studies. In this work, zinc-doped indium oxide nanowires with appropriate morphologies and high crystallinity were synthesized using chemical vapor deposition (CVD). An accurate method for electrical measurement was attained using a single nanowire microdevice, showing that electrical resistivity increased after doping with zinc. This is attributed to the lower valence of the dopant, which acts as an acceptor, leading to the decrease in electrical conductivity. X-ray photoelectron spectroscopy (XPS) analysis confirms the increased oxygen vacancies due to doping a suitable number of atoms, which altered oxygen adsorption on the nanowires and contributed to improved gas sensing performance. The sensing performance was evaluated using reducing gases, including carbon monoxide, acetone, and ethanol. Overall, the response of the doped nanowires was found to be higher than that of undoped nanowires at a low concentration (5 ppm) and low operating temperatures. At 300 °C, the gas sensing response of zinc-doped In2 O3 nanowires was 13 times higher than that of undoped In2 O3 nanowires. The study concludes that higher zinc doping concentration in In2 O3 nanowires improves gas sensing properties by increasing oxygen vacancies after doping and enhancing gas molecule adsorption. With better response to reducing gases, zinc-doped In2 O3 nanowires will be applicable in environmental detection and life science. [ABSTRACT FROM AUTHOR]- Published
- 2023
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4. Catalyst-free synthesis of tungsten oxide nanowires via thermal evaporation for fast-response electrochromic devices.
- Author
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Wang, Chih-Hao, Yen, Hsi-Kai, Yang, Shu-Meng, and Lu, Kuo-Chang
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NANOWIRES ,ELECTROCHROMIC devices ,TUNGSTEN oxides ,SILICON nanowires ,INDIUM tin oxide ,TUNGSTEN alloys ,TRANSMISSION electron microscopy ,TUNGSTEN trioxide - Abstract
Tungsten oxide has drawn widespread attention due to its outstanding physical properties; however, the use of high temperature, low pressure, and expensive catalysts has been challenging in the synthesis of tungsten oxide nanowires. In this study, we developed a single step thermal evaporation process without any catalyst to synthesize WO
3−x nanowires on silicon substrates and indium tin oxide glass substrate safely and economically. We utilized the Taguchi method to design experiments for the synthesis of tungsten oxide nanowires and analyze the effect of processing parameters. The growth mechanism of nanowires is proposed to be a vapor–solid mechanism. Confirmed to be oxygen-vacancy-rich WO3−x nanowires through high-resolution transmission electron microscopy studies, the nanowires have a great morphology with a high aspect ratio of around 700. The electrical resistivity of a single WO3−x nanowire at 300 K was measured to be 2.32 × 10−5 Ω M, which is relatively low due to rich oxygen vacancies. We synthesized WO3−x nanowires on an indium tin oxide glass substrate and assembled electrochromic devices with LiClO4 /PC as the electrolyte. The devices were demonstrated to have fast coloring and bleaching rates of less than one second at low voltage; at high voltage, the color of the devices could change to a deeper color but take more than 2 seconds to react. Compared with previous works, the electrochromic devices from this study exhibit superior response time and stability. These significant results make WO3−x nanowires promising materials for applications in semiconductors, nanodevices, display and green technology. [ABSTRACT FROM AUTHOR]- Published
- 2022
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5. Chemical Vapor Deposition-Fabricated Manganese-Doped and Potassium-Doped Hexagonal Tungsten Trioxide Nanowires with Enhanced Gas Sensing and Photocatalytic Properties.
- Author
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Chen, Pin-Ru, Fu, Hsuan-Wei, Yang, Shu-Meng, and Lu, Kuo-Chang
- Abstract
Owing to its unique and variable lattice structure and stoichiometric ratio, tungsten oxide is suitable for material modification; for example, doping is expected to improve its catalytic properties. However, most of the doping experiments are conducted by hydrothermal or multi-step synthesis, which is not only time-consuming but also prone to solvent contamination, having little room for mass production. Here, without a catalyst, we report the formation of high-crystallinity manganese-doped and potassium-doped tungsten oxide nanowires through chemical vapor deposition (CVD) with interesting characterization, photocatalytic, and gas sensing properties. The structure and composition of the nanowires were characterized by transmission electron microscopy (TEM) and energy-dispersive spectroscopy (EDS), respectively, while the morphology and chemical valence were characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), respectively. Electrical measurements showed that the single nanowires doped with manganese and potassium had resistivities of 1.81 × 0
−5 Ω·m and 1.93 × 10−5 Ω·m, respectively. The doping contributed to the phase transition from monoclinic to metastable hexagonal for the tungsten oxide nanowires, the structure of which is known for its hexagonal electron channels. The hexagonal structure provided efficient charge transfer and enhanced the catalytic efficiency of the tungsten oxide nanowires, resulting in a catalytic efficiency of 98.5% for the manganese-doped tungsten oxide nanowires and 97.73% for the potassium-doped tungsten oxide nanowires after four hours of degradation of methylene blue. Additionally, the gas sensing response for 20 ppm of ethanol showed a positive dependence of doping with the manganese-doped and potassium-doped responses being 14.4% and 29.7%, respectively, higher than the pure response at 250 °C. The manganese-doped and potassium-doped tungsten oxide nanowires are attractive candidates in gas sensing, photocatalytic, and energy storage applications, including water splitting, photochromism, and rechargeable batteries. [ABSTRACT FROM AUTHOR]- Published
- 2022
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6. Fabrication and Photocatalytic Properties of Zinc Tin Oxide Nanowires Decorated with Silver Nanoparticles.
- Author
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Su, Jia-Chi, Hsieh, Tsung-Lin, Yang, Shu-Meng, Chao, Shao-Chun, and Lu, Kuo-Chang
- Abstract
With the continuous advancement of high-tech industries, how to properly handle pollutants has become urgent. Photocatalysis is a solution that may effectively degrade pollutants into harmless molecules. In this study, we synthesized single crystalline Zn
2 SnO4 (ZTO) nanowires through chemical vapor deposition and selective etching. The chemical bath redox method was used to modify the ZTO nanowires with Ag nanoparticles to explore the photocatalytic properties of the nanoheterostructures. The combination of the materials here is rare. Optical measurements by photoluminescence (PL) and UV–Vis show that the PL spectrum of ZTO nanowires was mainly in the visible light region and attributed to oxygen vacancies. The luminescence intensity of the nanowires was significantly reduced after modification, demonstrating that the heterojunction could effectively reduce the electron-hole pair recombination. The reduction increased with the increase in Ag decoration. The conversion from the UV–Vis absorption spectrum to the Tauc Plot shows that the band gap of the nanowire was 4.05 eV. With 10 ppm methylene blue (MB) as the degradation solution, ZTO nanowires exhibit excellent photodegradation efficiency. Reusability and stability in photodegradation of the nanowires were demonstrated. Photocatalytic efficiency increases with the number of Ag nanoparticles. The main reaction mechanism was confirmed by photocatalytic inhibitors. This study enriches our understanding of ZTO-based nanostructures and facilitates their applications in water splitting, sewage treatment and air purification. [ABSTRACT FROM AUTHOR]- Published
- 2022
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7. Synthesis and Characterization of Indium Tin Oxide Nanowires with Surface Modification of Silver Nanoparticles by Electrochemical Method.
- Author
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Yang, Shu-Meng, Yen, Hsi-Kai, and Lu, Kuo-Chang
- Subjects
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INDIUM tin oxide , *SILVER nanoparticles , *OPTICAL materials , *CHEMICAL vapor deposition , *NANOSTRUCTURED materials , *NANOWIRES , *ELECTRONIC equipment - Abstract
In this study, indium tin oxide nanowires (ITO NWs) with high density and crystallinity were synthesized by chemical vapor deposition (CVD) via a vapor–liquid–solid (VLS) route; the NWs were decorated with 1 at% and 3 at% silver nanoparticles on the surface by a unique electrochemical method. The ITO NWs possessed great morphologies with lengths of 5~10 μm and an average diameter of 58.1 nm. Characterization was conducted through transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and X-ray photoelectron spectroscope (XPS) to identify the structure and composition of the ITO NWs. The room temperature photoluminescence (PL) studies show that the ITO NWs were of visible light-emitting properties, and there were a large number of oxygen vacancies on the surface. The successful modification of Ag was confirmed by TEM, XRD and XPS. PL analysis reveals that there was an extra Ag signal at around 1.895 eV, indicating the potential application of Ag-ITO NWs as nanoscale optical materials. Electrical measurements show that more Ag nanoparticles on the surface of ITO NWs contributed to higher resistivity, demonstrating the change in the electron transmission channel of the Ag-ITO NWs. ITO NWs and Ag-ITO NWs are expected to enhance the performance of electronic and optoelectronic devices. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
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8. Synthesis of morphology-improved single-crystalline iron silicide nanowires with enhanced physical characteristics.
- Author
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Huang, Wei-Jie, Yang, Shu-Meng, Liao, Tzu-Ting, and Lu, Kuo-Chang
- Subjects
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SILICIDES , *RAPID thermal processing , *CHEMICAL vapor deposition , *MAGNETIC fields , *FIELD emission , *NANOWIRES , *HETEROGENOUS nucleation - Abstract
Single-crystalline iron silicide nanowires were synthesized via an original approach, pre-deposition method (PDM), with significantly improved morphologies and physical characteristics as compared with those fabricated by conventional chemical vapor deposition. In the pre-deposition method, combining rapid thermal annealing (RTA) and chemical vapor deposition (CVD), iron silicide nanowires grew from the heterogeneous nucleation sites on the surface of the thin film without a catalyst or Al2O3 template. The morphology of the nanowires has been considerably improved in terms of alignment and aspect ratio. HRTEM analysis confirms that the nanowires were β-FeSi2 with a crystal direction of [111]. Physical property measurements indicate that compared with CVD β-FeSi2 nanowires, β-FeSi2 nanowires synthesized by the PDM performed better in both the field emission and magnetic properties. Magnetic property measurements show that the coercive field of PDM nanowires increased from 249 Oe to 900 Oe. Field emission studies reveal that the average β value of the CVD β-FeSi2 nanowires was 1060, while that of the PDM nanowires became 1892. Notably, with a furnace, few researchers can successfully synthesize nanowires of β-FeSi2, which is one of the most fascinating silicides for its important applications. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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9. Endoplasmic reticulum stress mediates the arsenic trioxide-induced apoptosis in human hepatocellular carcinoma cells.
- Author
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Zhang, Xin-Yu, Yang, Shu-Meng, Zhang, Hao-Peng, Yang, Yue, Sun, Shi-Bo, Chang, Jian-Ping, Tao, Xuan-Chen, Yang, Tuo-Yun, Liu, Chun, and Yang, Yan-Mei
- Subjects
- *
ENDOPLASMIC reticulum , *PHYSIOLOGICAL stress , *ARSENIC trioxide , *APOPTOSIS , *LIVER cancer , *CANCER cells - Abstract
Arsenic trioxide has been proven to trigger apoptosis in human hepatocellular carcinoma cells. Endoplasmic reticulum stress has been known to be involved in apoptosis through the induction of CCAAT/enhancer-binding protein homologous protein. However, it is unknown whether endoplasmic reticulum stress mediates arsenic trioxide-induced apoptosis in human hepatocellular carcinoma cells. Our data showed that arsenic trioxide significantly induced apoptosis in human hepatocellular carcinoma cells. Furthermore, arsenic trioxide triggered endoplasmic reticulum stress, as indicated by endoplasmic reticulum dilation, upregulation of glucose-regulated protein 78 and CCAAT/enhancer-binding protein homologous protein. We further found that 4-phenylbutyric acid, an inhibitor of endoplasmic reticulum stress, alleviated arsenic trioxide-induced expression of CCAAT/enhancer-binding protein homologous protein. More important, knockdown of CCAAT/enhancer-binding protein homologous protein by siRNA or inhibition of endoplasmic reticulum stress by 4-phenylbutyric acid alleviated apoptosis induced by arsenic trioxide. Consequently, our results suggested that arsenic trioxide could induce endoplasmic reticulum stress-mediated apoptosis in hepatocellular carcinoma cells, and that CCAAT/enhancer-binding protein homologous protein might play an important role in this process. [ABSTRACT FROM AUTHOR]
- Published
- 2015
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10. Set-Triggered-Parallel-Reset Memristor Logic for High-Density Heterogeneous-Integration Friendly Normally Off Applications.
- Author
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Chang, Meng-Fan, Yang, Shu-Meng, Kuo, Chia-Chen, Yang, Ting-Chin, Yeh, Che-Ju, Chien, Tun-Fei, Huang, Li-Yue, Sheu, Shyh-Shyuan, Tseng, Pei-Ling, Chen, Yu-Sheng, Chen, Frederick T., Ku, Tzu-Kun, Tsai, Ming-Jinn, and Kao, Ming-Jer
- Abstract
Memristor devices are promising as high-density computing logic for non-high-speed normally off applications using heterogeneous technologies. This brief proposes a set-triggered-parallel-reset memristor logic (STPR-ML)-based on back-end-of-line-based bipolar-type memristor devices to reduce the area overhead and increase compatibility with standard and nonstandard CMOS processes. The proposed STPR-ML has two subsets: with and without nonvolatile storage capability. Two types of physical structures are also proposed for STPR-ML: 2-D and 3-D. A test chip using 2-D \HfOx memristor devices was fabricated using a CMOS process to confirm the functionality of the
nand ,nor , andxor gates used in STPR-ML. The proposed STPR-ML achieves a $2\sim 8\times$ reduction in area compared with CMOS logic gates with four or more inputs. [ABSTRACT FROM PUBLISHER]- Published
- 2015
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11. A Sub-0.3 V Area-Efficient L-Shaped 7T SRAM With Read Bitline Swing Expansion Schemes Based on Boosted Read-Bitline, Asymmetric-VTH Read-Port, and Offset Cell VDD Biasing Techniques.
- Author
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Chang, Meng-Fan, Chen, Ming-Pin, Chen, Lai-Fu, Yang, Shu-Meng, Kuo, Yao-Jen, Wu, Jui-Jen, Su, Hsiu-Yun, Chu, Yuan-Hua, Wu, Wen-Ching, Yang, Tzu-Yi, and Yamauchi, Hiroyuki
- Subjects
STATIC random access memory chips ,INTEGRATED memory circuits ,LOW voltage integrated circuits ,TRANSISTORS ,OFFSET reflector antennas ,AMPLITUDE variation with offset analysis - Abstract
In previous SRAM designs, reducing minimum operating voltage (VDDmin) inevitably resulted in devices with a large cell area (A). This work proposes an L-shaped 7T cell (L7T) and read-bitline (RBL) swing expansion scheme (RBL-EXPD) to minimize A\astVDDmin for low-voltage applications. This L7T features an area-efficient cell layout and a read-disturb free decoupled 1T read port (RP) capable of providing a wide space for write margin improvement. The RBL-EXPD employs (1) boosted RBL (BRBL), (2) 1T-RP with asymmetric-VTH, (AV-1TRP) and (3) offset cell-VDD biasing (OFS-CVDD) to expand RBL swing in both the upward and downward directions securing both ‘High’ and ‘Low’ sensing margins. A 65 nm 256-row 32 Kb L7T SRAM macro-fabricated using BRBL and AVTH-RP achieved a 260 mV VDDmin. The resulting A\astVDDmin is ~50% lower than that of conventional 8T SRAM devices. [ABSTRACT FROM AUTHOR]
- Published
- 2013
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12. Low-Voltage Embedded NAND-ROM Macros Using Data-Aware Sensing Reference Scheme for VDDmin, Speed and Power Improvement.
- Author
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Yang, Shu-Meng, Chang, Meng-Fan, Chiang, Chi-Chuang, Chen, Ming-Pin, and Yamauchi, Hiroyuki
- Subjects
LOW voltage integrated circuits ,READ-only memory ,TRANSISTORS ,ELECTRONIC amplifiers ,ELECTRONIC noise ,ENERGY consumption - Abstract
Density-prioritized memories such as NAND-ROM require a longer single-ended bitline (BL) sensing scheme to maintain high cell array efficiency and therefore suffer from a reduced BL sensing margin at ultra-low supply voltages (VDD) for read-0. This is the result of 1) reduced BL discharge driving current due to limited cell size and driving voltage; and 2) a larger BL false drop noise for read-1. This study proposes a data-aware sensing reference (DASR) scheme, capable of maintaining sensing margins for both read-0 and read-1 under given timing constraints. The key mechanism involved in maintaining the sensing margin is the adaptive changing of the reference voltage (VREF), such that the sensing headroom or potential range (VBL-VREF) for read-1 and read-0 overlap, as in differential BL sensing. Two 256 Kb DASR NAND-ROM macros, with and without code-inversion schemes, were fabricated using a 90 nm bulk CMOS logic process. The 256 Kb DASR NAND-ROM macros are functional down to 0.25 V. DASR also increases the access speed by 66.7% at 0.31 V VDD, compared with the conventional approach without the proposed DASR scheme. [ABSTRACT FROM AUTHOR]
- Published
- 2013
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13. Noise-Immune Embedded NAND-ROM Using a Dynamic Split Source-Line Scheme for VDDmin and Speed Improvements.
- Author
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Chang, Meng-Fan, Yang, Shu-Meng, Liang, Chih-Wei, Chiang, Chih-Chyuang, Chiu, Pi-Feng, and Lin, Ku-Feng
- Abstract
Embedded NAND-type read-only-memory (NAND-ROM) provides large-capacity, high-reliability, on-chip non-volatile storage. However, NAND-ROM suffers from code-dependent read noises and cannot survive at low supply voltages (VDDs). These code-dependent read noises are primarily due to the charge-sharing effect, bitline leakage current, and crosstalk between bitlines, which become worse at lower VDD. This study proposes a dynamic split source-line (DSSL) scheme for NAND-ROM. The proposed scheme overcomes code-dependent read noises while improving the read access time and suppressing the active-mode gate leakage current, with only a 1% area penalty in the cell array. Experiments on a fabricated 256 Kb macro using a 90 nm industrial logic process demonstrate that the proposed DSSL scheme achieves 100% code-pattern coverage under a small sensing margin. Additionally, the DSSL NAND-ROM works with a wide range of supply voltages (1–0.31 V) with a 38%, 45.8%, and 37% improvement in speed, power, and standby current, respectively, at VDD~=~1 V. [ABSTRACT FROM PUBLISHER]
- Published
- 2010
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14. A 0.5V 4Mb logic-process compatible embedded resistive RAM (ReRAM) in 65nm CMOS using low-voltage current-mode sensing scheme with 45ns random read time.
- Author
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Chang, Meng-Fan, Wu, Che-Wei, Kuo, Chia-Cheng, Shen, Shin-Jang, Lin, Ku-Feng, Yang, Shu-Meng, King, Ya-Chin, Lin, Chorng-Jung, and Chih, Yu-Der
- Abstract
Numerous low-supply-voltage (VDD) mobile chips, such as energy-harvesting-powered devices and biomedical applications, require low-VDD on-chip nonvolatile memory (NVM) for low-power active-mode access and power-off data storage. However, conventional NVMs cannot achieve low-VDD operation due to insufficient write voltage generated by charge-pumped (CP) circuits at a low VDD, and a lack of low-VDD current-mode sense amplifiers (CSA) [1–4] to overcome read issues in reduced sensing margins, degraded speeds, and insufficient voltage headroom (VHR). Resistive RAM (ReRAM) [4–6] is a promising memory with the advantages of short write time, low write-voltage, and reduced write power compared to Flash and other NVMs. Using a low-VDD CP with relaxed output voltage/current requirements for write operations, ReRAM is a good candidate for on-chip low-VDD NVM if a low-VDD CSA is provided, particularly for frequent-read-seldom-write applications. We develop a body-drain-driven CSA (BDD-CSA) with dynamic BL bias voltage (VBL) and small VHR for larger sensing margins to achieve a lower VDDmin, faster read speed, and better tolerance of read cell current (ICELL) and BL leakage current (IBL-LEAK) variations compared to conventional CSAs. A fabricated 65nm 4Mb ReRAM macro using the BDD-CSA and our CMOS-logic-compatible ReRAM cell [7] achieves 0.5V VDDmin. The BDD-CSA achieves 0.32V VDDmin. [ABSTRACT FROM PUBLISHER]
- Published
- 2012
- Full Text
- View/download PDF
15. Synthesis of High-Density Indium Oxide Nanowires with Low Electrical Resistivity.
- Author
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Chen, Yu-Yang, Yang, Shu-Meng, and Lu, Kuo-Chang
- Subjects
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NANOWIRES , *ELECTRICAL resistivity , *INDIUM oxide , *CHEMICAL vapor deposition , *CRYSTAL defects , *TRANSMISSION electron microscopy , *CARRIER gas - Abstract
In this study, indium oxide nanowires of high-density were synthesized by chemical vapor deposition (CVD) through a vapor–liquid–solid (VLS) mechanism without carrier gas. The indium oxide nanowires possess great morphology with an aspect ratio of over 400 and an average diameter of 50 nm; the length of the nanowires could be over 30 μm, confirmed by field-emission scanning electron microscopy (SEM). Characterization was conducted with X-ray diffraction (XRD), transmission electron microscopy (TEM), photoluminescence spectrum (PL). High-resolution TEM studies confirm that the grown nanowires were single crystalline c-In2O3 nanowires of body-centered cubic structures. The room temperature PL spectrum shows a strong peak around 2.22 eV, originating from the defects in the crystal structure. The electrical resistivity of a single indium oxide nanowire was measured to be 1.0 × 10−4 Ω⋅cm, relatively low as compared with previous works, which may result from the abundant oxygen vacancies in the nanowires, acting as unintentional doping. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
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16. Single Crystalline Higher Manganese Silicide Nanowire Arrays with Outstanding Physical Properties through Double Tube Chemical Vapor Deposition.
- Author
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Shen, Chin-Li, Yang, Shu-Meng, and Lu, Kuo-Chang
- Subjects
- *
SILICON nanowires , *CHEMICAL vapor deposition , *NANOWIRES , *CURIE temperature , *MANGANESE , *FIELD emission - Abstract
In this work, we report a novel and efficient silicidation method to synthesize higher manganese silicide (HMS) nanowires with interesting characterization and physical properties. High density silicon nanowire arrays fabricated by chemical etching reacted with MnCl2 precursor through a unique double tube chemical vapor deposition (CVD) system, where we could enhance the vapor pressure of the precursor and provide stable Mn vapor with a sealing effect. It is crucial that the method enables the efficient formation of high quality higher manganese silicide nanowires without a change in morphology and aspect ratio during the process. X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were utilized to characterize the HMS nanowires. High-resolution TEM studies confirm that the HMS nanowires were single crystalline Mn27Si47 nanowires of Nowotny Chimney Ladder crystal structures. Magnetic property measurements show that the Mn27Si47 nanowire arrays were ferromagnetic at room temperature with a Curie temperature of over 300 K, highly depending on the relationship between the direction of the applied electric field and the axial direction of the standing nanowire arrays. Field emission measurements indicate that the 20 μm long nanowires possessed a field enhancement factor of 3307. The excellent physical properties of the HMS nanowires (NWs) make them attractive choices for applications in spintronic devices and field emitters. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
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17. Synthesis and Photocatalytic Properties of CuO-CuS Core-Shell Nanowires.
- Author
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Kao, Yuan-Tse, Yang, Shu-Meng, and Lu, Kuo-Chang
- Subjects
- *
PHOTOCATALYSIS , *COPPER oxide , *COPPER sulfide , *STRUCTURAL shells , *SYNTHESIS of nanowires , *THERMAL oxidation (Materials science) - Abstract
In this study, an efficient method to synthesize CuO-CuS core-shell nanowires by two-step annealing process was reported. CuO nanowires were prepared on copper foil via thermal oxidation in a three-zone horizontal tube furnace. To obtain larger surface area for photocatalytic applications, we varied four processing parameters, finding that growth at 550 °C for 3 h with 16 °C/min of the ramping rate under air condition led to CuO nanowires of appropriate aspect ratio and number density. The second step, sulfurization process, was conducted to synthesize CuO-CuS core-shell nanowires by annealing with sulfur powder at 250 °C for 30 min under lower pressure. High-resolution transmission electron microscopy studies show that a 10 nm thick CuS shell formed and the growth mechanism of the nanowire heterostructure has been proposed. With BET, the surface area was measured to be 135.24 m2·g−1. The photocatalytic properties were evaluated by the degradation of methylene blue (MB) under visible light irradiation. As we compared CuO-CuS core-shell nanowires with CuO nanowires, the 4-hour degradation rate was enhanced from 67% to 89%. This could be attributed to more effective separation of photoinduced electron and hole pairs in the CuO-CuS heterostructure. The results demonstrated CuO-CuS core-shell nanowires as a promising photocatalyst for dye degradation in polluted water. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
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18. A 260mV L-shaped 7T SRAM with bit-line (BL) Swing expansion schemes based on boosted BL, asymmetric-VTH read-port, and offset cell VDD biasing techniques.
- Author
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Chen, Ming-Pin, Chen, Lai-Fu, Chang, Meng-Fan, Yang, Shu-Meng, Kuo, Yao-Jen, Wu, Jui-Jen, Ho, Mon-Shu, Su, Hsiu-Yun, Chu, Yuan-Hua, Wu, Wen-Ching, Yang, Tzu-Yi, and Yamauchi, Hiroyuki
- Abstract
This work proposes bit-line (BL) swing expansion schemes (BL-EXPD), which minimize the product (A*VDDmin) of SRAM cell area (A) and the minimum operation voltage (VDDmin) to the best of our knowledge. The key-enablers to minimize A*VDDmin are: L-shaped 7T cell (L7T) and BL-EXPD. The L7T features: (1) an area efficient cell layout, (2) a read-disturb free decoupled 1T read port (RP), and (3) a half-select disturb free write back scheme[1]. The BL-EXPD enables a 9× larger read-BL (RBL) swing at the 6σ point than that in our previously proposed Z8T[2] and allows single BL sensing to reduce cell area. A fabricated 65nm 256-row BL 32Kb L7T SRAM achieved a 260mV VDDmin. As a result, its A*VDDmin is ∼50% lower than for Z8T and conventional 8T SRAM cells [3,4]. [ABSTRACT FROM PUBLISHER]
- Published
- 2012
- Full Text
- View/download PDF
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