Browsing by Author "Ting, Yi-Hsin"

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Applications of p-n homojunction ZnO nanowires to one-diode one-memristor RRAM arrays
(2020-10-01)
Chen, Jui-Yuan
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Wu, Min-Ci
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Ting, Yi-Hsin
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Lee, Wei-Che
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Yeh, Ping-Hung
Nanowire (NW) structure is superior at defining the direction of device due to its one-dimension feature. In this work, the p-n ZnO NWs were successfully synthesized, and were able to vertically grow on Ta2O5 substrate. Thus, the well-performed Au/p-n ZnO NWs/Ta2O5/Au one-diode one-memoristor device was fabricated. The p-n ZnO NWs not only exhibited excellent rectifying behavior, but also played the role of oxygen storing during filaments formation. Therefore, the low-leakage device aimed to build high-density crossbar arrays which was required for accelerating the combination of 5 G with AI in near future applications. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
Atomic Imaging of Molybdenum Oxide Nanowires with Unique and Complex Periodicity by Advanced Electron Microscopy
(2020-03-11)
Ting, Yi-Hsin
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Huang, Chun-Wei
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Yasuhara, Akira
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Chen, Sheng-Yuan
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Chen, Jui-Yuan
Crystalline Mo5O14 exhibits distinctive structural features such as tunnel structure and pseudolamellar arrangement according to the ideal model. However, the spatial resolution of the conventional technique of transmission electron microscopy (TEM) is insufficient to distinguish the actual positions of atoms. In this work, we aimed to systematically analyze and identify the Mo5O14 nanowires fabricated by the chemical vapor deposition (CVD) process. Utilizing high-angle annular dark-field (HAADF), annular bright-field (ABF), and enhanced annular bright-field (E-ABF) within the scanning transmission electron microscope (STEM) mode reveals the structural features at the atomic scale. In addition, the ultrahigh resolution images have confirmed the crystallographic insights in [001] growth direction for the Mo5O14 nanowires with a tunnel structure throughout the nanowire. The cross-sectional images show the unique close-packed plane and atomic arrangement with a network of MoO6 octahedra and MoO7 pentagonal bipyramids. These results are consistent with the theoretical atomic arrangement, supporting the realization of Mo5O14-type catalysts used in the selective oxidation process and battery applications.
Bioinspired Engineering of a Bacterium-Like Metal-Organic Framework for Cancer Immunotherapy
(1970-01-01)
Chen, Po-Ming
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Pan, Wen-Yu
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Miao, Yang-Bao
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Liu, Yu-Miao
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Luo, Po-Kai
Bacteria-mediated tumor therapy (BMTT) has been known for decades; however, its clinical use is inhibited by its association with infections. To address this issue, a spiky, bacterium-like metal-organic framework (MOF), which can replicate the functional responses of BMTT without its adverse side-effects, is proposed. MOFs are synthesized in a solvothermal reaction of aluminum sulfate, ruthenium chloride hydrate, and 2-aminoterephthalic acid; they have a spherical morphology or many nanospikes on their surfaces, depending on the reaction temperature. Both spherical and spiky MOFs can function as photothermal agents, converting absorbed optical energy into local heat. Owing to their higher surface area of interaction, spiky MOFs are more easily phagocytosed by macrophages than are spherical MOFs, strengthening their immune responses. Moreover, when injected intratumorally, spiky MOFs reside significantly longer than spherical ones, enabling their use in repeated photothermal treatments. The combination of in situ vaccination with intratumorally injected bacterium-like MOFs under exposure to an near-infrared laser and the immune checkpoint blockade of systemically administered alpha PD-1 is evaluated in tumor-bearing mice. The results indicate that the checkpoint blockade acts synergistically with in situ vaccination to provide diverse antitumor functions of BMTT, destroying a primary tumor and suppressing tumor recurrence and metastasis.
Dynamic Observation of Phase Transformation Behaviors in Indium(III) Selenide Nanowire Based Phase Change Memory
(2014-09-01)
Huang, Yu-Ling
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Huang, Chun-Wei
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Chen, Jui-Yuan
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Ting, Yi-Hsin
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Lu, Kuo-Chang
Phase change random access memory (PCRAM) has been extensively investigated for its potential applications in next-generation nonvolatile memory. In this study, indium(III) selenide (In2Se3) was selected due to its high resistivity ratio and lower programming current. Au/In2Se3-nanowire/Au phase change memory devices were fabricated and measured systematically in an in situ transmission electron microscope to perform a RESET/SET process under pulsed and dc voltage swept mode, respectively. During the switching, we observed the dynamic evolution of the phase transformation process. The switching behavior resulted from crystalline/amorphous change and revealed that a long pulse width would induce the amorphous or polycrystalline state by different pulse amplitudes, supporting the improvement of the writing speed, retention, and endurance of PCRAM.
Low Power Consumption Nanofilamentary ECM and VCM Cells in a Single Sidewall of High-Density VRRAM Arrays
(1970-01-01)
Wu, Min-Ci
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Ting, Yi-Hsin
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Chen, Jui-Yuan
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Wu, Wen-Wei
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交大名義發表
The technologies of 3D vertical architecture have made a major breakthrough in establishing high-density memory structures. Combined with an array structure, a 3D high-density vertical resistive random access memory (VRRAM) cross-point array is demonstrated to efficiently increase the device density. Though electrochemical migration (ECM) resistive random access (RRAM) has the advantage of low power consumption, the stability of the operating voltage requires further improvements due to filament expansions and deterioration. In this work, 3D-VRRAM arrays are designed. Two-layered RRAM cells, with one inert and one active sidewall electrode stacked at a cross-point, are constructed, where the thin film sidewall electrode in the VRRAM structure is beneficial for confining the expansions of the conducting filaments. Thus, the top cell (Pt/ZnO/Pt) and the bottom cell (Ag/ZnO/Pt) in the VRRAM structure, which are switched by different mechanisms, can be analyzed at the same time. The oxygen vacancy filaments in the Pt/ZnO/Pt cell and Ag filaments in the Ag/ZnO/Pt cell are verified. The 40 nm thickness sidewall electrode restricts the filament size to nanoscale, which demonstrates the stability of the operating voltages. Additionally, the 0.3 V operating voltage of Ag/ZnO/Pt ECM VRRAM demonstrates the potential of low power consumption of VRRAM arrays in future applications.
Mass transport phenomena in copper nanowires at high current density
(2016-04)
Huang, Yu-Ting
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Huang, Chun-Wei
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Chen, Jui-Yuan
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Ting, Yi-Hsin
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Cheng, Shao-Liang
Electromigration in Cu has been extensively investigated as the root cause of typical breakdown failure in Cu interconnects. In this study, Cu nanowires connected to Au electrodes are fabricated and observed using in situ transmission electron microscopy to investigate the electro- and thermo-migration processes that are induced by direct current sweeps. We observe the dynamic evolution of different mass transport mechanisms. A current density on the order of 10(6) A/cm(2) and a temperature of approximately 400 A degrees C are sufficient to induce electro- and thermo-migration, respectively. Observations of the migration processes activated by increasing temperatures indicate that the migration direction of Cu atoms is dependent on the net force from the electric field and electron wind. This work is expected to support future design efforts to improve the robustness of Cu interconnects.
Ni/NiO/HfO2 Core/Multishell Nanowire ReRAM Devices with Excellent Resistive Switching Properties
(2018-11-01)
Huang, Ting-Kai
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Chen, Jui-Yuan
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Ting, Yi-Hsin
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Wu, Wen-Wei
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交大名義發表
Resistive random-access memory (ReRAM) is one of the most promising types of nonvolatile memory because it has several important advantages, for example, a simple metal-insulator-metal structure, fast operating speed, high endurance, high retention, and low energy consumption. However, the reliability of ReRAM nanodevices is not persistent, and the complete switching mechanism is not fully understood. In this study, a unique 1D Ni/NiO/HfO2 core/multishell ReRAM nanodevice is designed and fabricated. The different properties, including the electrical characteristics, surface morphology, and elemental distribution, are systematically investigated. The Ni/NiO/HfO2 heterostructure nanowire ReRAM device exhibits excellent electrical characteristics and resistive switching properties. It is remarkable that the endurance could be maintained up to 200 cycles, which is extremely good for a 1D ReRAM device. Additionally, a focused-ion beam technique is used to prepare samples for subsequent transmission electron microscopic (TEM) observation. From the TEM analysis, the position of the conducting filaments is verified and the elemental composition of the conducting filaments is confirmed. The migration of hafnium ions forms the conducting filaments between the HfO2 layer and Ni core, resulting in the switching characteristic. The study enriches the understanding of the mechanism and provides a design to enhance the resistive switching properties of ReRAM nanodevices.
Observation of Resistive Switching Behavior in Crossbar Core-Shell Ni/NiO Nanowires Memristor
(2018-02-08)
Ting, Yi-Hsin
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Chen, Jui-Yuan
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Huang, Chun-Wei
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Huang, Ting-Kai
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Hsieh, Cheng-Yu
The crossbar structure of resistive random access memory (RRAM) is the most promising technology for the development of ultrahigh-density devices for future nonvolatile memory. However, only a few studies have focused on the switching phenomenon of crossbar RRAM in detail. The main purpose of this study is to understand the formation and disruption of the conductive filament occurring at the crossbar center by real-time transmission electron microscope observation. Core-shell Ni/NiO nanowires are utilized to form a cross-structure, which restrict the position of the conductive filament to the crosscenter. A significant morphological change can be observed near the crossbar center, which results from the out-diffusion and backfill of oxygen ions. Energy dispersive spectroscopy and electron energy loss spectroscopy demonstrate that the movement of the oxygen ions leads to the evolution of the conductive filament, followed by redox reactions. Moreover, the distinct reliability of the crossbar device is measured via ex situ experiments. In this work, the switching mechanism of the crossbar core-shell nanowire structure is beneficial to overcome the problem of nanoscale minimization. The experimental method shows high potential to fabricate high-density RRAM devices, which can be applied to 3D stacked package technology and neuromorphic computing systems.
Observing Solid-State Formation of Oriented Porous Functional Oxide Nanowire Heterostructures by in Situ TEM
(2018-09-01)
Ho, Jo-Hsuan
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Ting, Yi-Hsin
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Chen, Jui-Yuan
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Huang, Chun-Wei
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Tsai, Tsung-Chun
Transition metal oxide nanowires have attracted extensive attention because of their physical characteristics. Among them, ZnO nanowires have great potential. Due to the multifunctional properties of ZnO, devices built using ZnO-based heterostructures always perform well. In this study, interesting diffusion behavior between ZnO nanowires and Fe metal was observed by using in situ transmission electron microscopy. ZnO nanowires and Fe metal were annealed under ultrahigh vacuum (UHV) conditions at 800 K. By controlling the annealing time for the solid-state diffusion, porous Fe3O4 and unique ZnO/porous Fe3O4 nanowire heterostructures were formed. As-formed porous Fe3O4 nanowires with voids can be divided into two types by appearance: plate-like voids and zigzag-like hollow voids. From high-resolution transmission electron microscopy (HRTEM) images and fast Fourier transform (FFT) diffraction patterns, we found that plate-like voids formed along the {111} plane, which was the close-packed plane of Fe3O4, and that zigzag-like hollow voids formed along the {111}/{022} planes. Moreover, a transition region existed during diffusion, with a parallel relationship found between the Fe3O4 crystal with plate-like voids and the ZnO crystal. A sharp interface was determined to exist between the Fe3O4 crystal with zigzag-like hollow voids and ZnO. These oriented porous Fe3O4/ZnO axial nanowire heterostructures exhibited a unique appearance and interesting formation behavior. Furthermore, the structures had a high surface-area-to-volume ratio, which is promising for sensing applications.
Ultra-high annealing twin density in < 211 >-oriented Cu films
(2020-07-15)
Chen, Kuan-Ju
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Chen, Jui-Yuan
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Ting, Yi-Hsin
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Wu, Wen-Wei
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Chen, Chih
We reported the fabrication of densely twinned Cu films with highly (211) texture developed from the annealing of <111>-oriented nanotwinned copper (nt-Cu) films. During the annealing at 300 degrees C, abnormal grain growth occurred in the nt-Cu film and resulted in a microstructure dominated by the anomalously large <211>-oriented grains. Moreover, densely-intersected annealing twin bands with <221>, <611>, and <931> orientations are embedded in the large <211> grains. The measured annealing twin density is 0.2 mu m(-1), which is highest among the reported values in previous literatures with similar grain size. Extensive multiple twinning process may occur during the annealing to form the unique microstructure. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
Unique amorphization-mediated growth to form heterostructured silicide nanowires by solid-state reactions
(2019-05-05)
Lin, Wan-Jhen
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Lin, Ting-Yi
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Huang, Chun-Wei
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Ting, Yi-Hsin
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Tsai, Tsung-Chun
Transition metal silicide nanowires exhibit low resistivity, great thermal stability and excellent mechanical strength, contributing to their applications as interconnection and contact materials for future integrated circuits devices. In this work, we successfully fabricated two kinds of chromium silicide/silicon heterostructure nanowires through solid state reactions - bare Si/Cr3Si nanowires and Si/Cr5Si3-Al2O3 core-shell nanowires. The growth behaviors and diffusion mechanisms of the two silicide heterostructure nanowires were investigated with in-situ TEM at 700 degrees C. During the growth of chromium silicide nanowires, unique amorphous Si phase would form first in front of silicide nanowires. Also, we found that oxide-shell could control the diffusion process in silicon nanowires. With oxide-shell, compression stress would restrain the growth of chromium silicide in the radial direction but accelerate its growth rate in the axial direction. Additionally, Al2O3 shell reduced the radial expansion of chromium silicide nanowires and hindered Cr-rich phases with Cr5Si3 appearing as the first phase. The crystal structures of the nanowires have been identified to be single-crystalline A15 and D8m type structure of the intrinsic Cr3Si nanowires and Cr5Si3 nanowires, respectively. In addition to fundamental science, the significant study is beneficial for future processing techniques in nanotechnology and related applications. (C) 2019 Elsevier Ltd.