Browsing by Author "Hung, Chung-Jung"

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Compact Ga-Doped ZnO Nanorod Thin Film for Making High-Performance Transparent Resistive Switching Memory
(2014-10-01)
Huang, Chun-Yang
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Ho, Yen-Ting
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Hung, Chung-Jung
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Tseng, Tseung-Yuen
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材料科學與工程學系
Fully transparent and stable resistive switching characteristics in resistive random access memory (RRAM) device consisting of ITO/Ga doped ZnO (GZO)/ZnO/ITO architecture are proposed. The GZO nanorods with well aligned and extremely dense properties are considered as a thin film for RRAM device. The oxygen vacancies can be confined and migrate along grain boundaries in the GZO nanorod film. Therefore, the weakest point for formation and rupture of conductive filament can be limited at the interface between GZO nanorod film and ZnO seeding layer. Compared with ITO/ZnO/ITO device, a significant improvement in the distribution of high resistance state (HRS) and low resistance state (LRS) during resistance switching is demonstrated in the present device. In addition, a high endurance of more than 7000 cycles with the resistance ratios of HRS/LRS about 200 times is achieved in this device. The ITO/GZO/ZnO/ITO device is a good candidate for the transparent RRAM application.
Electrochromic Properties of Tunsgten Trioxide Nanostructures
(2013)
Huang, Yi-Hsuan
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Hung, Chung-Jung
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Tseng, Tseung-Yuen
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
WO3 is the most widely studied electrochromic material because of its high colouration efficiency and high cyclic stability. Use of tungsten hexachloride as precursor synthesizes the highly porous WO3 nanowire networks by hydrothermal method. Color efficiency of 120.3 cm(2) C-1 during the coloration/bleaching process, high transmittance contrast(57%), and short switching time(t(b)=7 s, t(c)=21 s) can be achieved when employing WO3 nanowire networks as electrochromic devices.
Forming-free bipolar resistive switching in nonstoichiometric ceria films
(2014-01-27)
Ismail, Muhammad
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Huang, Chun-Yang
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Panda, Debashis
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Hung, Chung-Jung
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Tsai, Tsung-Ling
The mechanism of forming-free bipolar resistive switching in a Zr/CeO (x) /Pt device was investigated. High-resolution transmission electron microscopy and energy-dispersive spectroscopy analysis indicated the formation of a ZrO (y) layer at the Zr/CeO (x) interface. X-ray diffraction studies of CeO (x) films revealed that they consist of nano-polycrystals embedded in a disordered lattice. The observed resistive switching was suggested to be linked with the formation and rupture of conductive filaments constituted by oxygen vacancies in the CeO (x) film and in the nonstoichiometric ZrO (y) interfacial layer. X-ray photoelectron spectroscopy study confirmed the presence of oxygen vacancies in both of the said regions. In the low-resistance ON state, the electrical conduction was found to be of ohmic nature, while the high-resistance OFF state was governed by trap-controlled space charge-limited mechanism. The stable resistive switching behavior and long retention times with an acceptable resistance ratio enable the device for its application in future nonvolatile resistive random access memory (RRAM).
Resistive switching characteristics of Pt/CeOx/TiN memory device
(2014-06-01)
Ismail, Muhammad
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Talib, Ijaz
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Huang, Chun-Yang
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Hung, Chung-Jung
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Tsai, Tsung-Ling
The resistive switching characteristics of Pt/CeOx/TiN memory devices are investigated for potential applications in nonvolatile resistive random access memory (RRAM). The X-ray diffraction characteristics of the sputtered CeOx layer indicate the formation of nanocrystalline single-phase CeO2 with a cubic fluorite structure. The existence of oxygen vacancies in the Pt/CeOx/TiN memory device was determined by X-ray photoelectron spectroscopic studies, while the presence of an interfacial layer between CeOx and the TiN bottom electrode was investigated by Xray diffraction and high resolution transmission electron microscopy. The TiON layer formed at the TiN/CeOx interface seems to play a key role in the resistive switching mechanism of the device. The present CeOx-based device shows excellent bipolar resistive switching characteristics, including a low operation current (100 mu A), high ON/OFF resistance ratio (similar to 10(5)), and good retention/stress characteristics at both room temperature and 85 degrees C. (C) 2014 The Japan Society of Applied Physics
Unipolar Resistive Switching in ZrO2 Thin Films
(2013-04-01)
Zhang, Guo-Yong
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Lee, Dai-Ying
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Yao, I-Chuan
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Hung, Chung-Jung
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Wang, Sheng-Yu
Unipolar resistive switching behaviors including bistable memory switching and monostable threshold switching were found in ZrO2 thin films fabricated by a simple sol-gel method with the Ti/ZrO2/Pt structure. The multilevel resistive switching behaviors were also revealed by varying the compliance current from 9 to 38 mA. Physical mechanisms based on a conductive filament model were proposed to explain the resistive switching phenomena and the device breakdown. A figure of merit Z = rho(a)/rho(f) was defined as a criterion for evaluating OFF/ON resistance ratio, where rho(f) and rho(a) represent the resistivities of the conductive filament and the fracture region of the filament, respectively. The advantages such as unipolar resistive switching, multilevel resistive switching, good scalability, low operation voltage (<5 V), high OFF/ON resistance ratio (>10(3)), nondestructive readout, long retention (>10(4) s), and simple fabrication method make the ZrO2-based resistive switching device a promising candidate for next-generation nonvolatile memory applications. (C) 2013 The Japan Society of Applied Physics