Browsing by Author "Wu, Chen-Yu"

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Bistable resistive switching in Al2O3 memory thin films
(2007)
Lin, Chih-Yang
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Wu, Chen-Yu
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Wu, Chung-Yi
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Hu, Chenming
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Tsenga, Tseung-Yuen
In this study, we investigate the resistive switching behavior of radio frequency (rf)-sputtered Al2O3 thin films. It is observed that both high-conducting state (ON state) and low-conducting state (OFF state) are stable and reproducible during successive resistive switchings by dc voltage sweeping. The ratio of resistance of the ON and OFF state is over 10(3). Such a reproducible resistive switching can be performed at 150 degrees C, and the resistance of the ON state can be altered by various current compliances. The conduction mechanisms of the ON and OFF states are demonstrated as ohmic conduction and Frenkel-Poole emission, respectively. Both states, performed by dc voltage sweeping and applying short pulse, are stable over 10(4) s at a read voltage of 0.3 V and the electrical-pulse-induced resistance change (EPIR) phenomenon is demonstrated, which are all important properties for further resistive random access memory application. (c) 2007 The Electrochemical Society.
Effect of top electrode material on resistive switching properties of ZrO2 film memory devices
(2007-05-01)
Lin, Chih-Yang
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Wu, Chen-Yu
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Wu, Chung-Yi
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Lee, Tzyh-Cheang
;
Yang, Fu-Liang
The influence of top electrode material on the resistive switching properties of ZrO2 -based memory film using Pt as a bottom electrode was investigated in this letter. In comparison with Pt/ZrO2/Pt and Al/ZrO2/Pt devices, the Ti/ZrO2/Pt device exhibits different resistive switching current-voltage (I-V) curve, which can be traced and reproduced by a dc voltage more than 1000 times only showing a little decrease of resistance ratio between high and low resistance states. Furthermore, the broad dispersions of resistive switching characteristics in the Pt/ZrO2/Pt and Al/ZrO2/Pt devices are generally observed during successive resistive switching, but those dispersions are suppressed by the device using Ti as a top electrode. The reliability results, such as cycling endurance and continuous readout test, are also presented. The write-read-erase-read operations can be over 104 cycles without degradation. No data loss is found upon successive readout after performing various endurance cycles.
Efficient semitransparent organic solar cells with good color perception and good color rendering by blade coating
(2017-04)
Wong, Ying Qian
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Meng, Hsin-Fei
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Wong, Hin Yong
;
Tan, Ching Seong
;
Wu, Chen-Yu
This paper proposes high efficiency semitransparent organic solar cells (OSCs) with good color perception and good color rendering using blade coating technique. We investigate four different polymer blends and first fabricate small area devices with active area of 0.04 cm(2), followed by large area devices with active area of 10.8 cm(2). Two of the polymer blends, 2,6-Bis(trimethyltin)-4,8-bis(5-(2-ethylhexyl) thiophen-2-yl)benzo[1,2-b:4,5-b\']dithiophene:6,6-phenyl C71-butyric acid methyl ester (PBDTTT-CT:PC71BM) and poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b;4,5-b\'] dithiophene-2,6-diyl-alt-(4-( 2-ethylhexyl)-3-fluorothienof 3,4-b Ithiophene-)-2-carboxylate-2-6-diyl)]: PC71BM (PBDTT-EFT:PC71BM) show promising results. For small area devices, semitransparent PBDTIT-CT:PC71BM and semitransparent PBDTIT-EFT:PC71BM achieve a power conversion efficiency (PCE) of 5.2% (opaque PCE = 7.5%) and 5.6% (opaque PCE = 9.4%) respectively. For large area devices, they are found to produce a PCE of 3.8% (opaque PCE = 4.2%) and 5.3% (opaque PCE = 5.9%) respectively. Based on the CIE 1931 chromaticity diagram, semitransparent PBDTIT-CT:PCTIBM and semitransparent PBITITT-EFT:PCTIBM are located very close to the standard illuminant D65, indicating good color perception. As for color rendering, they demonstrate high color rendering index (CR1) of 95.4 and 87.1 respectively. These combined high performances indicate high-quality transmitted light, which is suitable for window application. (C) 2017 Published by Elsevier B.V.
Memory effect of RF sputtered ZrO2 thin films
(2007-12-03)
Lin, Chih-Yang
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Wu, Chung-Yi
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Wu, Chen-Yu
;
Lin, Chun-Chieh
;
Tseng, Tseung-Yuen
Electrical properties of RF sputtered ZrO2 Memory thin films were investigated in this study. The device with structure AI/ZrO2/Pt shows a reproducible resistive switching behavior traced over 100 times at room temperature. Moreover, by using various top electrodes, such as Pt, Cu, Ni, Ag, Ti, and even W-probe, the resistive switching phenomenon can be observed in ZrO2-based memory with Pt bottom electrode, indicating that the ZrO2 bulk dominates the resistive switching. The bias polarity dependent resistive switching behavior is demonstrated in the Ti/ZrO2/Pt device, which might be due to interface reaction between Ti and ZrO2 film. The resistance value of high conductive state in the Ti/ZrO2/Pt device decreases with increasing current compliance implying the possibility for multi-bit storage. Besides, the Ti/ZrO2/Pt device can be operated over 2000 resistive switching cycles at 85 degrees C by sweeping DC voltage, and the two memory states demonstrate good stability under read voltage stress at room temperature and 95 degrees C. The write-read-erase-read operations can be over 10(3) cycles at 85 degrees C. No data loss is found upon successive readout before and after performing 10(3) endurance cycles at 85 degrees C. According to above experimental results, the ZrO2 thin film has high potential for nonvolatile memory application. (C) 2007 Elsevier B.V. All rights reserved.
Modified resistive switching behavior of ZrO2 memory films based on the interface layer formed by using Ti top electrode
(2007-11-01)
Lin, Chih-Yang
;
Wu, Chung-Yi
;
Wu, Chen-Yu
;
Tseng, Tseung-Yuen
;
Hu, Chenming
The influence of Ti top electrode material on the resistive switching properties of ZrO2-based memory film using Pt as bottom electrode was investigated in the present study. When Ti is used as top electrode, the resistive switching behavior becomes dependent on bias polarity and no current compliance is needed during switching into high conducting state. This phenomenon is attributed to the fact that a series resistance between Ti and ZrO2 film, composed of a TiOx layer, a ZrOy layer, and even the contact resistance, imposed a current compliance on the memory device. Besides, our experimental results imply that switching the device into high conducting state is a field driven process while switching back into low conducting state is a current driven process. (c) 2007 American Institute of Physics.