Browsing by Author "Wang, Sheng-Yu"

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Controllable oxygen vacancies to enhance resistive switching performance in a ZrO(2)-based RRAM with embedded Mo layer
(2010-12-10)
Wang, Sheng-Yu
;
Lee, Dai-Ying
;
Huang, Tai-Yuen
;
Wu, Jia-Woei
;
Tseng, Tseung-Yuen
In this study, the resistive switching characteristics of a ZrO(2)-based memory film with an embedded Mo layer are investigated. The experimental results show that the forming process can be removed by inserting an embedded Mo metal layer within ZrO(2) via a post-annealing process. The excellent memory performance, which includes lower operation voltage (<1.5 V), good endurance (>10(3) cycles), a stubborn nondestructive readout property (>10(4) s), and long retention time (>10(7) s), is also demonstrated. Moreover, high-speed operation (10 ns) can be successively maintained over 10(3) cycles without any operational errors observed in this memory device. Due to the interface layer induced by the Ti top electrode, the formation and rupture of conducting filaments are suggested to occur near the Ti/ZrO(2) interface. The oxygen vacancies induced by the embedded Mo can enhance the formation of conducting filaments and further improve the switching characteristics in ZrO(2)-based devices.
Controllable oxygen vacancies to enhance resistive switching performance in a ZrO2-based RRAM with embedded Mo layer
(2010-12-10)
Wang, Sheng-Yu
;
Lee, Dai-Ying
;
Huang, Tai-Yuen
;
Wu, Jia-Woei
;
Tseng, Tseung-Yuen
In this study, the resistive switching characteristics of a ZrO2-based memory film with an embedded Mo layer are investigated. The experimental results show that the forming process can be removed by inserting an embedded Mo metal layer within ZrO2 via a post-annealing process. The excellent memory performance, which includes lower operation voltage (<1.5 V), good endurance (>10(3) cycles), a stubborn nondestructive readout property (>10(4) s), and long retention time (>10(7) s), is also demonstrated. Moreover, high-speed operation (10 ns) can be successively maintained over 10(3) cycles without any operational errors observed in this memory device. Due to the interface layer induced by the Ti top electrode, the formation and rupture of conducting filaments are suggested to occur near the Ti/ZrO2 interface. The oxygen vacancies induced by the embedded Mo can enhance the formation of conducting filaments and further improve the switching characteristics in ZrO2-based devices.
DC Characteristics of InAlAs/InGaAsSb/InGaAs Double Heterojunction Bipolar Transistors
(2010-12-01)
Chen, Shu-Han
;
Chang, Chao-Min
;
Chiang, Pei-Yi
;
Wang, Sheng-Yu
;
Chang, Wen-Hao
DC electrical characteristics of a series of InAlAs/InGaAsSb/InGaAs double heterojunction bipolar transistors (DHBTs) that are grown on InP by molecular beam epitaxy are reported and analyzed. The InGaAsSb base of the transistors leads to a type-I base-emitter junction and a type-II base-collector junction, resulting in unique device characteristics, such as low turn-on voltage, low crossover current, and constant current gain over a wide current range. In addition, the DHBTs exhibit rather high current gains despite the use of a heavily doped thick InGaAsSb base layer. This indicates the long minority carrier lifetime of the InGaAsSb material. A high current gain over base sheet resistance ratio is, thus, realized with these novel DHBTs.
Effects of Ti top electrode thickness on the resistive switching behaviors of rf-sputtered ZrO(2) memory films
(2009-09-14)
Wang, Sheng-Yu
;
Lee, Dai-Ying
;
Tseng, Tseung-Yuen
;
Lin, Chih-Yang
;
電子工程學系及電子研究所
In this study, we propose a simple method to produce the various interface thicknesses within Ti/ZrO(2) by changing the thickness of the Ti top electrode. As the Ti thickness increases, the induced interface thickness also increases to degrade the dielectric strength of the ZrO(2), further lowering the forming voltage. However, when the interface layer is thick enough, it will trap sufficient charges to build up an opposite electric field to increase the forming voltage. The induced interface thickness is found to obviously affect the bias polarity of the resistive switching behavior and the device reliability. A fluctuant ON process is also demonstrated to be attributed to the competition between the formation and rupture of the conducting filaments. (C) 2009 American Institute of Physics. [doi: 10.1063/1.3231872]
Effects of Ti top electrode thickness on the resistive switching behaviors of rf-sputtered ZrO2 memory films
(2009-09-14)
Wang, Sheng-Yu
;
Lee, Dai-Ying
;
Tseng, Tseung-Yuen
;
Lin, Chih-Yang
;
電子工程學系及電子研究所
In this study, we propose a simple method to produce the various interface thicknesses within Ti/ZrO2 by changing the thickness of the Ti top electrode. As the Ti thickness increases, the induced interface thickness also increases to degrade the dielectric strength of the ZrO2, further lowering the forming voltage. However, when the interface layer is thick enough, it will trap sufficient charges to build up an opposite electric field to increase the forming voltage. The induced interface thickness is found to obviously affect the bias polarity of the resistive switching behavior and the device reliability. A fluctuant ON process is also demonstrated to be attributed to the competition between the formation and rupture of the conducting filaments. (C) 2009 American Institute of Physics. [doi: 10.1063/1.3231872]
Improved resistive switching properties of Ti/ZrO(2)/Pt memory devices for RRAM application
(2011-07-01)
Wang, Sheng-Yu
;
Tsai, Chen-Han
;
Lee, Dai-Ying
;
Lin, Chih-Yang
;
Lin, Chun-Chieh
In this study, we have investigated the effect of current compliance during forming process on resistive switching (RS) characteristics of the Ti/ZrO(2)/Pt device. The higher the current compliance is, the larger RS operation voltage is needed. The Ti/ZrO(2)/Pt device with high device yield can be operated over 10,000 RS cycles by sweeping dc voltage. and the on and off two memory states exhibit good stability under 0.3 V stress voltage. Moreover, the data retention of both memory states is over 10(5) s. As applying +6-V 10-ns and -3-V 10-ns voltage pulses on the device, there are operation errors observed during continuous write-read-erase-read cycles until increasing the pulse width to 50 ns. Nondestructive readout tests are also performed on the Ti/ZrO(2)/Pt device before and after 10(3) pulse cycles without any obvious degradation observed. Compared with reported ZrO(2)-based memory devices, our Ti/ZrO(2)/Pt device exhibits better RS properties and has a high potential for memory application. (C) 2011 Elsevier B.V. All rights reserved.
Improved resistive switching properties of Ti/ZrO2/Pt memory devices for RRAM application
(2011-07-01)
Wang, Sheng-Yu
;
Tsai, Chen-Han
;
Lee, Dai-Ying
;
Lin, Chih-Yang
;
Lin, Chun-Chieh
In this study, we have investigated the effect of current compliance during forming process on resistive switching (RS) characteristics of the Ti/ZrO2/Pt device. The higher the current compliance is, the larger RS operation voltage is needed. The Ti/ZrO2/Pt device with high device yield can be operated over 10,000 RS cycles by sweeping dc voltage. and the on and off two memory states exhibit good stability under 0.3 V stress voltage. Moreover, the data retention of both memory states is over 10(5) s. As applying +6-V 10-ns and -3-V 10-ns voltage pulses on the device, there are operation errors observed during continuous write-read-erase-read cycles until increasing the pulse width to 50 ns. Nondestructive readout tests are also performed on the Ti/ZrO2/Pt device before and after 10(3) pulse cycles without any obvious degradation observed. Compared with reported ZrO2-based memory devices, our Ti/ZrO2/Pt device exhibits better RS properties and has a high potential for memory application. (C) 2011 Elsevier B.V. All rights reserved.
Multilevel resistive switching in Ti/Cu(x)O/Pt memory devices
(2010-12-01)
Wang, Sheng-Yu
;
Huang, Chin-Wen
;
Lee, Dai-Ying
;
Tseng, Tseung-Yuen
;
Chang, Ting-Chang
The multilevel resistive switching (RS) behaviors of the Ti/Cu(x)O/Pt device were investigated by controlling the operated parameters of current and voltage bias in this study. We demonstrated that at least five-level memory states for data storage could be determined by controlling the current compliance, the span of voltage sweeping, and the amplitude of voltage pulse imposed on the memory device. During the dc voltage sweeping mode, not only the multilevel ON-states but also the multilevel OFF-states were achieved for the multilevel storage. The RS mechanism of the Ti/Cu(x)O/Pt device is proposed to be related to the formation/rupture of the conducting filaments, arising from the interfacial oxygen ion migration between the Ti top electrode and Cu(x)O films. Moreover, a possible conduction scenario for the multilevel RS behaviors is also suggested. Owing to all the multilevel memory states are distinguishable and possess the nondestructive readout property, it implies that the Ti/Cu(x)O/Pt device has the promising potential for the future multilevel-capability memory cell application. (c) 2010 American Institute of Physics. [doi:10.1063/1.3518514]
Multilevel resistive switching in Ti/CuxO/Pt memory devices
(2010-12-01)
Wang, Sheng-Yu
;
Huang, Chin-Wen
;
Lee, Dai-Ying
;
Tseng, Tseung-Yuen
;
Chang, Ting-Chang
The multilevel resistive switching (RS) behaviors of the Ti/CuxO/Pt device were investigated by controlling the operated parameters of current and voltage bias in this study. We demonstrated that at least five-level memory states for data storage could be determined by controlling the current compliance, the span of voltage sweeping, and the amplitude of voltage pulse imposed on the memory device. During the dc voltage sweeping mode, not only the multilevel ON-states but also the multilevel OFF-states were achieved for the multilevel storage. The RS mechanism of the Ti/CuxO/Pt device is proposed to be related to the formation/rupture of the conducting filaments, arising from the interfacial oxygen ion migration between the Ti top electrode and CuxO films. Moreover, a possible conduction scenario for the multilevel RS behaviors is also suggested. Owing to all the multilevel memory states are distinguishable and possess the nondestructive readout property, it implies that the Ti/CuxO/Pt device has the promising potential for the future multilevel-capability memory cell application. (c) 2010 American Institute of Physics. [doi:10.1063/1.3518514]
Ti-Induced Recovery Phenomenon of Resistive Switching in ZrO(2) Thin Films
(2010-01-01)
Lee, Dai-Ying
;
Wang, Sheng-Yu
;
Tseng, Tseung-Yuen
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
In this study, we used W-probe directly contacted with the as-deposited ZrO(2) films to perform the resistive switching (RS) phenomenon, and the ZrO(2)-based device finally came to break down (defined as BD-ZrO(2)/Pt device). A remarkable phenomenon called "recovery" was observed, where the RS phenomenon appeared again in a broken ZrO(2)-based device after Ti top electrode deposition. On the contrary, there was no such phenomenon while the Pt and Al top electrodes were deposited on the BD-ZrO(2)/Pt devices. The Ti-induced recovery phenomenon of RS could be explained by the effects of the interface layer formation. The interface layers, TiO(z) and ZrO(y), served as the oxygen reservoir and the series resistance, respectively, to provide sufficient oxygen ions for inducing the redox reaction of the conducting filament near the ZrO(y) layer. Moreover, it also interpreted the high yield of the Ti/ZrO(2)/Pt device. Therefore, the interface engineering of the resistive random access memory device is found very crucial to improve its performance for future commercial applications. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3428462] All rights reserved.
Ti-Induced Recovery Phenomenon of Resistive Switching in ZrO2 Thin Films
(2010-01-01)
Lee, Dai-Ying
;
Wang, Sheng-Yu
;
Tseng, Tseung-Yuen
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
In this study, we used W-probe directly contacted with the as-deposited ZrO2 films to perform the resistive switching (RS) phenomenon, and the ZrO2-based device finally came to break down (defined as BD-ZrO2/Pt device). A remarkable phenomenon called "recovery" was observed, where the RS phenomenon appeared again in a broken ZrO2-based device after Ti top electrode deposition. On the contrary, there was no such phenomenon while the Pt and Al top electrodes were deposited on the BD-ZrO2/Pt devices. The Ti-induced recovery phenomenon of RS could be explained by the effects of the interface layer formation. The interface layers, TiOz and ZrOy, served as the oxygen reservoir and the series resistance, respectively, to provide sufficient oxygen ions for inducing the redox reaction of the conducting filament near the ZrOy layer. Moreover, it also interpreted the high yield of the Ti/ZrO2/Pt device. Therefore, the interface engineering of the resistive random access memory device is found very crucial to improve its performance for future commercial applications. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3428462] All rights reserved.
Unipolar Resistive Switching in ZrO2 Thin Films
(2013-04-01)
Zhang, Guo-Yong
;
Lee, Dai-Ying
;
Yao, I-Chuan
;
Hung, Chung-Jung
;
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