Browsing by Author "Deng, Ning"

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Conduction Mechanism and Improved Endurance in HfO2-Based RRAM with Nitridation Treatment
(2017-10-26)
Yuan, Fang-Yuan
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Deng, Ning
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Shih, Chih-Cheng
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Tseng, Yi-Ting
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Chang, Ting-Chang
A nitridation treatment technology with a urea/ammonia complex nitrogen source improved resistive switching property in HfO2-based resistive random access memory (RRAM). The nitridation treatment produced a high performance and reliable device which results in superior endurance (more than 10(9) cycles) and a self-compliance effect. Thus, the current conduction mechanism changed due to defect passivation by nitrogen atoms in the HfO2 thin film. At a high resistance state (HRS), it transferred to Schottky emission from Poole-Frenkel in HfO2-based RRAM. At low resistance state (LRS), the current conduction mechanism was space charge limited current (SCLC) after the nitridation treatment, which suggests that the nitrogen atoms form Hf-N-Ox vacancy clusters (V-o(+)) which limit electron movement through the switching layer.
Engineering interface-type resistance switching based on forming current compliance in ITO/Ga2O3: ITO/TiN resistance random access memory: Conduction mechanisms, temperature effects, and electrode influence
(2016-10-31)
Pan, Chih-Hung
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Chang, Ting-Chang
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Tsai, Tsung-Ming
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Chang, Kuan-Chang
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Chen, Po-Hsun
In this paper, an ITO/Ga2O3: ITO/TiN structured resistance random access memory is introduced. Either interface or filament conduction mechanism can be induced depending on the forming compliance current, which has not been investigated before. Material analyses and electrical I-V measurements on this ITO/Ga2O3: ITO/TiN have also been carried out. The interface conduction mechanism was confirmed by a size-effect experiment, where resistance varied inversely to via size. In addition, the current fitting results show that Schottky emission dominates the on-and off-state currents. All physical mechanisms of device resistive switching behaviors are explained by our models and also confirmed by I-V characteristics. Published by AIP Publishing.
Resistance Switching Characteristics Induced by O-2 Plasma Treatment of an Indium Tin Oxide Film for Use as an Insulator in Resistive Random Access Memory
(2017-01-25)
Chen, Po-Hsun
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Chang, Ting-Chang
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Chang, Kuan-Chang
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Tsai, Tsung-Ming
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Pan, Chih-Hung
In this study, an O-2 inductively coupled plasma (ICP) treatment was developed in order to modify the characteristics of indium tin oxide (ITO) film for use as an insulator in resistive random access memory (RRAM). After the O-2 plasma treatment, the previously conductive ITO film is oxidized and becomes less conductive. In addition, after capping the same ITO material for use as a top electrode, we found that the ITO/ITO (O-2 plasma)/TiN device exhibits very stable and robust resistive switching characteristics. On the contrary, the nontreated ITO film for use as an insulator in the ITO/ ITO/TiN device cannot perform resistance switching behaviors. The material analysis initially investigated the ITO film characteristics with and without O-2 plasma treatment. The surface was less rough after O-2 plasma treatment. However, the molar concentration of each element and measured sheet resistance results for the O-2-plasma-treated ITO film were dramatically modified. Next, electrical measurements were carried out to examine the resistance switching stability under continuous DC and AC operation in this ITO/ITO(O-2 plasma)/TiN device. Reliability tests, including endurance and retention, also proved its capability for use in data storage applications. In addition to these electrical measurements, current fitting method experiments at different temperatures were performed to examine and confirm the resistance switching mechanisms. This easily fabricated device, using a simple material combination, achieves excellent performance by using ITO with an O-2 plasma treatment and can further the abilities of RRAM for use in remarkable potential applications.
Ultralow Power Resistance Random Access Memory Device and Oxygen Accumulation Mechanism in an Indium-Tin-Oxide Electrode
(2016-12)
Pan, Chih-Hung
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Chang, Ting-Chang
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Tsai, Tsung-Ming
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Chang, Kuan-Chang
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Chu, Tian-Jian
This paper proposes low power consumption resistance random access memory (RRAM) devices with indium-tin-oxide (ITO) electrodes. The development of the Internet of Things (IoT) is a trend in future technology, but the bottleneck in IoT development is high power consumption; therefore, targeting low-power-consumption memory is crucial for the IoT. ITO-capped RRAM devices have been shown to exhibit outstanding performance and low power consumption, and here, we propose an oxygen accumulation mechanism by analyzing device characteristics. We find that the conduction current mechanism will be affected by oxygen absorbance in the ITO electrode. During the forming and set processes, oxygen ions will be propelled into the ITO electrode due to its oxygen vacancy-rich property; therefore, we find Schottky emission both at high-resistance state and low-resistance state and that the device exhibits an automatic current compliance property. Varied stop-voltage measurements were carried out to verify the device mechanism. Because of its capability for oxygen storage, the thick ITO layer was confirmed to affect the characteristic due to a difference in oxygen gradient. A new structure and novel material are proposed, based on the devices with ITO electrodes to improve performance and reduce power consumption.