Fig-4.2-8 depicts the width between reset and set is extended.
1 2 3 4 5
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Fig-4.2-9 indicates a special phenomenon which the on/off ratio is enlarged with the a-region lengthening gradually.
Fig-4.3-1 depicts the endurance of different reset width. And the 300ns and 900ns effects possess some different phenomenon which is the 900ns possesses higher instable than the 300ns.
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Fig-4.3-2 depicts the different width phenomenon affects the state of device because the unnecessary energy can influence the stability of device.
Fig-4.4-1 indicates the STD device can achieve 10
7times operating times and
the on/off ratio can keep one order and stable.
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Chapter 5
Conclusion
In this section, we will conclude three chapters in the thesis. In Chapter2, we can observe the structure of Pt/DMO/TiN possesses resistive switching behavior. Our device has some oxygen vacancies through the analysis of XPS in the DMO film. And the thickness of DMO film is 12nm by TEM cross-section. The device is taken to test the reliability of device. Therefore, we can also observe the endurance and retention of the STD device. The retention of device maintains 104 second at 850C high temperature so it means the device on or off state can store ten years without power.
We can also see the AC and DC endurance test are good characteristic and it means the on/off ratio can maintain one-order at 105 and 100 times of operating, respectively and.
In chapter3, the NDR phenomenon is discovered at the current-voltage of DMO device. First, the IV curve is analyzed before forming process and temperature, constant voltage sampling and the film thickness effect influence the NDR voltage changing. The reason is that the oxygen ions accumulate near the interface and form an oxygen-rich region causes the NDR phenomenon. In other words, the NDR is interface effect. Second, the IV curve is analyzed after forming. In the same polarization, the NDR phenomenon is also discovered but the characteristic imply a sub-RRAM switching behavior. In fact, the oxygen ions affect the device and cause the NDR phenomenon is after forming process. Therefore, we think the phenomenon that the oxygen ions accumulate near interface has existed in DMO film. And the sub-RRAM and original-RRAM represent interface switching mechanism and filament switching mechanism, respectively. However, we cannot see a forming-free
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switching behavior because the thickness of STD device is too thin to avoid breakdown. Subsequently, we can see the forming-free switching behavior when the film thickness is thick. The thick device verifies the oxygen ion model and our conjecture and the switching characteristic is interface switching mechanism. There is still the other evidence to verify the oxygen ion model in the double layer device (i.e.
the DMON device) because the nitrogen attract to the oxygen ions. We can observe the huge NDR phenomenon exist in DMON device.
In chapter4, first, the reset time is changed with temperature by pulse IV. On the other hand, the reset speed is increased with increasing temperature due to the oxygen ions effect. Second, the endurance test is changed by inputting the amount of pulse cycles per time. In order to solve the problem, we change the pulse condition and then see the state of STD device. Therefore, we think the phenomenon cause from the time of recombination and heating effect. Finally, we test an optimized condition and then the condition can make the endurance test of device achieves 107 times and on/off ratio can maintain stale state.
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Resume
姓名：黃偉立 (Wei-Li Huang)
出生日期：民國七十五年九月十八日
住址：300 屏東市前進里清進巷 139-9 號
學歷：
國立屏東教育大學 應用物理學系 學士 (2005.09~2009.01)
國立交通大學 電子研究所 碩士 (2009.09~2011.06)
論文題目：
新穎材料 DyMn2O5在電阻式記憶體上的機制研究與應用
The Researching Mechanism and Application of the Novel Material DyMn2O5 (DMO) in Resistive Random Access Memory