本論文在研究氧化鎂鎳材料，並且將其用來作為電阻式隨機存取記憶體的氧化層以及氣體感測器的感測層。
首先我們介紹氧化鎂鎳材料的製程並配合穿透式電子顯微鏡(TEM)分析元件結構以及薄膜的繞射狀況，並藉由原子力顯微鏡(AFM)分析薄膜表面粗糙度，最後藉著X射線光電子能譜(XPS)分析薄膜內的氧空缺數量，得知氧空缺隨著元素摻雜變化的狀況。
對於RRAM的研究，我們以不同元素比例以及不同氬氧比例濺鍍氧化鎂鎳薄膜作為電阻轉換層，並且探討使用金屬上電極Ag、Ni、Ti之下，氧化鎂鎳記憶體的製備以及電特性。對於銀上電極而言，量測結果顯示元件有著雙極性的特性，由於銀有著高自由能，RRAM元件有著極低的Set與Reset電壓，並且操作次數能夠達到1500次以上，其中使用氧空缺較多的薄膜會有著較佳的特性，能夠使on/off ratio明顯上升。而使用Ni作為上電極之後，元件開關次數較低，使用氧空缺較少的薄膜特性最好，但也僅能操作400多次，不過比起其他金屬上電極有著最大的on/off ratio。而對於Ti上電極的元件有著2000多次的操作次數，並且由於純粹藉由氧空缺燈絲傳導，在氧空缺較低時會更容易斷裂並且造成更大的on/off ratio。在量測完之後我們試著對量測結果進行分析並建立導電燈絲模型，接著嘗試對元件進行改善。
隨後我們試著改善元件，首先先降低元件的限電流，在限電流較低的情況下燈絲也會較細，在Ni與Ti上電極的元件中呈現較佳的特性。最後我們將RRAM的電阻轉換層進行堆疊，上下層使用不同參數的氧化鎂鎳薄膜製作出雙層RRAM，能夠幫助導電燈絲形成，上電極選用Ni與Ti，經過量測發現雙層結構使得元件的開關次數更進一步的上升，達到了2500~3000次的開關次數。
另一部分，我們氧化鎂鎳薄膜製作氣體感測器，與常見的氧化鎳氣體感測器比較起來隨著鎂比例的提升我們確實改善了感測器對於NO2氣體的響應度，使用Mg0.5Ni0.5O薄膜有著最佳的響應度並有不錯的選擇性，這是由於氧空缺的提升以及薄膜電阻的變化，使的響應度因此而提升，而在Mg比例繼續上升後由於鎂的比例過高而對於NO2反而沒有了響應，並且我們將Mg0.5Ni0.5O薄膜實作在MEMS結構上，不過穩定性還不足因此放在future work中。

We studied the MgxNi1-xO material in this paper and used it as the oxide layer of resistive random-access memory and the sensing layer of gas sensors.
First, we introduce the manufacturing process of the MgxNi1-xO material. We analyzed the structure of the device and the diffraction condition of the film with a transmission electron microscope (TEM). Second, analyze the surface roughness of the film by atomic force microscope (AFM). Finally, we analyzed the amount of oxygen vacancies in the film by X-ray photoelectron spectroscopy (XPS) and obtained the status of oxygen vacancies changing with element doping.
For RRAM research, we sputtered MgxNi1-xO thin films with different element ratios and different oxygen flow ratios as the resistance conversion layer. And then we discussed the electrical characteristics of RRAM using metal upper electrodes Ag, Ni, Ti. For the Ag upper electrode, the measurement result shows that the device has bipolar characteristics. Because of the high free energy of silver, the RRAM device has extremely low Set and Reset voltages, and the number of operations can reach more than 1500 times. Among them, the RRAM with more oxygen vacancies in the film will have better characteristics and can significantly increase the on/off ratio. Subsequently, using Ni as the upper electrode, the number of elements switching times is lower than Ag upper electrode RRAM. Among them, the RRAM film of fewer oxygen vacancies has the best feature. Although it can only be operated for 400 times, it has the largest on/off ratio compared to other metal upper electrodes. For the Ti upper electrode element, there are more than 2,000 switching cycle times. And since it is conducted purely by the oxygen vacancy filament, when the oxygen vacancy is low, the filament will be easier to break and cause a greater on/off ratio. After the measurement, we tried to analyze the measurement results and build a conductive filament model, and then tried to improve the components.
Then we tried to improve the components. First, we lowered the compliance current of the components. In the case of lower compliance current, the filament will be thinner, showing better characteristics in the RRAM with Ni and Ti upper electrodes. Finally, we stack the resistance conversion layers of the RRAM, the upper and lower layers use MgxNi1-xO films with different parameters to make a bilayer RRAM, which can help the formation of the conductive filament, and the top electrode of the bilayer RRAM selects Ni and Ti. After measurement, it is found that the bilayer structure further increases the switching times of the component, reaching 2500~3000 switching times.
In the other part, we made gas sensors with MgxNi1-xO thin film. Compared with common NiO gas sensors, with the increase of Mg ratio, we have indeed improved the sensor's response to NO2 gas. The use of Mg0.5Ni0.5O film has the best response and good selectivity. This is due to the increase in oxygen vacancy and the change in film resistance, which improves the responsivity. After the Mg ratio continues to rise, too much Mg ratio makes the sensor no longer respond to NO2. And we made the Mg0.5Ni0.5O film with the MEMS structure, but the stability is not enough, so it is placed in the future work.

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