本論文主旨為研究氧化鎂銦材料，並且將其作為紫外光學偵測及氣體感測之元件的感測層。首先，我們將介紹氧化鎂銦材料其製備過程並結合穿透式電子顯微鏡(Transmission electron microscopy)以分析感測元件之結構以及薄膜本身之繞射情況，並使用原子力顯微鏡(Atomic Force Microscope)與掃描電子顯微鏡(Scanning Electron Microscope)去討論氧化薄膜表面的形貌、結構與粗糙度，最後再藉由X射線光電子能譜(X-ray photoelectron spectroscopy)去研究氧化薄膜內的氧空缺以及其元素比例，探討氧空缺隨著製程條件變化的狀況。
針對紫外光學感測器的研究，我們以不同元素比例以及不同的製程氬氧比例濺鍍氧化鎂銦薄膜以作為光學活化層，並且探討在不同操控變因下，氧化鎂銦紫外光感測器之製備以及光電特性。對於鎂銦含量比為2:8與5:5的條件而言，其量測後的數據表明其元件隨著製程氧通量的增加，能隙逐漸變大且表現出更低的暗電流。並在照光後得到了更大的靈敏度。以鎂銦含量比為2:8而言，當濺鍍製程之氬氧流量比達到20%時，其元件靈敏度能達到2.12×104，且有良好的重複性。而對於鎂銦含量比為5:5的條件來說，其元件在濺鍍製程之氬氧流量比為4%時，有最佳的光學特性及3.06×103以上之靈敏度，當氧通量繼續上升，其元件特性即隨之變差，是因為薄膜中有著過量的鎂摻雜時，摻入的氧化鎂增加了薄膜中的氧空缺密度，並在我們通入更多製程氧氣修補缺陷後，導致較弱的鍵結，因此元件受光照時容易斷鍵並影響元件特性，最後導致靈敏度的下降。
另一部分，我們亦使用氧化鎂銦薄膜製作毒害氣體感測器，與常見的氧化銦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Mg0.2In0.8O薄膜有著最佳的響應度並有不錯的選擇性及重複性，這是由於氧空缺的提升以及薄膜電阻的變化，導致了響應度的提升，而在Mg比例繼續上升時，由於鎂元素之比例過高，元件而對於NO2的響應反而變差。
最後，我們在 MEMS 結構上實現了Mg0.2In0.8O薄膜，並用偏壓式的金屬加熱電極取代了傳統的加熱載台階段，以解決載台加熱方式的功率損耗問題以及加熱載台與感應層之間的溫度差異。另外，我們嘗試通過水熱法生長In2O3的奈米結構，以在感測層表面提供更多的氣體吸附位點，進一步增強元件的氣體響應。

The main purpose of this thesis is to study magnesium indium oxide material and use it to be the sensing layer of ultraviolet photodetector sensor and gas sensor.
First, we will introduce the process of magnesium indium oxide material and analyze the structure of the sensor element. Besides, the diffraction of the film itself with transmission electron microscopy. Scanning Electron Microscope was used to discuss the surface structure and surface roughness of the film. Finally, the amount of oxygen vacancies in the film and the element ratio were analyzed by X-ray photoelectron spectroscopy to explore the oxygen vacancies.
For the research on UV optical sensors, we prepared magnesium indium oxide thin films with different element ratios and different process argon-oxygen flow ratios as the optical active layer. Then we discussed the fabrication and optoelectronic characteristics of the devices with different control variable parameters. For the conditions which the ratio of magnesium to indium is 2:8 and 5:5, the measurement results show that as the sputtering process oxygen flux increases, the energy gap of the device gradually becomes larger and shows a lower dark current. When the ratio of magnesium indium content is 2:8 with the oxygen flow ratio of 20%, the sensitivity of the device can reach 2.12×104, and it has good repeatability. Besides, for the condition of magnesium to indium ratio of 5:5, when the argon-to-oxygen flow ratio of the sputtering process is 4%, the device has the best optical characteristics and a sensitivity of more than 3.06×103. When the oxygen flux ratio continues to rise, the device characteristics will deteriorate. There comes a reason, with excessive magnesium doping in the film, the amount of oxygen vacancy density increases. Besides, as processes oxygen getting more and more, the bonding strength of repaired oxygen defects will be weaker and may be easily broken with illuminating, which affects the characteristics of the components, and finally leads to a decrease in sensitivity.
In the other part, we also use magnesium indium oxide film as the sensing layer to make toxic gas sensors. Compared with common indium oxide gas sensors, with the increase of magnesium element ratio, we have improved the sensor's responses and sensitivities to NO2 gas. The Mg0.2In0.8O thin film has the best responsivity, selectivity and good repeatability. The increase of oxygen vacancies and the change of sheet resistance is the reasons which leads to the increase of responsivity. When the proportion of Mg continues to increase, because of the excess proportion of magnesium, the devices show a lower response to NO2.
At the last, we implemented the Mg0.2In0.8O film on the MEMS structure and replaced the traditional heating stage with a biased heating electrode to solve the problems. That are the power loss problem of the heating stage and the heating concerns about the temperature difference between the stage and the sensing layer. Finally, we try to grow single and polycrystalline MgO nanostructures by hydrothermal method to provide more gas adsorption sites on the surface of the sensing layer and further enhance the gas response of the device.

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