本論文主要為透過射頻濺鍍法成長之氧化鎵及透過共濺鍍法成長之氧化鎵系列氧化物半導體的研究及應用。氧化鎵本身為透明材料，適合作為光敏元件，並且在溶液中的耐久性十分良好，故而能夠做為光電化學水分解之電極。並且由於其內在的高電阻特性，以及對氧氣具有非常敏感的電導率，對電阻式隨機存取記憶體(RRAM)來說，也為一種良好材料。而氧化鎵的能隙寬度為4.9電子伏特，其對應的偵測波長為250奈米，故而可以期待氧化鎵系列氧化物半導體應用於深紫外光的偵測運用，使其不僅可以成為薄膜電晶體的主動層，更可以變身為紫外光吸光層運用於光偵測器上。
在我的實驗一中，利用氧化鎵薄膜其透明且良好的溶液耐久特性，作為光電化學水分解的光電極，在寬能隙的條件下，透過短波長紫外光照射，以產生氫氣之綠色能源，並且通過不同的氧分量調控氧化鎵薄膜，探討在不同狀態下的入射光子轉換效率等。
在第二個實驗裡，則是透過氧化鎵薄膜其高電阻特性，作為電阻式隨機存取記憶體的研製，並且通過不同氧分量比例試驗出其記憶體特性，可以發現唯有在特定比例的氧分量中，才能表現出良好的記憶體特性，從實驗可以得到氧分量為25%之記憶體，其開關電流比能達到105以上，並且擁有200次以上的切換次數及104秒的開關維持時間，而其設置(set)與重置(reset)的電阻切換現象能夠以空間電荷限制電流機制與歐姆接觸來表示。
第三個實驗中，我們通過共濺鍍法，選擇氧化鎵與氧化銦共濺鍍而成的混合氧化物半導體材料，運用於薄膜電晶體元件上。而混合出的氧化銦鎵薄膜被製備成薄膜電晶體的主動層，通過改變氧化銦的瓦數，量測不同混合比例下的元件電特性，並且在最佳電特性的比例下，再通過不同氧分量比例來觀察其電特性及光特性之改變。從實驗可以得到良好的電特性，在外偏壓8伏特的量測條件下，臨限電壓、次臨限擺幅、電流開關比分別為 0.83 V、0.14 V/decade、~103。此元件同樣也被測試其紫外光感測能力，在外偏壓-1伏特的量測條下，對應的紫外光對可見光拒斥比及光響應分別為1.12×104及0.34A/W。

This thesis mainly focuses on the research and application of Ga2O3 deposited by RF sputtering and Ga2O3-based oxide semiconductors deposited by co-sputtering. Ga2O3 is a transparent material, suitable as a photosensitive element, and it has an excellent durability in solution. Therefore, it can be used in photoelectrochemical water decomposition of the electrode. Moreover, the inherent high resistance characteristics and very sensitive conductivity to oxygen of Ga2O3 make it also be a good material for Resistive Random Access Memory (RRAM). Ga2O3 has the wide bandgap energy width of 4.9 electron volts, and its corresponding detection wavelength is 250 nanometers. Therefore, the Ga2O3-based oxide semiconductors are not only applied in the thin film transistors as active layers but also used for the ultraviolet sensor devices as absorption layers.
In my first experiment, using the transparent property and excellent solution durability of Ga2O3 film as a photoelectrode of photoelectrochemical water-splitting. Under a wide bandgap condition, using the short-wavelength UV light to irradiated the photoelectrode, and the hydrogen would be generated in the water splitting. Moreover, we used different oxygen content to regulate Ga2O3 film, and explore the incident photon conversion efficiency under different states.
In the second experiment, the inherent high resistance characteristics of the Ga2O3 thin film was used as a resistive random access memory. Moreover, the memory characteristics of the Ga2O3 film were tested by different oxygen content. We found that only in a specific ratio can exhibit the good memory characteristics . From the experiment, a memory with an oxygen component of 25% has the best performance among these samples. It can be found that it has bipolar resistance switch characteristics, its switching current ratio was more than 105 times. The switching cycle could be up to 200 times. And the retention time was about 104 seconds. The Set and Reset processes are primarily affected by the conduction mechanism of the ohmic and space charge limited current.
In the third experiment, demonstrating thin film transistor on SiO2/Si substrate with IGO oxide semiconductors by co-sputtering using Ga2O3 and In2O3 targets at room temperature. The mixed IGO thin film is applied as the active layer of the thin film transistor. By changing the wattage of In2O3, the electrical characteristics of the device at different mixing ratios are measured. In addition, at the In2O3 content of the optimal electrical characteristics, also using different proportions of oxygen contents to observe the variety of their electrical and optical properties. The fabricated device presents excellent electrical characteristics. Under the condition of 8V external bias measurement, the threshold voltage, sub-threshold slope, and the On/Off current ratio are 0.83 V, 0.14 V/decade, and ~103, respectively. This device was also tested for its UV sensing capability. Under the external bias -1V, the UV-to-visible rejection ratio and photoresponsivity are 1.12×104 and 0.34 A/W.

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