本研究以真空蒸鍍與水蒸氣熱氧化法（Rheotaxial growth and thermal oxidation with water vapor）製備氧化鎵薄膜氣體感測器，藉由改變氧化時間1.5～24小時與在不同氫氮混合氣氛(10~100sccm氫氣/100sccm氮氣)下蝕刻反應處理10~90分鐘來探討其表面型態、晶態結構、氧空缺相對濃度、元素比例以及感測性質之變化。
由SEM結果發現氫氣會與氧化鎵產生反應，侵蝕薄膜微結構，破壞表面片狀堆疊。XRD分析顯示氫氣處理後晶相仍維持β-Ga2O3。由光致螢光光譜分析發現以100sccm氫氣/100sccm氮氣之混合氣蝕刻反應處理20分鐘，可獲得最高的氧空缺濃度，但過度的氫氣處理，反而使氧化鎵薄膜厚度被反應消耗掉，減少氧空缺總量。根據酒精感測結果發現氧化1.5小時，再經100sccm氫氣/100sccm氮氣之混合氣蝕刻反應處理10～30分鐘之試片，其感測起始操作溫度降低至195~225℃，可減少感測器運作的能源損耗。在氮氣/酒精氣氛下進行感測比在空氣/酒精氣氛下可提升感測度，推測可能是少了氧氣去抓晶格氧原子與酒精反應所釋放的電子及與氧空缺結合時去吸收的電子，因此在氮氣/酒精氣氛中氣體感測機制比較接近氧空缺機制。

In this study, Ga2O3 thin film gas sensor was prepared by rheotaxial growth and thermal oxidation (RGTO) with water vapor. By changing the oxidation time from 1.5 to 24hr and treating under various H2 concentration of H2 and N2 gas mixture (10~100sccm H2/100sccm N2) for 10 to 90 minutes, the surface morphology, crystalline structure, the relative concentration of oxygen vacancies, the O/Ga element ratio, and the sensing properties, were investigated.
The SEM results showed that the hydrogen reacts with Ga2O3 thin film, leading to a damage of the microstructure such as the destruction of the sheet stack . XRD analysis showed that the crystalline phase remains unchanged, i.e., β-Ga2O3 after the hydrogen treatment. Photoluminescence spectrum analysis showed that the treatment with 100sccm H2/100sccm N2 for 20 minutes leads to the highest concentration of oxygen vacancies. However, an excessive hydrogen treatment will etch away the gallium oxide film to reduce the total amount of oxygen vacancies.The sensing experimental results showed that oxidizing Ga film for 1.5hr and then treating with 100sccm H2/100sccm N2 for 10 to 30 minutes results in a Ga2O3 film with an operating temperature decreasing to 195~225℃. The sensitivity in the nitrogen/ethanol atmosphere is much better than that in the air/ethanol atmosphere. The reason may be resulted from that no oxygen capture the electrons released by the reaction of the ethanol and lattice oxygen and absorb the electrons during the refilling of oxygen vacancy. Therefore, the underlying gas sensing mechanism in the nitrogen/ethanol atmosphere can be explained by the oxygen-vacancy model.

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