砷化鎵被廣泛應用於半導體產業，然而在大量製造砷化鎵晶圓的過程中，會有許多砷化鎵蝕刻廢液產生。為了達到永續經營及循環經濟之目的，本研究將針對砷化鎵蝕刻廢液進行處理。本研究可分為兩大部分，第一部分以溶媒萃取法從砷化鎵模擬蝕刻廢液當中回收高純度的氯化鎵水溶液，並沉澱砷離子；第二部分將再生所獲得的氯化鎵水溶液應用於GZO薄膜合成。
第一部分萃取階段中，氯化鎵和硫化砷粉末被溶於氨水中，以用來模擬砷化鎵蝕刻廢液。而Cyanex 272以煤油稀釋至0.5 M並在pH 2、油水比為0.1、萃取時間為5分鐘的條件下，與模擬蝕刻廢液進行萃取反應，萃取效率可達到77.4%，透過四階的多階萃取，萃取效率可提升到99.5%。萃取完成後，會添加硫酸鐵粉末至富含砷離子的萃餘液當中，並在95℃、Fe/As比為10的條件下，將99.9%的砷離子沉澱，以達到環保署的放流水標準。反萃取階段中，0.5 M 的鹽酸被用來將油相中的鎵離子反萃取成氯化鎵水溶液。在油水比為1、反萃取時間為3分鐘的條件下，反萃取效率達到97.5%，氯化鎵水溶液純度可達99.95%。而氯化鎵水溶液中的鎵離子濃度與砷化鎵模擬蝕刻廢液相比，濃縮了約7倍。
第二部分GZO薄膜的合成，則以0.5 M的氯化鋅水溶液，摻雜0~5 at.%的鎵離子並添加1mL的介面活性劑後，旋轉塗佈於玻璃基板上。在600℃退火後，以X光繞射儀分析確認其為氧化鋅結構、掃描式電子顯微鏡觀察其表面型態與平整度、紫外光-可見光分光光譜儀分析可見光範圍的薄膜光穿透率。最終，GZO透明導電薄膜在3 at.%的摻雜率下擁有最佳的平整度，光穿透率在可見光範圍可達到90%以上。

This study aims to construct an eco-friendly circular economy system that recovers gallium chloride solution from waste GaAs etching solution and reuses in GZO thin films synthesis. This study divides into two parts, which is gallium extraction and GZO thin films synthesis. In the first part, the simulated GaAs etching solution was extracted using 0.5M Cyanex 272 at pH 2, 0.1 O/A ration for 5 min. The extraction efficiency was 77.5% which had the optimal ratio of concentration. The efficiency was improved to 99.5% through four steps extraction. In order to precipitate arsenic ions from the raffinate, the iron sulfate heptahydrates were added and 99.9% arsenic ions were precipitated when Fe/As ratio was 10. After extraction, the organic phase was stripped using 0.5M HCl at 1 O/A ratio for 3 min, the stripped efficiency attained 97.5%. The purity of recovered gallium chloride solution was 99.95% and the gallium was seven times the concentration of the simulated etching solutions. In the second part, GZO thin films were synthesized with 0.5M zinc chloride aqueous solution, 1 mL surfactant, and were doped with 0~5 at.% gallium. The precursor was coated on the glass substrate by spin coating and annealed at 600℃. Finally, the GZO thin film doped with 3 at.% gallium had an optimal surface and outstanding transmittance. The transmittance was higher than 90% in the visible region.

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