溶膠凝膠法製備InGaZnO4透明導電薄膜的光電性質研究

Abstract

本論文研究之IGZO透明導電薄膜是使用溶膠凝膠(sol-gel)法來製造，此方式是利用旋轉塗佈技術來沉積IGZO薄膜，並且可以在常壓常溫下來形成IGZO薄膜；相較於真空濺鍍系統(RF sputter)，旋轉塗佈技術可以大面積來製造薄膜，以節省製程時間與降低成本。 本實驗是以硝酸銦、硝酸鎵和醋酸鋅為前驅物(precursors)配製成2M的IGZO溶液，其莫耳比為1:1:2、3:1:2和5:1:2，使用2-甲氧基乙醇(2-ME)為溶劑，單乙醇胺(MEA)為穩定劑，並在60℃攪拌4小時以合成溶膠，經過24小時的老化處理，使溶膠中的粒子鍵結成網狀分子，形成凝膠。在IGZO薄膜塗佈之後，藉由熱處理來改善IGZO薄膜的光電特性，並且利用改變熱處理溫度、氣氛以及摻雜比例來找出最好的條件。實驗所製備之IGZO透明導電薄膜的最佳熱處理條件為二階段熱處理，第一階段熱處理為400℃在Ar氣氛下熱處理一小時；第二階段熱處理為350℃在(10%H2+90%N2)氣氛下熱處理一小時，其片電阻值為462.06Ω/□，透光率為85%。實驗結果顯示，適當地調控摻雜離子的比例與熱處理條件，有助於降低薄膜的導電性及提升薄膜的透光率。

IGZO transparent conducting thin films has been successfully fabricated by sol-gel method. With spin-coating deposition technology at ambient enviroment. In comporision with vaccum systems, spin-coating method is very promising technique for producing large scale thin films in cost-effective and less time-consuming way. In this study, the IGZO precursor solution was prepared by dissolving indium nitrate hydrate, gallium nitrate hydrate, and zinc acetate dehydrate in 2-methoxyethanol and monoethanolamine, and the resultant solution was stirred at 60 ℃ for 4hrs to form the IGZO sol solution. The mole ratio of In : Ga : Zn in IGZO sol solution was varied between 1:1:2, 3:1:2,and 5:1:2. The IGZO sol solution was aged 24 hrs at room temperature to form the IGZO gel solution. After we fabricated IGZO thin film by spin coating, we improve optical and electrical properties the IGZO thin films by using different working temperature, atmosphere and ionic doping ratio. We have successfully produced lowest sheet resistance 462.06 Ω /□ and optical transmission 85% IGZO thin films with two step heat treatment. At first, the films were annealed at 400 ℃ for 1 hr in argon environment. Then, the films were annealed at 350 ℃ for 1 hr in (10%H2+90%N2) environment. The result of experiment shows that the conductivity of IGZO films decrease and the optical transmission of IGZO films is promoted by exactly doping ionic ratio and using ideal working temperature.