水濃度與電解質對氧化鋅薄膜性質之影響

The Influences of Water Content and Electrolytes on the Characterization of Zinc Oxide Thin Film

廖春成(Chun-Cheng Liao)

國立虎尾科技大學/電機資訊學院/光電與材料科技研究所/碩士(2006年)

摘要

本研究主要是藉由溶液化學法來製備氧化鋅薄膜，並探討水濃度與電解質對氧化鋅薄膜結構、結晶性、微結構、及光電特性之影響，且利用摻雜鋁劑量來改善薄膜之導電率及透光率。實驗製程方面，起始材料分別為醋酸鋅及醇溶劑，並以兩種鋁化物為摻雜劑。實驗發現，水濃度及酸性電解質會影響溶液之膠化速率，膠化速率隨水濃度的增加而降低，若增加電解質濃度會增加膠化速率。改變水濃度、酸性電解質、及摻雜鋁劑量對於膠體薄膜的熱活化行為與紅外線光譜並無明顯之影響。當固定溶液濃度時，
摻雜鋁劑量為1.0at%具有較佳的結晶性，當摻雜鋁劑量增加時反而會降低結晶性。經乾燥後的薄膜於熱處理200oC時已開始發生ZnO析晶現象，經熱處理400~600 oC可形成氧化鋅結晶。增加水濃度及酸性電解質濃度會增加薄膜微結構呈結團的現象。當熱處理溫度為400℃，無摻雜之薄膜其平均晶粒大小為(25±3 nm)，摻雜氯化鋁劑量為2.0at%具有較小平均晶粒(19±3 nm)；摻雜硝酸鋁劑量為1.0at%具有最小晶粒(15±3 nm)。乾燥後無摻雜及摻雜鋁劑量的膠體薄膜均具有介孔型的結構，其平均孔徑隨摻雜劑量的增加而變小，但隨溫度的增高其平均孔徑有變大趨勢。增加水及酸性電解質濃度會降低薄膜的透光性，經熱處理600℃時，未摻雜的薄膜可見光透光率為20%；摻雜氯化鋁劑量為3.0at%時，其透光率為40%；熱處理450℃後，摻雜硝酸鋁劑量為1.0at%的薄膜透光率為52%。經熱處理200~600℃後，薄膜的電阻率皆＞5.4×105Ωcm，經熱處理600℃時，摻雜硝酸鋁劑量為1.0at%，氣氛為空氣時，其電阻率為1.7×104Ωcm，當通入氮氣(N2)後其電阻率降低為1.0×102Ωcm。經熱處理400℃後，無摻雜的氧化鋅薄膜介電常數值為218~277；摻雜硝酸鋁劑量的增加，介電常數有減小的現象為214~261。

並列摘要

In this research, zinc oxide thin films were prepared via the solution chemistry. In addition to investigate the effects of water concentration and electrolytes on the structure, crystallity, microstructure and electro-optical properties of ZnO films, this research also studied the effects of doped Al on enhancing the conductivity and transmittance of zinc oxide films. In the experimental process, the precursors were zinc acetate and alcohol, and two aluminum compounds were used as dopants. It was observed that water concentration and electrolyte could remarkable affect the gelation rate of solution, the gelation rates increased with decreasing of water content but with increasing of acidic electrolyte amount. With different amount of water, electrolyte, and doped Al, the thermal activity and infrared spectra of films did not show significant difference. The doped-ZnO film (with 1at% Al) had a better crystallinity, but the crystallinity of film decreased with increasing the doped amount. The dried films began to form the ZnO crystalline phase after heat-treatment at 200℃.
Increasing the contents of water and electrolyte that would cause the film to form significant agglomeration. On heat-treatment at 400℃, the undoped-ZnO films had average grain size of 25±3nm, while the doped-ZnO films with 2.0at% AlCl3 and 1.0at% Al(NO3)3 had average grain sizes of 19±3nm and 15±3nm, respectively. Both the dried undoped and doped films possessed mesopore structures. Their pore sizes increased with decreasing dopant amount, but increased with firing temperatures.
The visible transmittance of films decreased with increasing the amounts of water and electrolyte. Upon firing at 600℃, the undoped-ZnO films had transmittance of 20% in visible light range, while the doped-ZnO films (with 3.0at% AlCl3) had transmittance of 40%. On heat-treatment at 450℃, the transparency of doped-ZnO films (with 1.0at% Al(NO3)3) were about 52%. After heat-treatment at 200-600℃ in air, the sheet resistivity of undoped-ZnO films were >5.4×105Ωcm. On heat-treatment at 600℃ in air, the sheet resistively of doped-ZnO films (with 1.0at% Al(NO3)3) were 1.7×104Ωcm, but decreased to 1.0×102Ωcm when N2 was used as atmosphere. The dielectric constant of undoped and doped ZnO films were 218~277 and 214~261 after heat-treatment at 400, respectively.

參考文獻

[21]汪建民，陶瓷技術手冊，全華科技股份有限公司，初版83年7月，p.241, p.242

[34]洪文進、許登貴、萬明安、郭書瑋、蘇昭瑾，ITO透明導電薄膜:從發展到應用到製備

[86]楊家銘，“奈米孔洞材料之物理吸脫附分析”，科儀新知，94.年6月，26卷，6期，

[1]J. H. Lee, B.O. Park, Thin Solid Films 426 (2003) 94-99.

[2]Y. Natume, H. Saksta, Thin Solid Films 372 (2000) 30-36.