溶膠凝膠法製備P型及N型氧化鋅薄膜導電特性研究

使用無毒性溶劑及穩定劑以溶膠凝膠自旋塗佈法製作的氮銦共摻雜P型氧化鋅薄膜在室溫下可得到4.43歐姆公分的電阻率及1.36 × 1018每立方公分的載子濃度，利用鋁Kα光源X光光電子能譜偵測氮1s軌域及二次離子質譜儀縱深分析氮元素皆顯示氮已成功摻雜入氧化鋅。對鋁銦共摻雜的N型氧化鋅薄膜而言，第一道後退火環境的氧分壓對電性有明顯影響。將第一道後退火的環境由空氣改為氮氣僅犧牲少許可見光穿透率，但能大幅增加薄膜導電率。另外每一層薄膜塗佈之後都重複第一道後退火可減少有機物殘留的機會，減低雜質散射，有效提升電子遷移率。有機物殘留較少亦改善氧化鋅生長時的晶格品質，增進摻雜離子有效取代鋅離子的比率而提升電子濃度。以X光光電子能譜進一步分析摻雜前後的氧化鋅發現摻雜使吸附氧的情況變嚴重，大部分電子被薄膜表面或晶粒邊界中的氧分子捕捉而無法導電。第二道後退火對電子濃度的主要貢獻並非形成氧空缺或摻雜氫而是除去表面及晶粒邊界多餘的氧分子，我們發現無論是對本質氧化鋅或鋁銦共摻雜氧化鋅而言，氫氮混合氣環境比真空環境去除吸附氧效果更佳。然而當第二道後退火的溫度達攝氏500度時，氫氮混合氣和氧化鋅反應會過於劇烈而把氧化鋅薄膜蝕刻掉，因此存在最佳的第二道後退火溫度於攝氏400度。厚度200奈米N型氧化鋅薄膜的可見光平均穿透率均在百分之86到90之間，適於光電元件的應用。

關鍵字

溶膠凝膠；無毒性； P型氧化鋅；鋁銦共摻雜氧化鋅；去吸附氧

並列摘要

In-N co-doped p-type ZnO thin films have been demonstrated using a non-toxic sol-gel spin coating process. The resistivity of the p-type ZnO films is 4.43 Ω cm at room temperature. The X-ray photoelectron spectra of N 1s core level measured with an Al Kα photon line identify the existence of nitrogen in the p-type ZnO. The secondary ion mass spectrometry depth profile also confirms the nitrogen contents in the In-N co-doped films. For Al-In co-doped n-type ZnO films, varying the environment of the first post-annealing process from air to nitrogen brings about a great improvement in conductivity. In addition, repeating the first post-annealing step after every layer being deposited can improve the Hall mobility of ZnO films. The enhancement of mobility is attributed to the decrease of the impurity scattering caused by carbon related defects. Furthermore, Al-In co-doped ZnO films have been verified to absorb more excess oxygen than undoped ZnO films. The influence of the second post-annealing process on the carrier concentration is primarily attributed to oxygen desorption, not the increase of oxygen vacancies or hydrogen doping. Forming gas is a more effective annealing environment than vacuum ambient to activate the dopants.

並列關鍵字

sol-gel ； non-toxic ； p-type ZnO ； Al-In co-doped ZnO ； oxygen desorption

參考文獻

1. A. Tsukazaki, A. Ohtomo, T. Onuma, M. Ohtani, T. Makino, M. Sumiya, K. Ohtani, S. F. Chichibu, S. Fuke, Y. Segawa, H. Ohno, H. Koinuma and M. Kawasaki, Nature materials 4 (1), 42-46 (2004).

4. K. Ellmer and A. Klein, ZnO and Its Applications 1.2, page 4.

7. H. Hosono, Thin Solid Films 515 (15), 6000-6014 (2007).

9. V. A. Coleman and C. Jagadish, Basic Properties and Applications of ZnO 1.2.

10. K. Keis, E. Magnusson, H. Lindstrom, S.-E. Lindquist and A. Hagfeldt, Solar Energy Materials & Solar Cells 73, 51–58 ( 2002).

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溶膠凝膠法製備P型及N型氧化鋅薄膜導電特性研究

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