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標題: 利用有機金屬化學氣相沉積製備加強型氧化鋅薄膜電晶體之特性研究
Characterization of enhancement-mode ZnO thin-film transistors using metalorganic chemical vapor deposition
作者: 沈俊宏
Shen, Jun-Hong
關鍵字: ZnO;氧化鋅;TFT;concentration;field effect mobility;MOCVD;薄膜電晶體;載子濃度;場效載子移動率;有機金屬化學氣相沉積法
出版社: 精密工程學系所
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我們利用有機金屬化學氣相沉積來沉積氧化鋅薄膜,並加以改善以達到可以利用在薄膜電晶體的水準。在本論文的第一部份先進行沉積溫度對氧化鋅結構之研究,實驗結果可以發現在300℃溫度下沉積可以使氧化鋅形成薄膜結構。一般利用有機金屬化學氣相沉積製備的氧化鋅薄膜載子濃度約為8×1018cm-3,並不足以達到可利用在電晶體通道層的水準,因此本論文第二部份是利用氧氣對氧化鋅薄膜進行高溫熱退火改善載子濃度之研究,結果可以發現氧化鋅薄膜因薄膜內部氧處理不足,導致載子濃度至多改善為9×1017cm-3,不甚理想。論文第三部份為改變退火方式為沉積過程逐步退火,結果可以發現在沉積過程中逐步退火在500℃的溫度下退火所得之氧化鋅薄膜,有效的大幅降低載子濃度為2.7×1015cm-3,此載子濃度足以當電晶體通道層之數量級。最後利用此一參數製作出薄膜電晶體,由電晶體的特性曲線表現,可得開關電流比為1.61×106,場效載子移動率為22 cm2/Vs。

In this thesis, ZnO thin films were prepared using a metalorganic chemical vapor deposition (MOCVD) system. In order to achieve ZnO with a lower carrier concentration for thin-film transistor (TFT) applications, the ZnO thin films are processed by various post-thermal treatment methods. First, the effects of deposition temperature of ZnO thin film were investigated. It was found that the ZnO with thin film structure could be obtained at a deposition temperature of 300℃. Generally, the carrier concentration of ZnO thin film prepared by MOCVD is 8×1018cm-3 and can not meet the requirement for TFTs. Thus, the ZnO thin films are treated with high temperature thermal annealing in oxygen ambient. However, the carrier concentration of ZnO can only be improved to 9×1017cm-3 and is not good enough due to insufficient of oxygen in ZnO. Finally, the carrier concentration of ZnO thin film was improved by using a multi-step annealing process. The carrier concentration of ZnO could be improved greatly to 2.7×1015cm-3 using the multi-step annealing at 500℃. This contributes the ZnO carrier concentration good enough to be used as channel layer in TFT. Finally, the ZnO TFT with Ion/Ioff ratio of 1.6×106 and field effect mobility of 22 cm2/Vs could be obtained under the optimized process conditions.
其他識別: U0005-0208201011012600
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