在未來顯示器尺寸與解析度不斷提高的趨勢下，氧化鋅相關薄膜電晶體是目前最具潛力取代非晶矽與低溫多晶矽為主的電晶體，主要原因在於氧化鋅電晶體具有較高的載子遷移率(>10 cm2/ V?s)、對可見光較不敏感、以及可與目前薄膜電晶體製程上的匹配性。 為了製備高載子遷移率的氧化鋅薄膜，文中首先探討氧化鋅與鎵摻雜氧化鋅在氧氣或氮氣中以不同熱退火溫度處理的結果，並以其結構、電性與光學上的變化，探討氧化鋅中缺陷的產生與抑制，最終歸納出一個最佳的熱退火溫度與環境。 利用上述成果，我們利用該氧化鋅製作一金屬-絕緣層-半導體電晶體(MIS-FET)，同時討論不同絕緣層結構之電晶體的元件特性。最佳的元件特性其最大開啟電流密度(IOn)可達到33 mA/mm，同時維持開關比(IOn/IOff ratio)達到108，次臨界斜率(sub-threshold slope, SS)為150mV/decade，經過計算，等效的通道載子遷移率可達35.2 cm2/ V?s，元件在關閉的情況下，崩潰電壓可達125V。元件特性顯示，經過熱退火後的氧化鋅電晶體具有應用的潛力。 In the future, when the size and resolution of displays continuously increase, ZnO-based thin film transistor (TFT) is one of the potential replacement for amorphous-Si and low temperature poly-Si TFTs based on its higher mobility (>10 cm2/ V?s), less light sensitive and compatible fabrication process. To achieve a high mobility ZnO film, the properties of annealed ZnO and Ga-doped ZnO in oxygen or nitrogen ambient were investigated. Structural, electrical and optical properties were summarized to explain the generation-annihilation of defects. In the end, an optimal annealing temperature and environment were proposed. According to the results mentioned above, a ZnO-based metal-insulator-semiconductor TFT was fabricated. Besides, different insulators were also introduced in these TFTs. A high On-state current density of 33 mA/mm and IOn/IOff ratio over 108 were simultaneously obtained. The sub-threshold swing was 150mV/decade. The effective channel mobility is near 35.2 cm2/ V?s extracted from the formula. These results indicate that annealed ZnO materials have promising characteristics to apply to TFTs.
