背通道效應對雙極性有機薄膜電晶體特性的影響

Abstract

本研究中利用不同特性的材料作為背通道層，製作成雙極性有機薄膜電晶體，研究背通道層中氫氧官能基對有機薄膜電晶體特性的影響。以不同材料作為背通道層材料的元件出現了明顯的特性變化，包含載子遷移率、電流開關比的提升，與截止電壓的飄移。為了確認此現象是否是源於背通道層中的氫氧官能基所產生的電子捕捉效應，我們進一步利用不同交聯程度的聚(4-乙烯基苯酚)作為背通道層材料來定性分析；同時也比較在不同主動層厚度下，以不同背通道層材料製成的有機薄膜電晶體特性的差異。由實驗結果可推論材料中的氫氧官能基不只在主動層與閘極介電層的交界面對有機薄膜電晶體的特性有所影響，類似現象同時也出現在主動層與背通道層的交界面上。最後我們嘗試以聚乙烯醇肉桂酸酯作為背通道材料層的雙極性有機薄膜電晶體來製作反向器，完成後的元件增益能達到-37.7、雜訊邊際〖"NM" 〗_"L" "=5.1 V" 、〖"NM" 〗_"H" "=10.3 V" 。

In this thesis, we discuss the back-channel effects on the characteristics of ambipolar organic thin-film transistors(OTFTs), we fabricated bottom-contact OTFTs with various materials as the back-channel layers, including PMMA, PVCN, PVP, HMDS and Pristine Glass. Variations in the characteristics, including carrier mobility, on-off ratio and the shift of threshold voltage, appeared in the devices with different back-channel layer materials. In order to confirm whether this phenomenon came from the electron trapping effect produced by the hydroxyl groups in back-channels, we added different amount of cross-linking agents in the PVP dielectrics, and compared the characteristics of OTFT devices with different thickness of the active layers. As a result, we found that not only the hydroxyl groups in dielectric layers affected the characteristics of OTFTs, those in the back-channel layers also led to similar phenomenon. On the other hand, we used the ambipolar OTFTs in this work to construct CMOS-like inverters, and achieved a maximum inverter Gain of -37.7, and noise margin of 〖"NM" 〗_"L" "=5.1 V" 、〖"NM" 〗_"H" "=10.3 V" .