單晶有機場效電晶體的製備

數十年來，有機場效電晶體的蓬勃發展，使之成為一熱門之研究主題。隨著電荷躍遷模式的理論備完善後，我們很清楚地了解分子堆疊的秩序性將會大大影響到元件的電荷遷移率，所以有機半導體之單晶結構便吸引了眾多學者的目光。除了可從中觀察到半導體材料本身之電性，亦可藉此探討場效電晶體的其它元件特性。在本篇研究中，我們利用矽晶圓為基板，並利用物理氣象傳輸法來生成單晶結構；相較於其它長晶方法，可以大大縮減耗費的時間。可惜除了 Rubrene 以外，我們無法獲得其它的化合物單晶。而後再利用蒸氣沉積法將 perfluorotriethoxysilane ﹙FTS﹚覆蓋於單晶上，除了達到保護單晶之效果，另一主要用途在於提高單晶與下方電極之接觸。透過偏光顯微鏡確認物理氣象傳輸法成品之單晶，並透過電性量測系統來觀察各種不同元件結構之個別效率。而最後結果發現只有下接觸式之元件結構才擁有場效電晶體之特性，雖然所量測到的電洞遷移率只有4.4 × 10-2 cm2 V-1 s-1；而且電流開關比也非常小，與電性圖中所觀察到明顯的漏電流現象相呼應。因此如何改善元件結構是後續重要的課題之一。

關鍵字

單晶；有機場效電晶體； Rubrene ；物理氣象傳輸法； FTS

並列摘要

Organic field-effect transistors have been rapidly developed in the past decades. According to the charge-transport mode, molecular packing will effect the performance of mobility. So, the organic single crystal and their OFETs can be useful for the investigation of the intrinsic nature of the electrical properties and of the device characteristics. In this work, we use Si as substrate and SiO2 as the insulator. Single crystals have been growth using the physical vapor transport method to decrees the time scale of crystallization. Then, FTS films by vapor deposition protect the single crystal on the top of the device. For one thing, We try many kinds of the device structures and the bottom-contact device is the only one could be measured. The highest hole mobility is 4.4 × 10-2 cm2/Vs. But the on/off ratio is so disappointing. It reveals a huge leakage current so that we have to change the protecting materials or device. So, this is our chief objective to improve the performance by finding the ideal device structures.