具空氣穩定性的雙極性有機薄膜電晶體

Abstract

本論文探討利用pentacene和PTCDI-C8兩種有機半導體材料為主動層，製作成雙層結構的雙極性有機薄膜電晶體，由於n型電性容易受水氣的影響，成長在二氧化矽基板上的元件只能在惰氣環境中呈現雙極性的特性，但是經由有機高分子材料修飾二氧化矽基板後，卻能在大氣環境下操作在正負偏壓，在40天後仍有雙極性電晶體的電性。我們推測出絕緣層介面上的氫氧根為空氣中n型電性不佳的主因。此外，藉著改變pentacene和PTCDI-C8的蒸鍍順序可以得到較佳的結構，並調變兩者的厚度，使元件擁有最匹配的p與n型電流，且經由電容特性曲線分析，發現與傳統單一極性電晶體不同，在正負閘極偏壓都會累積載子。最後，我們成功將兩顆相同條件的雙極性有機薄膜電晶體製作成反相器，能夠操作在第一和第三象限，可大量簡化複雜的電路設計。

Air-stable ambipolar organic thin-film transistors (OTFT) based on the double active layer of pentacene / PTCDI-C8 have been made. Because the n-channel performance is easily affected by water and oxygen, the device on SiO2 can only exhibited ambipolar OTFT properties in inert conditions. However, after modification of the surface of the SiO2 by polymers, the device exhibited ambipolar characteristics under ambient conditions. The ambipolar OTFT still work after 40 days in the air. According to the experiments, we infer that hydroxyl groups on dielectric have a profound effect on n-channel properties. Furthermore, from the capacitance-voltage measurements, we observed that ambipolar OTFT accumulated holes and electrons under negative and positive voltages respectively. Finally, a CMOS-like inverter has been constructed by using two identical ambipolar transistors. The inverter could operate in both the first and third quadrants, thereby simplifing the IC design.