有機-高介電複層薄膜電晶體

Abstract

平面顯示器於最近未來將進步到可折曲式的電子紙或電子書。此類產品特點是由高效 能有機薄膜電晶體構成驅動線路，製作在軟性塑膠版或薄金屬版上。有機薄膜電晶體中有 機半導體材料將取代矽晶半導體。將使製程更簡化、成本低廉，顯示器將有重量輕、耐摔 與耐衝擊等特性 目前有機半導體研究以p-型材質較為成熟。例如pentacene，其載子遷移率可達1-2 cm2V-1s-1，足以和非晶矽半導體相比。另一方面，投入研究n-型有機半導體則遠為不足， 性質一直未能提升。因為業界常採用節能的n-p 型互補示電晶體。現階段已有必要開發高 效能的n-型元件。 依據本實驗室以前研發薄膜電晶體的經驗，本計畫將以兩年時間開發高性能n-型有機 薄膜電晶體。其中第一年工作包含新穎n-型有機半導體材料的合成與鑑定，成長有機半導 體單晶及x-ray 繞射分析有機分子堆疊特性，有機電晶體元件製作及電性量測，第二年工作 包含選用不同功函數之金屬電極，配合第一年合成之有機半導體，做成「下接觸式電極」 元件，以減少金屬/有機接觸電阻。另外以濺鍍方式製作高介電氧化物取代二氧化矽作為閘 極絕緣層。然後將有機半導體化合物成長於高介電膜上，研製成n-型有機-高介電複層薄膜 電晶體，具有高載子遷移率(~ 0.1cm2/Vs)及高電流開關比(>106)。

Flexible e-paper and e-book would be the trend of flat panel display in the near future. The driving circuits of those products are made of organic thin-film transistors (OTFT) and set on soft plastic or thin metallic board. Organic semiconductor material would replace silicon semiconductor in the OTFT, which would lead to simplified processing and low cost. Also, the light-weight display can survive through accidental smash or impact. The study on the p-type organic semiconductors is relatively mature. Pentacene is an example with high charge carrier mobility of 1-2 cm2V-1s-1, comparable to amorphous silicon. On the other hand, n-type organic semiconductors have been far less studied and their relevant properties remained unsatisfied. It is time to develop high performance n-type OTFT to meet the industrial demand on the energy-saving n-p complimentary circuits. Based on the previous research experiences on the thin film transistors in our lab, a two-year research plane is proposed to develop high-performance n-type OTFT. The efforts in the first year includes: synthesization and characterization of new n-type organic semiconductors, growth of the new n-type organic semiconductors in single -crystal and analysis by x-ray diffraction on the stacking of organic molecules in the crystal, fabrication of OTFT and associated measurements. The efforts in the second year includes: fabrication of bottom-contact OTFT with low metal/organic contact resistance by selecting metallic electrodes with suitable work function matching with the synthesized organic semiconductors, fabrication of n-type organic-high dielectric composite layer TFT, in which the SiO2 gate insulator was replaced by high-dielectric oxide where the organic semiconductor was grown on. The performance of the d would have a charge carrier mobility ~ 0.1cm2/Vs and current on/off ratio more than 106.