軟性電子元件具可撓曲結構，低溫製程，低成本與易於攜帶等特點，因此成為目前相當熱門的研究主題。而有機薄膜電晶體（organic thin-film transistor；簡稱OTFT）可用以驅動液晶（liquid crystal）或有機發光二極體（organic light emitting diodes；簡稱OLED），作為主動式平面顯示器(active matrix flat panel display)的開關，或未來電子紙（electronic paper)內部的重要元件。本論文將以非接觸式配向技術改善有機分子排列，並以此方法應用於OTFT 元件中，藉以改善元件的製程與特性。此外，使用臨場拉曼光譜量測(in-situ microRaman)分析有機薄膜結構與載子傳輸的關聯。最後藉由控制有機介電層的表面極性與表面能，達成具有較高載子遷移率的有機電晶體元件。本論文首先回顧文獻上有關有機半導體薄膜特性與其載子傳輸的理論，如載子的躍遷模型、捕捉態、偏極子等，及有機薄膜電晶體操作的相關原理。同時也簡介一般非接觸式配向方法以及相關量測技術。其次分別討論光配向 (photoalignment) 與離子束配向(Ion-beam processed)處理過之有機薄膜特性，其中離子束配向有機薄膜方法為本實驗室首先提出的技術。應用此兩方法於OTFT 元件中，以提升元件操作特性，如載子遷移率、起使電壓、元件開關比、電流異向性等重要操作參數。再來我們使用拉曼散射，分析OTFT 元件在操作時的有機薄膜內部的聲子訊號，發現不同方向電場偏壓下，將造成薄膜結構的相變，藉此以瞭解有機分子在電場下交互作用的影響，可解釋OTFT 元件電性穩定性與有機薄膜排列結構的關係。最後，研究介電層表面特性對元件的關係，發現介電層表面能對OTFT 元件特性有高度相關性，非極性及適當的表面能值，可幫助有機薄膜具有最佳的晶格品質，此將有助於內部載子的傳輸。

Organic thin-film transistors (OTFTs) can be a competitive candidate for existing or novel thin film transistor applications that require structural flexibility, low temperature processing, and especially low cost. Such
applications include the switching devices of active matrix for flat panel displays based on liquid crystal pixels, organic light emitting diodes, or electronic papers. In this thesis, we achieved non-contact alignmenttechnologies including photoalignment and ion-beam alignment in OTFTs. We also investigated the relations of organic semiconductor films structure and it’s carrier transport by in-situ microRaman spectroscopy and tried to improve the carriers mobility by the modifications of dielectric layer surface polarity and energy. First, we review the theories of carriers transport and the characteristics of an organic thin film, such as carriers hopping, trap states, polarons, and the OTFTs’ operation. We also described alignment methods and measurements for OTFTs. Secondly, we discussed and compared the physical characteristics and performance, which contains the field-effect mobility, threshold voltage, and on/off ratio of OTFTs with the photoalignment method and ion-beam processed method. In addition we observed the lattice phonon of pentacene molecules under different conditions that devices operated at various source-drain and gate voltages. Phase transition of pentacene film of OTFTs were induced by the applied external electrical field parallel to the cannel between the source and drain electrodes. From the analysis, we can investigate the coupling of adjacent molecules under external electrical field and find it will play an important role for carriers transport.In last, we studied the thin-film structure and carrier mobility affected by the surface free energy and polarity of the gate dielectrics strongly. We find that a controllable surface energy of dielectrics can effectively avoid structural dislocation and reduce the carriers scattering from film defects. Lower free energy and non-polarity of the dielectric is good for the growth of a pentacene thin film and its performance.

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