Research Of Organic Field-effect Transistors Based On Pentacene

Organic field-effect transistor(OFET)is a kind of novel electronic device,and is also a kind of active device using electric field to contral the electric conductivity of solid materials.OFET is attracting more and more interests because of its series of advantages over Inorganic field-effect transistor,such as low-cost,flexility and large area processing.OFET has already become one of the most important organic electronic devices throngh more than ten years of development.This thesis reviews the research background,development history,applied domain and research hotsport of organic field-effect transistor.The structure and organic semiconductor material of OFET are summarized.We introduce electric conductivity types of organic semiconductor material,energy band relationship between metal electrode and organic semiconductor,carrier transmission mechanism and metal/organic semiconductor contact theory of organic semiconductor at present. The basic work principle of OFET is discussed from the basic wotking model and I-V equation.We also discuss carrier field-effect mobility physical signification and calculational methods of OFET.The thesis focuses on pentacene OFET.The organic field effect transistors had been fabricated using the pentacene by vacuum evaporation as the active layer,the polyimide by spin coating and SiO₂ by thermally grown as insulator layer,and aluminum and aurum by vacuum evaporation as gate,source and drain electrodes respectively,using the atomic force microscopic(AFM)image analyzed the polyimide layer and pentacene thin film surface morphologies.We got the mobility 0.079cm²/V.s for the polyimide device,0.073cm²/V.s and 0.42cm²/V.s for the SiO₂ device,and found that the substrate temperature effect evaporation velocity and mobility,the pentacene film have a best substrate temperature and thickness.Finally the author summarized the thesis work,and discussed development direction and application foreground.