【作者】 吴仁磊；

【导师】 程晓曼；

【作者基本信息】 天津理工大学 ， 凝聚态物理， 2010， 硕士

【摘要】 有机场效应管(OFET)以其低成本且可大批量生产、制作工艺简单、机械柔性、重量轻、可大面积化及化学稳定性等优点,使得它在开关、智能卡、传感器、环形振荡器、平板显示、鉴别标签及集成电路等领域具有潜力的应用,引起了极大的关注。经过二十几年的发展,OFET已经取得了巨大的进展,成为重要的电子器件之一。在OFET中,双极性OFET由于其适用于有机集成电路(ICs)中的互补电路和实现场效应与光发射集成于一体的有机光发射场效应晶体管,成为近几年的研究目标。因此功能化的OFET逐渐提上日程。本论文首先综述了有机电子学器件中OFET近20年的发展历史、应用及研究意义,讨论了OFET目前研究中存在的问题与发展趋势。总结了OFET器件的基本结构及有机半导体材料、栅绝缘层材料、电极材料等OFET常用的基本材料。阐述了OFET的工作原理及其界面接触理论,然后总结了提高OFET器件性能的一些方法。针对目前OFET的研究现状和存在的一些问题,以OFET为研究对象,从选材入手,制备了基于聚合物栅绝缘层的并五苯OFET、基于并五苯与C60异质结的双极性OFET和基于铝电极单一并五苯有源层的类双极性OFET等器件。本论文的主要研究工作有以下几个方面:(1)以聚合物材料聚甲基丙烯酸甲酯(PMMA)和聚酰亚胺(Polyimide)分别作为栅绝缘层,高迁移率并五苯为有源层材料,低成本的铝为源漏电极,ITO作为栅电极,制备了OFET器件,器件具有典型的P-沟道传输特性。另外,制备了基于不同厚度的PMMA栅绝缘层的并五苯OFET器件。研究了绝缘层厚度对器件性能的影响,并分析了半导体与绝缘层界面偶极子效应对器件性能的影响。(2)制备了基于C60与并五苯异质结的双极性OFET,其中C60作为N-沟道材料,高迁移率的并五苯作为P-沟道材料和C60的保护层,PMMA作为栅绝缘层,低成本的铝作为源漏电极。空穴和电子迁移率分别达到1.0877×10-1cm2/V·s和1.6186×10-2cm2/V·s。双极性OFET成为功能化OFET的重要组成部分。(3)制备了基于单一并五苯有源层的类双极性OFET。通过一些理论分析证明了该实验方案的可行性。在硅衬底的SiO2绝缘层上旋涂表面能与并五苯相匹配的无氢氧基的PMMA作为栅绝缘层的修饰层,有助于并五苯晶粒的生长,降低了电子在其界面的陷阱,选择功函数位于并五苯LUMO与HOMO能级之间的Al作为源漏电极有利于实现双极性电荷传输,从而为低成本功能化OFET奠定了基础。更多还原

【Abstract】 Organic field effect transistors(OFET)have attracted great attention for potential application in basic switching elements, smart cards, sensing devices, ring-oscillators, ?at panel displays, identification tags and integrated circuit, due to their low cost processing, facile procedure, mechanical ?exibility, lightweight, large-area and chemical stability. By the development of over the last two decades, considerable improvements have been achieved. OFET becomes one of the most important electronical devices. Among the OFET devices, ambipolar OFET have become research targets since they are potentially available for complementary circuits in organic integrated circuits and organic light-emitting field effect transistors, which could achieve the function of field-effect and light emitting. Thus functional OFET are put on the agenda.Firstly, the evolution history in the latest two decades, application and research significance of OFET was summarized. The existing problem and developmental trends of OFET were discussed. Secondly, the basic structure and commonly used materials, such as organic semiconductor material, gate insulating layer material and electrode material of OFET were summarized. The principle and interface contact theory of OFET was studied in detail. Then some methods of improving performance of OFET were described.According to the research status and some existing issues of OFET, taking OFET as the object of study, pentacene OFET based on polymer gate insulator and ambipolar OFET based on a pentacene/C60 heterojunction were fabricated, respectively. Finally, quasi-ambipolar OFET based on aluminum electrode and single pentacene active layer were fabricated.The major work is summarized as follows:(1) Pentacene OFET based on PMMA and Polyimide gate dielectrics have been fabricated on ITO-coated glass substrate using ITO as gate electrode, respectively. Aluminum is using as source and drain electrodes. The devices exhibit typical P-channel characteristics. In addition, pentacene-based OFET using various thickness PMMA gate dielectrics are fabricated. The interface properties between gate insulator and pentacene active layer and the effects of the insulator thickness on the performance of the devices have been investigated, respectively.(2) Ambipolar OFET with a heterostructure of pentacene/C60 have been fabricated, in which the C60 layer functions as an n-type channel, while the pentacene layer functions as both a p-type channel and a sealing capsule for the C60 layer. PMMA is employed as gate insulating layer and low-cost Al is used as S/D electrodes. The ambipolar OFET, operating in an ambient atmosphere, exhibit a hole mobility of 1.0877×10-1cm2/V·s in the p-type operation and an electron mobility of 1.6186×10-2cm2/V·s in the n-type operation. Ambipolar OFET is the important part of functional OFET. (3) Single pentacene active layer-based quasi-ambipolar OFET have been fabricated. Firstly, the feasibility of the experimental program is confirmed by theoretical analysis. A thin PMMA-modified layer is spin-coated on SiO2 gate dielectric. The presence of ambipolar behavior is attributed to the relatively small surface energy on the PMMA-modified SiO2 gate dielectric as compared to that on the bare SiO2 surface. Thus the enhanced grain growth of pentacene takes place and hence reduce grain boundary density. Al is used as S/D electrodes, which possess a suitable work function to balance the hole and electron injection into the highest occupied and the lowest unoccupied molecular orbitals of pentacene, which lay the foundation for functional OFET.更多还原