Study On The High Performance Organic Field Effect Transisitors Based On Interface Modification

With the development of the electronic information age, the oganic field effect transistor(OFET), which is an important part of the electron components, is making a huge progress. Because of its widely use in memories, electronic switches, RFID tags, electronic books, and so on, the performance of OFETs must be improved to meet the desperate need. After reviewing the structure, working principle and the characterization of the device, various modification methods have been taken to enhance the performance of OFETs.Firstly, the self assembly monolayer of octadecylsilane(OTS) and polymethylmethacrylate(PMMA) are used to modify the surface of silicon dioxide(SiO2). Both of them have make the mobility increase an order of magnitude. Besides, synthetic material with thiol groups is evaporated to modify the source and drain electrodes, which decreases the contact consistence between the electrodes and the semiconductor.Secondly, different annealing methods of modification layers are compared. Several materials are annealed in quenching and furnace ways separately. Generally, the devices fabricated by quenching reach higher electrical performance. In other words, quenching is better for the crystallization and growth of pentacene, which is verified by atomic force microscopy(AFM) images and X-ray diffraction(XRD), as well as the surface energy calculated from the contact angle of the dielectric surfaces.Finally, a bi-level polymer structure that consists of PMMA and cross-link Poly(4-vinylphenol)(PVP) is designed to effectively modify the SiO2. Apart from the high mobility(above 1 cm2/Vs), it is also stable in moisture. The best match of the desities is found after further optimizing, which is also confirmed by AFM, XRD and surface energy. The larger grain size and higher crystallinity of pentacene can be realized on the dielectrics with lower surface energy, resulting in the enhanced stability and performance of the device.