The Research On Application Of Graphene In Field Effect Transistors

From the beginning to now, microelectronics is developing accord to the Moore Law. But with the critical dimension of devices decreasing, microelectronics industry is facing with a big challenge, researchers in all over the world are working hard to find a way to overcome this problem. With the development of all kinds of technology, a new technique, carbon-based microelectronic technology, emerged and could be the core of next generation of electronic technique. One of these carbon-based materials is graphene. Graphene is a rapidly rising star on the horizon of materials science and condensed-matter physics. This strictly two-dimensional material exhibits exceptionally high crystal and electronic quality, the unprecedented high carrier mobility, high thermal and electrical conductivity of gtraphene make it a promising material for nanoelectronic devices, and has already revealed potential applications in post-complementary metal oxide semiconductor electronics.So far, there are several methods to fabricate graphene, such as mechanical exfoliation of graphite on SiO2/Si, epitaxial growth of graphene on metal substrates and oxidation of graphite. But all these kinds of methods can not meet the demand of practical applications, and don’t take full advantage of graphene. Considering the high conductivity, one atom thick structure and high compatibility with organic semiconductors, graphene is a promising electrodes material for organic devices. Until now, most semiconductor mirco and nanodevices are top-contact structures, the process of device fabrication is placing organic crystals firstly, then depositing metal electrodes on them. Due to the fragility of organic crystals, traditional micro and nanotechnology can not be used, and top-contact electrodes usually are deposited by shadow mask evaporation in vacuum environment. Thermal radiation in fabrication process would influence the performance of organic devices. Another type of organic devices is bottom contact structure, the bottom contact electrodes are deposited firstly, then organic crystal is placed on top of the electrodes. Because of no restriction from organic crystal, the electrodes can be fabricated by micro-fabrication methods, such as photolithography. But the main disadvantage of bottom contact structure is the thickness of electrodes, the steps between electrode and insulating layer would influence the combination of organic crystal and insulating layer, lead to decrease of device performance, even out of performance. Monolayer graphene, with high crystallographic quality, high electrical conductivity, high compatibility with organic semiconductors, is only0.4nm, if it is used as bottom contact electrodes material, the problem induced by thick metal electrodes would be solved.In this paper, the preparation and characterization of graphene are introduced, and we report a simple and convenient way to fabricate graphene microscaled-gap S/D electrodes by a novel micro-wire mask method, and demonstrated such graphene can be used as suitable electrodes for low-cost organic electronics. The graphene electrodes exhibit good charge carrier injection characteristics and efficient interface contact with organic semiconductor. The copper phthalocyanine (CuPc) thin film-based OFET with bottom-contact geometry show a high mobility of0.053cm2/Vs, and an on/off ratios larger than104. Even though the depositing condition of CuPc films is not optimized, the performance of our devices still compare favourably with the reported CuPc devices with bottom-contacted gold electrodes. Research results demonstrate that graphene is a good electrode material, and could be a commonly used material to fabricate high performance inorganic and organic devices.