CVD法制备石墨烯及其在有机薄膜晶体管中的应用

发布时间：2018-04-29 13:09

本文选题：石墨烯 + 化学气相沉积　；参考：《合肥工业大学》2015年硕士论文

【摘要】：石墨烯是一种由碳原子构成的单原子层二维薄膜材料。特别地,石墨烯因具有超高的载流子迁移率、合适的功函数、超高的透明度和优异的化学稳定性等因素,使其在显示器件、电子器件、光电器件等领域具有广阔的应用前景。目前,制备高质量大面积的石墨烯仍是石墨烯研究的重点。本文采用化学气相沉积(CVD)法,在铜箔上面生长高质量单层的石墨烯,将其转移到SiO2/Si和PET衬底上。用layer-by-layer (LBL)的方法获得了具有不同表面性质的多层石墨烯,并制备了基于石墨烯电极的场效应薄膜晶体管(OTFT)。主要的研究内容和工作如下：(1)对单层石墨烯的CVD生长条件进行了优化,成功制备出高质量的石墨烯。实验结果表明,铜箔经过机械抛光和高温退火处理后,表面变得整洁、晶粒变大,有利于形成高质量的石墨烯；甲烷的浓度决定着石墨烯的层数；氢气不仅可以促进甲烷的分解又可以对石墨烯起到刻蚀效果,能帮助提升石墨烯的质量。结合上述的分析和实验我们确定了适于我们设备的生长参数。(2)在石墨烯的转移实验中,我们研究了衬底的处理以及石墨烯的预处理对转移结果的影响,发现紫外臭氧处理的衬底能增加石墨烯与衬底的粘附力,有利于完整石墨烯膜的转移；用氧等离子体体处理铜箔背面能够获得洁净度高的石墨烯。通过紫外光刻的方法制备了石墨烯电极。(3)成功制备了基于石墨烯电极的OTFTs器件,并与金电极的OTFTs器件作对比,单层石墨烯器件的最大迁移率达到0.56 cm2V-1s-1,要比金电极的OTFT大很多,证明我们制备的单层石墨烯在微电子领域具有很好的应用价值。(4)研究了电极／有机半导体界面对基于石墨烯做电极的OTFTs器件性能的影响,通过LBL的方法制备了不同表面性质的多层石墨烯。实验发现,随着层数的增加石墨烯的表面粗糙度、导电性、功函数也随之增加。尽管多层石墨烯的导电性和功函数都有利于器件性能的提高,但是粗糙的界面扰乱了并五苯的生长,破坏了半导体薄膜在石墨烯电极／有机半导体界面处的连续性,不利于电荷在界面处的注入与传输。因此,界面粗糙度越大OTFTs器件性能就越差。石墨烯的粗糙度成为了决定石墨烯器件性能的主要因素。因此,在今后的实验中获得平坦、均一的石墨烯是非常必要的。
[Abstract]:Graphene is a two-dimensional thin film material composed of carbon atoms. In particular, graphene has a broad application prospect in display devices, electronic devices, optoelectronic devices and other fields because of its ultra-high carrier mobility, appropriate work function, ultra-high transparency and excellent chemical stability. At present, the preparation of high-quality and large-area graphene is still the focus of graphene research. High quality graphene monolayers were grown on copper foil by chemical vapor deposition (CVD) method and transferred to SiO2/Si and PET substrates. Multilayer graphene with different surface properties was obtained by layer-by-layer / LBL method, and a field effect thin film transistor (FET) based on graphene electrode was prepared. The main research contents and work are as follows: (1) the CVD growth conditions of graphene monolayer were optimized and high quality graphene was successfully prepared. The experimental results show that the copper foil after mechanical polishing and high temperature annealing makes the surface clean and the grain size bigger which is conducive to the formation of high quality graphene and the concentration of methane determines the number of layers of graphene. Hydrogen can not only promote the decomposition of methane, but also etch graphene and improve the quality of graphene. Based on the above analysis and experiments, we have determined the growth parameters suitable for our equipment. In the graphene transfer experiment, we have studied the effect of substrate treatment and the pretreatment of graphene on the transfer results. It is found that the substrate treated by ultraviolet ozone can increase the adhesion of graphene to the substrate, which is beneficial to the transfer of the complete graphene film, and the high cleanness graphene can be obtained by treating the back of copper foil with oxygen plasma. OTFTs devices based on graphene electrodes were successfully fabricated by UV lithography. Compared with OTFTs devices with gold electrodes, the maximum mobility of monolayer graphene devices was 0.56 cm2V-1s-1, which was much larger than that of gold electrodes. It is proved that our monolayer graphene has good application value in the field of microelectronics. The effect of electrode / organic semiconductor interface on the performance of OTFTs devices based on graphene electrode has been studied. Multilayer graphene with different surface properties was prepared by LBL. It is found that the surface roughness, conductivity and work function of graphene increase with the increase of the number of layers. Although the electrical conductivity and work function of multilayer graphene are beneficial to the improvement of device performance, the rough interface disturbs the growth of pentabenzene and destroys the continuity of semiconductor film at the graphene electrode / organic semiconductor interface. It is unfavorable to the injection and transmission of charge at the interface. Therefore, the higher the interface roughness, the worse the performance of OTFTs devices. The roughness of graphene has become the main factor to determine the performance of graphene devices. Therefore, it is necessary to obtain flat and uniform graphene in future experiments.
【学位授予单位】：合肥工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN304.055;TN321.5

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