石墨烯和二硫化钼的CVD法制备及其光学性能的研究

发布时间：2018-06-13 23:03

本文选题：石墨烯 + 二硫化钼　；参考：《北京交通大学》2016年博士论文

【摘要】：二维材料是一类新兴的纳米材料,由于其独特的结构和优异的性能引起了科学界的广泛关注。二维材料被认为在高频电学器件、透明电极、储能、生物医药以及复合材料等领域有巨大的应用潜力。而二维材料的大规模应用离不开大面积、高质量的可控制备。本论文主要围绕大尺寸、单晶石墨烯和二硫化钼的可控制备这一问题,以化学气相沉积法为手段,制备了石墨烯、二硫化钼以及二硫化钼／石墨烯异质结。系统研究了制备过程中,生长工艺以及生长参数对二维材料尺寸、层厚和结晶质量的影响,以及石墨烯的硫化、MoS2/石墨烯异质结的光致发光性能,并提出了利用光学显微镜得到的对比度数据得知二维材料的尺寸、层数等信息的方法。具体研究内容如下：(1)研究了CVD法制备石墨烯过程中,生长工艺以及生长参数对所制备的石墨烯尺寸及厚度的影响,对所得的石墨烯样品进行了形貌及物性表征。探究了CVD制备的生长工艺和生长参数：衬底的清洗、退火和温度；气源浓度对石墨烯生长的影响,包括甲烷和氢气的浓度。实验发现气源浓度对石墨烯的层厚影响较为关键,通过调控生长参数,在铜箔表面得到了面积较大的双层石墨烯,并对其生长机理进行了分析和解释。(2)研究了CVD法制备单层MoS2以及MoS2/石墨烯异质结。研究了生长温度、生长时间以及反应源的浓度对单层MoS2生长的影响,得到了单晶尺寸在40μm以上的单层MoS2薄膜。在石墨烯表面采用CVD法生长出了MoS2/石墨烯异质结,通过各种表征手段分析了二硫化钼在石墨烯表面的生长模式、表面形貌、层厚等。研究了石墨烯受到硫化对其晶格结构以及缺陷的影响。实验还发现石墨烯可以改变二硫化钼的能带结构,同时对二硫化钼的光致发光具有猝灭作用。(3)根据菲涅尔原理,采用光学薄膜等效的方法,计算了二维材料样品在不同厚度的二氧化硅／硅衬底上,不同的入射光下,其相对于衬底的对比度变化。并利用CVD制备的MoS2和MoS2/石墨烯异质结对计算结果进行了验证。根据计算结果,我们可以在不需要使用原子力显微镜和拉曼光谱仪的情况下,采用光学显微镜精确的表征二维材料的层数。这为二维材料的层厚表征提供了一种简便、有效的方法。通过计算不同堆叠形式的TaS2在衬底上的对比度,还发现该方法可以用来判断二维材料的堆叠形式。涉及的二维材料主要包括石墨烯、六方氮化硼、2H-MoS2、2H-MoSe2、2H-MoTe2、2H-WSe2、2H-NbSe2、3R-WS2、TaS2以及MoS2/石墨烯异质结等。
[Abstract]:Two-dimensional materials are a new kind of nanomaterials, which have attracted wide attention of the scientific community because of their unique structure and excellent properties. Two-dimensional materials are widely used in high frequency electrical devices, transparent electrodes, energy storage, biomedicine and composite materials. The large-scale application of two-dimensional materials can not be separated from large-area, high-quality controllable preparation. In this thesis, graphene, molybdenum disulfide and molybdenum disulfide heterojunction were prepared by chemical vapor deposition (CVD), focusing on the controllable preparation of single crystal graphene and molybdenum disulfide. The effects of growth process and growth parameters on the size, layer thickness and crystallization quality of two-dimensional materials and the photoluminescence properties of MoS _ 2 / graphene heterojunction of graphene were systematically studied. A method is proposed to obtain the size and the number of layers of the two-dimensional material by using the contrast data obtained from the optical microscope. The effects of growth process and growth parameters on the size and thickness of graphene were studied. The morphologies and physical properties of the graphene samples were characterized. The growth process and growth parameters of CVD were investigated, including substrate cleaning, annealing and temperature, and the effect of gas concentration on the growth of graphene, including methane and hydrogen. It was found that the concentration of gas source had a key effect on the thickness of graphene layer. By adjusting the growth parameters, a large area of bilayer graphene was obtained on the surface of copper foil. The growth mechanism of MoS2 monolayer and MoS2 / graphene heterojunction were investigated by CVD. The effects of growth temperature, growth time and concentration of reaction source on the growth of MoS2 monolayer were studied. The single layer MoS2 thin films with single crystal size above 40 渭 m were obtained. MoS2 / graphene heterojunction was grown on graphene surface by CVD. The growth pattern, surface morphology and layer thickness of molybdenum disulfide on graphene surface were analyzed by various characterization methods. The effects of sulfidation on the lattice structure and defects of graphene were investigated. It was also found that graphene can change the energy band structure of molybdenum disulfide, and the photoluminescence of molybdenum disulfide can be quenched. The contrast changes of two-dimensional samples with different thickness of silicon dioxide / silicon substrate with different incident light compared to the substrate have been calculated. The calculation results of MoS2 and MoS2 / graphene heterojunction prepared by CVD were verified. According to the calculation results, we can use optical microscope to accurately characterize the number of layers of two-dimensional materials without using atomic force microscope and Raman spectrometer. This provides a simple and effective method for the characterization of the thickness of two-dimensional materials. By calculating the contrast of different stacked TaS2 on the substrate, it is also found that this method can be used to judge the stacking form of two-dimensional materials. The two dimensional materials mainly include graphene, hexagonal boron nitride 2H-MoS _ 2, 2H-MoS _ 2o _ 2H-MoE _ 2e _ 2H _ W _ (se _ 2) ~ (2H-NbSe_ 2) ~ (3R-WS _ 2) TaS2, MoS _ 2 / graphene heterojunction, etc.
【学位授予单位】：北京交通大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TQ127.11;TQ136.12

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