石墨烯基和氧化锌基多层薄膜的气相沉积法制备及性能研究

发布时间：2019-03-11 18:13

【摘要】：薄膜材料是二维尺度的、具有特定性能和用途的材料，相关的薄膜技术是制备新型功能材料的有效手段。近年来，石墨烯、石墨烯基复合薄膜和氧化锌（ZnO）基复合薄膜在电极材料、太阳能电池、电子器件、储能器件、传感器和催化剂等领域展现出了优良的性能，具有非常广阔的应用前景。本论文采用等离子体增强化学气相沉积和物理气相沉积（磁控溅射）技术制备了石墨烯、石墨烯-TiO2多层复合薄膜和ZnO/Cu/ZnO三明治结构薄膜。利用拉曼（Raman）光谱、X射线衍射（XRD）、扫描电子显微镜（SEM）、透射电子显微镜（TEM）、原子力显微镜（AFM）、光纤光谱仪和四探针等测试手段，对薄膜的微结构、表面形貌、光电等性能进行了测试和分析，主要研究内容如下：（1）以Cu箔为催化基底，探索了PECVD制备石墨烯薄膜的条件，成功地在800oC下获得了高质量的单层石墨烯。主要研究了生长温度、甲烷（CH4）流量和氢气（H2）流量对石墨烯质量和层数的影响。发现随着生长温度的降低，石墨烯的缺陷以及层数逐渐增多，导电性迅速下降；较低的CH4流量（1sccm）有利于生成高质量的石墨烯，CH4流量的增加会造成石墨烯缺陷的增大；少量或者过量的H2都会给石墨烯的生长引入大量的缺陷，本实验中当H2流量为10sccm时石墨烯质量最优。（2）利用PECVD技术制备高质量的石墨烯薄膜，并将TiO2通过磁控溅射法直接沉积在石墨烯上制备了石墨烯-TiO2多层薄膜。通过比较沉积TiO2前后石墨烯的Raman光谱，，研究了石墨烯与TiO2之间的电荷转移情况。通过AFM研究了石墨烯的引入对TiO2形貌的影响，我们发现生长在石墨烯上的TiO2比表面积明显增大。通过甲基橙的光催化降解实验研究了石墨烯-TiO2复合膜的光催化性能，发现石墨烯薄膜的引入显著提高了TiO2降解甲基橙的效率。一方面是由于石墨烯作为电子接收材料能有效抑制TiO2中光生载流子的复合，另一方面则是由于石墨烯上生长的TiO2具有更大的比表面积，为光催化降解反应提供了更多的反应点，加快了催化进程。（3）采用磁控溅射技术在室温下制备了ZnO/Cu/ZnO三明治结构薄膜。先利用MATLAB编写程序模拟了ZnO/Cu/ZnO多层膜的透过率曲线来从理论上优化膜系结构从而指导实验。在实验中分别改变了ZnO层厚度、Cu层厚度和制备ZnO的O2/Ar流量比率，研究了它们对多层膜结构以及光电性能的影响。实验结果表明：随着ZnO层厚度的增加，膜系的方块电阻和可见光透过率逐渐增大；当ZnO厚度在40-70nm范围内时，多层膜表现出较好的透光性能，透过率曲线在整个可见光区域内较为平坦。在Cu层连续之前，随着Cu层厚度的增加，方块电阻逐渐减小，但紫外和可见光区的透过率都逐渐降低。O2/Ar流量比率为1:4时，多层膜的方块电阻最高，之后随着O2/Ar流量比率的继续升高，方块电阻又逐渐下降，这可能是由界面效应造成的。
[Abstract]:Thin film materials are two-dimensional scale materials with specific properties and applications. The related thin film technology is an effective method to fabricate new functional materials. In recent years, graphene-based composite film and zinc oxide (ZnO)-based composite film have shown excellent performance in the fields of electrode materials, solar cells, electronic devices, energy storage devices, sensors and catalysts, etc. It has a very broad application prospect. In this paper, graphene, graphene-TiO2 multilayer composite films and ZnO/Cu/ZnO sandwich films were prepared by plasma enhanced chemical vapor deposition and physical vapor deposition (magnetron sputtering). Raman (Raman) spectra, X-ray diffraction (XRD), scanning electron microscope (XRD), transmission electron microscope (TEM), atomic force microscope (AFM) (AFM), optical fiber spectrometer and four probes were used to characterize the microstructure of the thin films. The surface morphology and photoelectric properties were tested and analyzed. The main contents are as follows: (1) using Cu foil as catalyst substrate, the conditions of preparing graphene films by PECVD were explored, and high-quality monolayer graphene was successfully obtained under 800oC. The effects of growth temperature, flow rate of methane (CH4) and hydrogen (H _ 2) on the quality and layer number of graphene were studied. It was found that with the decrease of growth temperature, the defects and layers of graphene gradually increased and the conductivity decreased rapidly, and the low CH4 flow rate (1sccm) was beneficial to the formation of high quality graphene, and the increase of CH4 flow rate resulted in the increase of graphene defects. A small amount of H _ 2 or excess H _ 2 will lead to a lot of defects in the growth of graphene. In this experiment, the mass of graphene is the best when the flow rate of H _ 2 is 10sccm. (2) High quality graphene films were prepared by PECVD, and TiO2 was deposited on graphene by magnetron sputtering. Graphene-TiO2 multilayer films were prepared by magnetron sputtering. By comparing the Raman spectra of graphene before and after TiO2 deposition, the charge transfer between graphene and TiO2 was studied. The effect of graphene introduction on the morphology of TiO2 was studied by AFM. It was found that the specific surface area of TiO2 grown on graphene increased obviously. The photocatalytic performance of graphene-TiO2 composite film was studied by photocatalytic degradation of methyl orange. It was found that the effect of graphene film on the degradation of methyl orange by TiO2 was significantly improved. On the one hand, graphene can effectively inhibit the recombination of photogenerated carriers in TiO2 as an electron receiving material, on the other hand, the TiO2 grown on graphene has a larger specific surface area, which provides more reaction points for photocatalytic degradation reaction. The catalytic process has been accelerated. (3) ZnO/Cu/ZnO sandwich films were prepared by magnetron sputtering at room temperature. Firstly, the transmission curve of ZnO/Cu/ZnO multilayer film is simulated by MATLAB program to optimize the structure of the film system in theory so as to guide the experiment. The thickness of ZnO layer, the thickness of Cu layer and the O2/Ar flow ratio of ZnO were changed in the experiment, and their effects on the structure and photoelectric properties of multilayer films were studied. The experimental results show that the block resistance and visible light transmittance of the film increase with the increase of the thickness of the ZnO layer. When the thickness of ZnO is in the range of 40-70nm, the multilayer film exhibits better transmittance, and the transmittance curve is flat in the whole visible light region. Before the Cu layer is continuous, the block resistance decreases with the increase of the thickness of Cu layer, but the transmittance of ultraviolet and visible light decreases gradually. When the flow ratio of O2 / Ar is 1: 4, the block resistance of multilayer film is the highest. After that, as the O2/Ar flow ratio continues to increase, the block resistance gradually decreases, which may be caused by the interface effect.
【学位授予单位】：吉林大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TB383.2

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