单层二硫化钼的光学性能及其调控研究
发布时间：2018-08-22 07:43
【摘要】：二维MoS_2具有优异的光学及电学性能而成为近年来的研究热点。高质量、大尺寸单层MoS_2的制备仍然是一项具有挑战性的课题,同时关于MoS_2的形状演化机制及表面缺陷分布也没有清晰的认知。本文采用CVD(化学气相沉积)制备二维MoS_2,探究单层MoS_2的生长过程及形状演化机制,采用荧光及拉曼光谱来研究MoS_2表面缺陷分布,同时,通过探究BPO(过氧化苯甲酰)处理MoS_2样品前后荧光及拉曼光谱mapping图的变化,研究BPO对单层MoS_2光学性能的调控作用。在有氧体系中成功制备了高质量、大尺寸MoS_2样品,并对其进行扫描电子显微镜(SEM)、原子力显微镜(AFM)、拉曼光谱(Raman)、荧光光谱(PL)表征。在CVD体系中引入氧气可以调控制备实验中S:Mo的比值,同时减少反应中的成核位点。采集MoS_2的拉曼光谱,发现随着MoS_2层数的增多,E2g峰逐渐红移,A1g峰逐渐蓝移,单层MoS_2具有较强的荧光,且随着MoS_2层数的增加,A激子峰强度逐渐减弱。以S:Mo比值为分类依据,建立MoS_2形状演化模型,阐述不同形状MoS_2的演化过程。同三角形、四角形和五角形MoS_2荧光光谱相比,六角形MoS_2的荧光强度急剧增高,同时荧光特征峰蓝移;采集MoS_2表面的荧光光谱,发现六角形MoS_2的缺陷集中分布在中心区域,而三角形MoS_2缺陷集中分布在顶角及边界。采集BPO处理MoS_2样品前后的荧光及拉曼光谱mapping图,发现MoS_2样品被BPO处理后,三角形MoS_2的边缘区域的荧光强度增加,同时拉曼峰A1g峰蓝移,且随着激光功率的增加,B激子峰和A激子峰强度逐渐增大,且A激子峰强度增加的幅度比B激子峰增加的幅度更大。我们认为导致荧光增强,拉曼峰A1g峰蓝移的原因可能是BPO成功的修饰了MoS_2,或者是一种化学吸附机制。
[Abstract]:Two-dimensional MoS_2 with excellent optical and electrical properties has become a research hotspot in recent years. The preparation of high quality, large size monolayer MoS_2 is still a challenging subject, and there is no clear understanding of the shape evolution mechanism and surface defect distribution of MoS_2. In this paper, CVD (Chemical Vapor deposition) was used to prepare two-dimensional MoS _ 2, to investigate the growth process and shape evolution mechanism of monolayer MoS_2, to study the distribution of defects on MoS_2 surface by fluorescence and Raman spectroscopy, at the same time, The effects of BPO (benzoyl peroxide) on the optical properties of monolayer MoS_2 were studied by investigating the changes of fluorescence and Raman spectra of mapping before and after MoS_2 treatment. High quality and large size MoS_2 samples were successfully prepared in aerobic system and characterized by scanning electron microscope (SEM) (SEM), atomic force microscope (SEM),) (AFM), Raman spectroscopy (AFM),) (Raman), fluorescence spectrum (PL). The addition of oxygen to CVD system can regulate the ratio of S:Mo in the preparation experiment and decrease the nucleation sites in the reaction. The Raman spectra of MoS_2 show that with the increase of the number of layers of MoS_2, the peak of E2g shifts red and the peak of A1g gradually shifts blue, and monolayer MoS_2 has strong fluorescence, and the intensity of exciton peak weakens with the increase of the number of layers of MoS_2. Based on the S:Mo ratio, the MoS_2 shape evolution model is established, and the evolution process of MoS_2 with different shapes is described. Compared with the fluorescence spectra of triangular, tetragonal and pentagonal MoS_2, the fluorescence intensity of hexagonal MoS_2 increases sharply and the characteristic peak of fluorescence shifts blue. The fluorescence spectra of MoS_2 surface show that the defects of hexagonal MoS_2 are concentrated in the central region. The triangular MoS_2 defects are distributed in the parietal angle and the boundary. The fluorescence and Raman spectra of MoS_2 samples before and after BPO treatment were collected. It was found that the fluorescence intensity of the edge region of triangular MoS_2 increased and the blue shift of A1g peak of MoS_2 samples was observed after BPO treatment. With the increase of laser power, the intensity of B exciton peak and A exciton peak increase gradually, and the amplitude of A exciton peak increase is larger than that of B exciton peak. We believe that the blue shift of Raman peak A1g may be due to the successful modification of BPO or a chemisorption mechanism.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN304
本文编号：2196450
[Abstract]:Two-dimensional MoS_2 with excellent optical and electrical properties has become a research hotspot in recent years. The preparation of high quality, large size monolayer MoS_2 is still a challenging subject, and there is no clear understanding of the shape evolution mechanism and surface defect distribution of MoS_2. In this paper, CVD (Chemical Vapor deposition) was used to prepare two-dimensional MoS _ 2, to investigate the growth process and shape evolution mechanism of monolayer MoS_2, to study the distribution of defects on MoS_2 surface by fluorescence and Raman spectroscopy, at the same time, The effects of BPO (benzoyl peroxide) on the optical properties of monolayer MoS_2 were studied by investigating the changes of fluorescence and Raman spectra of mapping before and after MoS_2 treatment. High quality and large size MoS_2 samples were successfully prepared in aerobic system and characterized by scanning electron microscope (SEM) (SEM), atomic force microscope (SEM),) (AFM), Raman spectroscopy (AFM),) (Raman), fluorescence spectrum (PL). The addition of oxygen to CVD system can regulate the ratio of S:Mo in the preparation experiment and decrease the nucleation sites in the reaction. The Raman spectra of MoS_2 show that with the increase of the number of layers of MoS_2, the peak of E2g shifts red and the peak of A1g gradually shifts blue, and monolayer MoS_2 has strong fluorescence, and the intensity of exciton peak weakens with the increase of the number of layers of MoS_2. Based on the S:Mo ratio, the MoS_2 shape evolution model is established, and the evolution process of MoS_2 with different shapes is described. Compared with the fluorescence spectra of triangular, tetragonal and pentagonal MoS_2, the fluorescence intensity of hexagonal MoS_2 increases sharply and the characteristic peak of fluorescence shifts blue. The fluorescence spectra of MoS_2 surface show that the defects of hexagonal MoS_2 are concentrated in the central region. The triangular MoS_2 defects are distributed in the parietal angle and the boundary. The fluorescence and Raman spectra of MoS_2 samples before and after BPO treatment were collected. It was found that the fluorescence intensity of the edge region of triangular MoS_2 increased and the blue shift of A1g peak of MoS_2 samples was observed after BPO treatment. With the increase of laser power, the intensity of B exciton peak and A exciton peak increase gradually, and the amplitude of A exciton peak increase is larger than that of B exciton peak. We believe that the blue shift of Raman peak A1g may be due to the successful modification of BPO or a chemisorption mechanism.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN304
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