單層二硫化鉬的光學(xué)性能及其調(diào)控研究
發(fā)布時間：2018-08-22 07:43
【摘要】：二維MoS_2具有優(yōu)異的光學(xué)及電學(xué)性能而成為近年來的研究熱點(diǎn)。高質(zhì)量、大尺寸單層MoS_2的制備仍然是一項具有挑戰(zhàn)性的課題,同時關(guān)于MoS_2的形狀演化機(jī)制及表面缺陷分布也沒有清晰的認(rèn)知。本文采用CVD(化學(xué)氣相沉積)制備二維MoS_2,探究單層MoS_2的生長過程及形狀演化機(jī)制,采用熒光及拉曼光譜來研究MoS_2表面缺陷分布,同時,通過探究BPO(過氧化苯甲酰)處理MoS_2樣品前后熒光及拉曼光譜mapping圖的變化,研究BPO對單層MoS_2光學(xué)性能的調(diào)控作用。在有氧體系中成功制備了高質(zhì)量、大尺寸MoS_2樣品,并對其進(jìn)行掃描電子顯微鏡(SEM)、原子力顯微鏡(AFM)、拉曼光譜(Raman)、熒光光譜(PL)表征。在CVD體系中引入氧氣可以調(diào)控制備實(shí)驗(yàn)中S:Mo的比值,同時減少反應(yīng)中的成核位點(diǎn)。采集MoS_2的拉曼光譜,發(fā)現(xiàn)隨著MoS_2層數(shù)的增多,E2g峰逐漸紅移,A1g峰逐漸藍(lán)移,單層MoS_2具有較強(qiáng)的熒光,且隨著MoS_2層數(shù)的增加,A激子峰強(qiáng)度逐漸減弱。以S:Mo比值為分類依據(jù),建立MoS_2形狀演化模型,闡述不同形狀MoS_2的演化過程。同三角形、四角形和五角形MoS_2熒光光譜相比,六角形MoS_2的熒光強(qiáng)度急劇增高,同時熒光特征峰藍(lán)移;采集MoS_2表面的熒光光譜,發(fā)現(xiàn)六角形MoS_2的缺陷集中分布在中心區(qū)域,而三角形MoS_2缺陷集中分布在頂角及邊界。采集BPO處理MoS_2樣品前后的熒光及拉曼光譜mapping圖,發(fā)現(xiàn)MoS_2樣品被BPO處理后,三角形MoS_2的邊緣區(qū)域的熒光強(qiáng)度增加,同時拉曼峰A1g峰藍(lán)移,且隨著激光功率的增加,B激子峰和A激子峰強(qiáng)度逐漸增大,且A激子峰強(qiáng)度增加的幅度比B激子峰增加的幅度更大。我們認(rèn)為導(dǎo)致熒光增強(qiáng),拉曼峰A1g峰藍(lán)移的原因可能是BPO成功的修飾了MoS_2,或者是一種化學(xué)吸附機(jī)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.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TN304
本文編號：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.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TN304
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