过渡金属硫化物缺陷结构演变研究

论文总字数：26574字

摘 要

本文使用透射电子显微镜（Transmission Electron Microscope TEM）,研究了电子束辐照下单层二硫化钼中点缺陷、线缺陷的结构与演变。

主要工作包括：第一，概述了二维材料与二硫化钼的原子结构与物理性质，介绍了国内外对单层二硫化钼电子辐照效应研究的进展与不足之处；第二，介绍了课题的理论知识基础，包括电子显微学与电子辐照效应；第三，介绍了研究使用的实验方法、数据处理软件与分析方法；第四，鉴别了电子束辐照下单层二硫化钼中的点缺陷与线缺陷结构，对点缺陷与线缺陷结构进行了动态表征。

鉴别了四种点缺陷，包括一个单硫原子空位（V_S）、一个双硫原子空位（V_S2）、一个钼原子取代一个 S2 列（Mo_S2）的反位缺陷、一个 S2列取代一个钼原子的反位缺陷（S2_Mo）；通过分析单硫空位数目随辐照剂量的演变关系估算了单硫原子的散射截面对比实验结果与理论值，探讨了二者之间差异的来源。

鉴别了one-sided和staggered两种类型的线缺陷，通过分析图像序列，在现有理论的基础上解释了线缺陷结构演变的机理。

关键词：单层二硫化钼，电子辐照，点缺陷，线缺陷

Abstract

In this thesis, transmission electron microscope (TEM) was used to study the structure and structural evolution of point defects and line defects in monolayer molybdenum disulfide under electron beam irradiation. The organization of this thesis is as follows: Firstly, the atomic structure and physical properties of two-dimensional materials including molybdenum disulfide are summarized. The research progress in research on the electron irradiation effect of monolayer molybdenum disulfide at home and abroad is briefly reviewed. Secondly, the basic theory of the subject is discussed, including electron microscopy and electron irradiation effects; thirdly, the experimental methods, data processing software and analytical methods used in the study are presented; fourthly, several types of point defects and line defects in monolayer molybdenum disulfide are identified, and the structural evolution of point defect and line defect under electron beam irradiation are monitored separately.

Four types of point defects were identified, including a single sulfur atom vacancy (V_S), a double sulfur atom vacancy (V_S2), a molybdenum atom replacing an S2 column (Mo_S2), and a S2 column replacing a molybdenum atom (S2_Mo). Then, the scattering cross section of S atoms was estimated after analyzing the relationship between the number of V_S and electron dose. Moreover, the results were compared with the theoretical values and the deviations were analyzed.

Two types of line defects, including one-sided and staggered were identified. By analyzing the image sequence, the mechanism of the structural evolution of line defect structure was proposed on the basis of the existing theory.

Keywords: monolayer molybdenum disulfide, electron beam irradiation, point defects, line defects

目 录

摘要 I

Abstract II

目 录 III

第一章 绪论 1

1.1 研究背景 1

1.1.1 二维材料 1

1.1.2 二硫化钼简介 2

1.2 国内外研究现状 4

1.3 课题研究内容及意义 5

1.4 论文结构 6

第二章 透射电子显微学与电子辐照效应 7

2.1 透射电子显微学 7

2.1.1 简介 7

2.1.2 透射电子显微镜的构造与原理[19,20] 7

2.1.3 原位透射电子显微术 9

2.2 电子辐照效应 9

2.2.1 简介 9

2.2.2 弹性散射效应 10

2.2.3 非弹性散射效应 11

2.3 本章小结 12

第三章 点缺陷鉴别与动态表征 13

3.1 引言 13

3.2 实验方法 13

3.2.1 样品制备 13

3.2.2 样品转移 14

3.2.3 TEM表征 15

3.3 分析软件 15

3.3.1 Digital Micrograph 15

3.3.2 Materials Studio 18

3.3.3 Origin 18

3.4 点缺陷结构分析 19

3.4.1 分析方法 19

3.4.2 实验数据处理 21

3.4.3 实验结果分析 26

3.5 点缺陷的演变 26

3.5.1 散射截面计算方法 26

3.5.2 实验数据处理 27

3.5.3 实验结果分析 30

3.6 本章小结 31

第四章 线缺陷鉴别与动态表征 32

4.1 引言 32

4.2 线缺陷结构分析 32

4.2.1 分析方法 32

4.2.2 实验数据处理 34

4.3 线缺陷的形成及演变 35

4.4 实验结果分析 38

4.5 本章小结 38

第五章 总结与展望 39

5.1 总结 39

5.2 展望 39

致 谢 40

参考文献 41

绪论

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