论文总字数：39225字

摘 要

新材料是“中国制造2025”的十大重点研究领域之一，它要求做好前沿材料的提前布局和研制。二维材料由于具有原子级薄的厚度，展现出了超薄、柔性、高强度、能带可调、量子效应强等物理特性，是目前研究最热的新材料之一。层状二硫化钼（MoS₂）是一种二维半导体材料，多层MoS₂到单层MoS₂会发生间接带隙至直接带隙的转变，使其在未来光电子器件中展现出巨大的应用潜力。但是，本征MoS₂的外量子效率较低，且发光过程难以动态变化。本文以MoS₂为研究对象，利用机械剥离方法制备了高质量的单层MoS₂，并在此基础上利用紫外臭氧（UVO）处理MoS₂，实现了MoS₂发光的动态调控。本课题主要工作如下：

1、采用机械剥离方法制备了大量单层MoS₂样品，利用UVO处理MoS₂并结合光致发光(PL)光谱研究了UVO对MoS₂发光性质的影响。系统地研究了不同UVO处理时间和不同激光功率下UVO处理MoS₂的效果。我们发现，UVO处理可以动态调控MoS₂多种发光过程，包括发光的猝灭、自修复和增强。通过对比3、5、7和9 min的UVO处理时间，发现不同处理时间都能产生动态调控发光的效果，但是随着处理时间的增加，MoS₂发光动态变化的时间增长。对比10、50和250 μw激光功率，发现小功率10 μw无法使MoS₂发光自修复，50 μw及以上都能实现多个发光过程。

2、在UVO动态调控MoS₂发光的基础上，我们进一步研究了UVO处理的时效性，发现UVO处理效果至少可以保持6个小时以上。并且，用干法转移的手段将MoS₂与图案化的六角碳化硼(BN)做成异质结，利用PL成像结合UVO处理对MoS₂发光的动态调控进行了防伪加密应用上的探索。

关键词：二维材料 二硫化钼 光致发光 紫外臭氧处理

ABSTRACT

New materials are one of the ten key research areas of "Made in China 2025". It asks for making the layout of advanced materials in advance. Due to its atomic-thin thickness, two-dimensional materials exhibit physical characteristic of being ultra-thin and flexible, having high-strength and adjustable energy band, showing strong quantum effect, etc. Currently two-dimensional materials are one of the hottest new materials. Layered molybdenum disulfide (MoS₂) is a kind of two-dimensional semiconductor material. The transition from an indirect band gap semiconductor to a direct band gap semiconductor occurs between a multilayer MoS₂ and a monolayer MoS₂, which makes MoS₂ a promising material in future optoelectronic devices. However, the intrinsic MoS₂ luminescence shows low external quantum efficiency, and the luminescence process is difficult to change dynamically. In this paper, MoS₂ is taken as the research object, high-quality single-layer MoS₂ is mechanically exfoliated from bulk MoS₂ crystal, and ultraviolet ozone (UVO) is used to treat MoS₂. The dynamic regulation of MoS₂ luminescence is realized. The main work of this paper is listed as follows:

1. A large number of single-layer MoS₂ samples were prepared by mechanical exfoliation. The effect of UVO on the optical properties of MoS₂ was studied by combining UVO treatment and PL spectra. The effect of UVO treatment of MoS₂ under different treatment time and different laser power was systematically studied. We found that UVO treatment can dynamically regulate various luminescence processes of MoS₂, including luminescence quenching, self-repair and enhancement. By comparing the UVO treatment time of 3, 5, 7, 9 minutes, we found that different treatment time can all produce the effect of dynamic luminescence. But as the treatment time increases, the dynamic time range for the MoS₂ luminescence increases. Compared with 10 μw, 50 μw and 250 μw laser power, it is found that low power 10 μw can not make MoS₂ luminescence self-repair, 50 μw and above can realize all luminescence processes.

2. On the basis of discovering that UVO treatment can dynamically regulate the luminescence of MoS₂, we further studied the timeliness of UVO treatment. We found that the UVO treatment effect can be maintained for at least 6 hours. Besides, the MoS₂ and patterned BN were made into a heterojunction by dry transfer method. PL mapping and UVO treatment were used to explore applications in security encryption.

KEYWORDS: Two-dimensional materials; MoS₂; Photoluminescence; UVO treatment

目 录

摘 要 I

ABSTRACT II

第一章 绪论 1

1.1 二维材料概述 2

1.1.1 典型二维材料 3

1.1.2 二维材料的制备方法 5

1.2 MoS₂简介 9

1.2.1 MoS₂的晶格结构 9

1.2.2 MoS₂的能带结构 11

1.2.3 MoS₂光学性质的调控 12

第二章 MoS₂纳米片的制备及UVO处理 19

2.1 MX₂材料的单晶生长 19

2.2 MoS₂纳米片制备 19

2.3 UVO处理MoS₂ 22

第三章 UVO对MoS₂发光行为的动态调控 24

3.1 光学性质的测量 24

3.1.1 UVO 3min处理 24

3.1.2 UVO 5min处理 26

3.1.3 UVO 7min处理 28

3.1.4 UVO 9min处理 30

3.1.5 小结 32

3.2 光学性质测量结果分析 32

3.3 本章小结 37

第四章 总结与展望 39

4.1 工作总结 39

4.2 未来展望 39

参考文献 41

附 录 47

致 谢 49

第一章 绪论

材料的变革主导了人类文明的发展，我们已经经过了石器时代、青铜时代、铁器时代、蒸汽时代、电气时代，至当今的信息时代。自上个世纪50年代贝尔实验室三位科学家巴丁、肖克来、布拉顿发明晶体管以来，以微电子为代表的信息技术产业迎来了飞速的发展。因特尔公司创始人之一戈登·摩尔曾经提出了著名的摩尔定律——集成电路上可容纳的晶体管数目，每18个月便会增加一倍，性能也将提升一倍。摩尔定律已经延续了半个多世纪，以硅材料为基础的微电子工业已经发展到逼近其物理极限，晶体管线宽已经微缩到纳米，这时材料的物性将发生巨大的变化且存在量子效应，将造成器件的漏电和高温，导致器件失效。物理上门槛，成本及技术难度的增加等都给延续摩尔定律带来了巨大的技术挑战。因此，国际半导体技术路线图（ITRS）中提出了“More than Moore”和“beyond CMOS”的方案，希望探索新的器件和寻找新材料来代替传统硅基器件，提高性能和降低功耗。 图1-1展示了场效应晶体管（FET）发展路线图，微缩晶体管可以获得更低功耗、更强处理能力及更低的成本。

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