快重离子辐照二维MoX2材料微观缺陷演化及电学性能影响研究

Recently, the development of the two dimensional（2D）materials MoX2 has been boosted as they have excellent photoelectric property. While the investigations of influences of defects on the properties of MoX2 are still in its infancy. As we all known, the controllable introduced process of defects is important to achieve the functions of the materials. Herein, MoS2 and MoSe2 with different layers are irradiated by swift heavy ions（Kr, Xe, Bi ions）with different irradiation parameters to introduce defects in a controlled manner. Defects in the irradiated MoS2 and MoSe2 will be investigated by high resolution transmission electron microscope (HREM), scanning probe microscopy (SPM), Raman spectroscopy, photoluminescence spectroscopy (PL) and ultraviolet-visible spectrum (UV-vis). On the one hand, the relationships between defects of the irradiated samples and the irradiation parameters such as ion energy, fluences and electronic energy loss, will be concerned in this study. The interaction mechanism between swift heavy ion and 2D materials MoX2 will be accounted. On the other hand, the influences of the defects on the materials’ electrical properties will be discussed combined with computer simulations. The mechanism of electrical property modifications of MoX2 irradiated by swift heavy ions will be explained. It will provide a basis for how to regulate the band gap and photoelectric properties of MoX2 materials. It is also of great significance to intensify the knowledge and research of the effects of swift heavy ion irradiation in 2D materials.

二维MoX2材料由于易解理成薄层材料，且具有优异的物理化学性能而受到广泛关注，但二维MoX2材料中的缺陷对于其性能的影响尚缺乏深入研究。众所周知，缺陷的可控引入过程是材料实现功能化的重要途径，而对缺陷在材料物理过程中所起作用研究是精确调控材料功能的基础。因此，本项目拟通过快重离子(Kr、Xe、Bi等)辐照可控地在MoS2和MoSe2材料中引入缺陷。结合高分辨分析测试和第一性原理模拟，一方面，分析快重离子辐照产生微观缺陷及其随辐照参数和材料层数的变化规律，探讨快重离子辐照MoX2材料缺陷演化机理。另一方面，研究缺陷对材料电导率、激子跃迁、带隙等电学性能的影响，揭示快重离子辐照对二维MoX2材料电学性能的影响机制，为在更大自由度调控MoX2材料带隙等电学性能提供依据，为由MoX2材料制备的电子器件的应用可靠性提供最原始的实验基础，同时，对于新一代半导体器件应用于空间辐射环境具有重要指导意义。

二维MoX2材料由于易解理成薄层材料，具有可调带隙，且具有优异的物理化学性能而受到广泛关注。然而由于二维材料在制备、转移等过程中不可避免的存在缺陷，半导体材料中的缺陷可以称之为“双刃剑”，对其电学性能有极大的影响。因此，本课题通过荷能重离子辐照技术可控的在材料中引入缺陷，研究重离子辐照缺陷的精细结构，及缺陷对MoX2材料光学性能及其电学性能的影响。研究发现，重离子辐照在少层MoSe2中引入了均匀分布的潜径迹缺陷，径迹芯为非晶态，周围保持规则晶格条纹。重离子辐照缺陷与衬底、样品厚度等均有密切关系，在MoSe2表面，潜径迹缺陷的高度不光与样品厚度有关，且与衬底的种类及其晶体取向密切相关。在MoS2中，径迹形貌随样品的厚度呈现出不同形貌。重离子辐照还可引起单层WS2样品中带电激子向中性激子转变，且在一定注量下，能够导致WS2/MoS2异质结产生间接带隙-直接带隙转变。重离子辐照引起MoSe2基场效应晶体管载流子迁移率随注量的增大呈先增大后减小的趋势。本项目的进行为在更大自由度调控MoX2材料带隙等电学性能提供依据，为由MoX2材料制备的电子器件的应用可靠性提供最原始的实验基础，同时，对于新一代半导体器件应用于空间辐射环境具有重要指导意义。