Ⅳ-Ⅵ族硫族化合物层状半导体及其异质结构的第一性原理研究
发布时间：2019-05-08 08:45
【摘要】：低维纳米材料由于其新颖的物理化学性质和在多个领域都有很好的潜在应用而成为了当今纳米材料研究的前沿和热点,对能源、信息等领域有着越来越深远的影响。基于第一性原理的密度泛函理论(density functional theory,DFT)在纳米材料的微观设计和性能预测方面是应用非常广泛而且行之有效的方法。本论文即是利用DFT对IV-VI族硫族化合物层状半导体及其异质结构进行系统的研究。首先,我们研究了SnSe2和SnS2形成的固熔体异质结构,并从其稳定性、电子结构和光学性质及其调制等方面进行了具体和系统的研究。其次,我们探讨了类黑磷材料MXs(M=Sn,Ge;X=Se,S)的性质,并重点讨论了层数对这些性质的影响;最后,根据能带带边对齐的计算,探讨了类黑磷材料相互之间以及黑磷与类黑磷材料之间形成II-型异质结构的可能性,并进一步提出通过改变层数,可以实现II-I以及I-II型异质结构的转变。本论文一共分为六个章节,第一章主要介绍了IV-VI族硫族化合物层状结构材料的研究现状以及本论文的研究背景、研究目标和研究内容。第二章简要的阐述了密度泛函理论以及第一性原理计算所需要的VASP软件包。第三章中我们对SnSe2(1-x)S2x合金的稳定性、电子结构和光学性质做了系统性地研究。我们发现SnSe2和SnS2在温度高于702K时能形成“随机”合金,且上下层硫原子掺杂数目趋向于相同。随着硫原子浓度的增大,合金体系的带隙值非线性减小,且光学性质呈现各向异性并在可见光区域合金呈现更为明显的吸收峰。第四章中我们研究了MXs体相结构以及单层、多层结构的稳定性、电子结构、光学性质和有效质量,重点讨论了层数对这些性质的影响。研究发现,随着层数的增加,体系变得更加稳定,带隙值变小且与层数的倒数表现出极好的线性关系(GeS除外)。光学性质研究发现,所有的单层、多层MXs均表现出各向异性,特别是Sn S和Sn Se体系在可见光区域具有很强的吸收。对有效质量的计算发现只有Sn S单层和多层结构的电子有效质量是随着层数的增加而递减的,其他体系没有看到明显的规律。在第五章中,我们先通过对MXs和磷烯的能带带边位置的计算,探讨了MXs相互之间以及它们与黑磷之间形成II-型异质结构的可能性,并进一步研究了异质结层依赖的电子性能。通过构建Moiré模式,证实了可以通过改变层数来实现异质结从I到II型或者II到I型的转变。第六章是对论文的总结和展望。
[Abstract]:Because of its novel physical and chemical properties and potential applications in many fields, low-dimensional nano-materials have become the frontier and hot spot of nano-materials research, and have more and more far-reaching influence on energy, information and other fields. Density functional theory (density functional theory,DFT) based on first-principles is a widely used and effective method in micro-design and performance prediction of nano-materials. In this thesis, DFT is used to systematically study the layered semiconductor and its heterostructure of IV-VI chalcogenide compounds. Firstly, the solid melt heterostructures formed by SnSe2 and SnS2 have been studied, and their stability, electronic structure, optical properties and modulation have been studied in detail and systematically. Secondly, we discussed the properties of black-like phosphorus-like material MXs (M-Si-Sn, GE-X-se, S), and discussed the influence of layers on these properties. Finally, according to the calculation of band edge alignment, the possibility of forming II- heterostructure between black phosphorus-like materials and black phosphorus-like materials is discussed, and it is further suggested that the layer number can be changed by changing the number of layers. The transformation of II-I and I-II heterostructure can be realized. This thesis is divided into six chapters. The first chapter mainly introduces the research status of IV-VI chalcogenide layered structure materials, the research background, the research goal and the research content of this thesis. In chapter 2, the density functional theory (DFT) and the VASP software package for first-principle calculation are briefly described. In chapter 3, we systematically study the stability, electronic structure and optical properties of SnSe2 (1 x) S 2x alloy. It is found that SnSe2 and SnS2 can form "random" alloys at temperatures higher than 702K, and the doping number of sulfur atoms in the upper and lower layers tends to be the same. With the increase of sulfur atom concentration, the band gap value of the alloy system decreases non-linearly, and the optical properties of the alloy show anisotropy and a more obvious absorption peak in the visible light region. In chapter 4, we study the stability, electronic structure, optical properties and effective mass of the bulk phase structure and monolayer and multilayer structure of MXs, and discuss the influence of the number of layers on these properties. It is found that with the increase of the number of layers, the system becomes more stable, and the band gap becomes smaller and has a good linear relationship with the reciprocal of the layers (except GeS). It is found that all monolayer and multilayer MXs exhibit anisotropy, especially the Sn S and Sn Se systems have strong absorption in the visible region. It is found that the electron effective mass of only Sn S monolayer and multilayer structure decreases with the increase of the number of layers, but no obvious rule is found in other systems. In chapter 5, by calculating the band edge positions of MXs and phosphene, we discuss the possibility of forming II- type heterostructures between MXs and phosphene, and further study the electronic properties of heterojunction layer dependence. By constructing Moir 茅 model, it is proved that the transformation of heterojunction from type I to type II or from II to type I can be achieved by changing the number of layers. The sixth chapter is the summary and prospect of the thesis.
【学位授予单位】：安徽师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB383.1
本文编号：2471770
[Abstract]:Because of its novel physical and chemical properties and potential applications in many fields, low-dimensional nano-materials have become the frontier and hot spot of nano-materials research, and have more and more far-reaching influence on energy, information and other fields. Density functional theory (density functional theory,DFT) based on first-principles is a widely used and effective method in micro-design and performance prediction of nano-materials. In this thesis, DFT is used to systematically study the layered semiconductor and its heterostructure of IV-VI chalcogenide compounds. Firstly, the solid melt heterostructures formed by SnSe2 and SnS2 have been studied, and their stability, electronic structure, optical properties and modulation have been studied in detail and systematically. Secondly, we discussed the properties of black-like phosphorus-like material MXs (M-Si-Sn, GE-X-se, S), and discussed the influence of layers on these properties. Finally, according to the calculation of band edge alignment, the possibility of forming II- heterostructure between black phosphorus-like materials and black phosphorus-like materials is discussed, and it is further suggested that the layer number can be changed by changing the number of layers. The transformation of II-I and I-II heterostructure can be realized. This thesis is divided into six chapters. The first chapter mainly introduces the research status of IV-VI chalcogenide layered structure materials, the research background, the research goal and the research content of this thesis. In chapter 2, the density functional theory (DFT) and the VASP software package for first-principle calculation are briefly described. In chapter 3, we systematically study the stability, electronic structure and optical properties of SnSe2 (1 x) S 2x alloy. It is found that SnSe2 and SnS2 can form "random" alloys at temperatures higher than 702K, and the doping number of sulfur atoms in the upper and lower layers tends to be the same. With the increase of sulfur atom concentration, the band gap value of the alloy system decreases non-linearly, and the optical properties of the alloy show anisotropy and a more obvious absorption peak in the visible light region. In chapter 4, we study the stability, electronic structure, optical properties and effective mass of the bulk phase structure and monolayer and multilayer structure of MXs, and discuss the influence of the number of layers on these properties. It is found that with the increase of the number of layers, the system becomes more stable, and the band gap becomes smaller and has a good linear relationship with the reciprocal of the layers (except GeS). It is found that all monolayer and multilayer MXs exhibit anisotropy, especially the Sn S and Sn Se systems have strong absorption in the visible region. It is found that the electron effective mass of only Sn S monolayer and multilayer structure decreases with the increase of the number of layers, but no obvious rule is found in other systems. In chapter 5, by calculating the band edge positions of MXs and phosphene, we discuss the possibility of forming II- type heterostructures between MXs and phosphene, and further study the electronic properties of heterojunction layer dependence. By constructing Moir 茅 model, it is proved that the transformation of heterojunction from type I to type II or from II to type I can be achieved by changing the number of layers. The sixth chapter is the summary and prospect of the thesis.
【学位授予单位】：安徽师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB383.1
【参考文献】
相关期刊论文 前1条
1 张胜利;刘尚果;黄世萍;蔡波;谢美秋;渠莉华;邹友生;胡自玉;余学超;曾海波;;单层硒化锗多形体的结构特性和电子性质（英文）[J];Science China Materials;2015年12期
，本文编号：2471770
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