蜂窝状石墨烯、硅烯电子结构的界面效应研究

发布时间：2019-01-07 09:47

【摘要】：界面对材料的性能起着十分重要的作用。由于界面的存在,使得界面处电荷的分布与块体材料明显不同。因此,界面对材料的电子性质、输运性质、化学吸附、力学性质、各向异性等性能产生十分重要的影响。材料的界面设计逐渐成为了调控材料性质的重要手段,特别是在二维材料中,界面结构的设计是提高材料光催化性能、储存性能的重要手段。本论文主要以第一性原理为手段,研究了C_2N与石墨烯异质结的电子性质和硅烯的小角晶界结构,其主要结论如下:一、C_2N/Graphene(C_2N/G)异质结研究。利用第一性原理计算,我们系统研究了石墨烯与C_2N构成的层间异质结(范德瓦尔斯异质结)和面内异质结的电子结构特征。计算结果表明,这两类异质结中,石墨烯的带隙均被打开。对于层间异质结,石墨烯的带隙打开被是由对称性被破坏所导致的,其带隙宽度可通过调节层间距加以调控。对于面内异质结,量子限域效应导致石墨烯的带隙被打开,其带隙宽度随着石墨烯的宽度增大而减小。这些结果表明C_2N/Graphene异质结不仅能被用于制作高性能FETs的电子材料和还能用于光催化水分解。二、硅烯晶界的研究。利用第一性原理,我们探讨了硅烯晶界模型。值得特别指出的是,当矢量(?)与(?)两矢量的夹角为60°时,将形成一类无缝晶界。计算表明这类无缝晶界的形成能与晶胞形状、方向并无关联,仅取决于晶界的宽度,且与宽度呈正比关系。最后我们采用第一性原理模拟了该晶界的STM图像,发现晶面处的原子的亮度明显高于其他原子。STM模拟有助于实验观测者辨认无缝晶界模型。
[Abstract]:The interface plays a very important role in the properties of materials. Because of the existence of interface, the distribution of electric charge at interface is obviously different from that of bulk material. Therefore, the interface has a very important effect on the electronic properties, transport properties, chemical adsorption, mechanical properties and anisotropy of the materials. The interface design of materials has gradually become an important means to control the properties of materials. Especially in two-dimensional materials, the design of interface structure is an important means to improve the photocatalytic performance and storage performance of materials. In this thesis, the electronic properties of C _ 2N and graphene heterojunction and the small angle grain boundary structure of silicene have been studied by means of first-principles. The main conclusions are as follows: 1. C_2N/Graphene (C_2N/G) heterojunction. Using first-principle calculations, we systematically study the electronic structure characteristics of interlaminar heterostructure (van der Waals heterojunction) and in-plane heterojunction between graphene and C _ 2N. The results show that the band gap of graphene is opened in these two kinds of heterojunction. For interlaminar heterojunctions, the band gap opening of graphene is caused by the symmetry being broken, and its band gap width can be adjusted by adjusting the interlayer spacing. For in-plane heterojunction, the band gap of graphene is opened due to the quantum limiting effect, and the band gap width decreases with the increase of the width of graphene. These results indicate that C_2N/Graphene heterostructures can be used not only as electronic materials for high performance FETs but also for photocatalytic water decomposition. Second, the study of the grain boundary of silicene. Based on the first principle, the grain boundary model of silicene is discussed. It is worth noting that when a vector (?) With (?) A class of seamless grain boundaries will be formed when the angle between the two vectors is 60 掳. The calculation shows that the formation energy of this kind of seamless grain boundary is not related to the shape and direction of the crystal cell, but only depends on the width of the grain boundary and is proportional to the width of the grain boundary. Finally, we simulate the STM image of the grain boundary by first principle, and find that the brightness of atoms at the crystal plane is obviously higher than that of other atoms. The STM simulation is helpful to the identification of the seamless grain boundary model by the experimental observers.
【学位授予单位】：湘潭大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O613.7

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