点缺陷对石墨烯纳米材料电学性能影响的理论研究
发布时间：2018-08-18 15:26
【摘要】：石墨烯是由碳原子以sp2杂化键形成的网状体系结构,因其独特的物理结构而拥有良好的导电性能。在制备石墨烯的过程中很容易产生缺陷,缺陷和杂质的引入在很大程度上扩展了graphene的性能,进一步奠定了graphene在未来作为纳米电子器件发展首选材料的主要位置,而在实验上已经可以做到将graphene刻蚀成准一维的石墨烯纳米带(GNRs),并且实验上可以利用高能粒子轰击石墨烯产生缺陷,这也为今后的纳米电子器件的发展提供了坚实的实验基础,本文主要研究内容及结果有以下儿个方面：(1)采用第一性原理的计算方法研究了锯齿型GNRs中边缘结构重构形成的两种不同缺陷结构对材料电子输运性能的影响,研究发现两种缺陷边缘结构对稳定纳米尺度位型结构和电子能带结构具有显著影响,它使得费米能级发生移动并引起了共振背散射,两种边缘缺陷重构均抑制了费米能级附近电子输运特性并导致不同区域的电子完全共振背散射,电导的抑制不仅与边缘缺陷结构的大小有关,它更取决于边缘缺陷重构位型引起的缺陷态的具体分布和电子能带的移动。(2)采用第一性原理结合非平衡格林函数的计算方法研究了扶手椅型GNRs中双空位缺陷对材料电子结构和输运特性的影响,以理想的156个原子的扶手椅型GNRs为原始模型,将不同种类的双空位缺陷类型引入到纳米结构材料中,研究发现双空位缺陷的引入对材料的电子结构和输运特性均产生了一定的影响,它促使费米能级发生了迁移,其中555-777型缺陷结构相较于5-8-5型缺陷结构其转换能更低,更容易发生转化。其材料的输运特性对双空位缺陷的类型和双空位缺陷形成的位置有很强的依赖性。(3)采用第一性原理的计算方法研究了Co原子掺杂的扶手椅型GNRs电子结构的影响,以104个原子的扶手椅型GNRs为原始模型,将Co原子利用双空位取代掺杂引入到模型中,通过改变Co原子的掺杂位置和边缘C原子的自旋极化设置计算模拟材料的结构稳定性和电学性能,计算结果显示Co原子的引入增强了材料的磁学性质,并对材料的电学性能有一定的影响,能促使材料的费米能级面发生迁移,增强了材料的导电性能,在材料边缘C原子上加入自旋极化设置后能使整个材料趋于平面结构,其中自旋平行设置相较于其他设置更为稳定,材料的结构稳定性和电学性能在很大程度上由Co原子掺杂的位置和边缘C原子自旋极化设置决定。
[Abstract]:Graphene is a network of carbon atoms formed by SP2 hybrid bonds. Graphene has good electrical conductivity because of its unique physical structure. Defects are easy to occur in the process of preparing graphene. The introduction of defects and impurities greatly expands the properties of graphene and further lays a foundation for graphene as a nano-electron in the future. Graphene nanoribbons (GNRs) can be etched into graphene nanoribbons, and defects can be produced by bombarding graphene with high-energy particles. This provides a solid experimental basis for the development of nanoelectronic devices in the future. The results are as follows: (1) The effects of two different defect structures formed by edge structure reconstruction on the electronic transport properties of zigzag GNRs are studied by the first-principles method. It is found that the two defect edge structures have significant effects on stable nano-scale potential structure and electronic band structure. Both edge defect reconstruction suppress the electron transport near the Fermi level and lead to the full resonance backscattering of electrons in different regions. The suppression of conductivity depends not only on the size of the edge defect structure, but also on the defect state caused by the reconstructed potential of the edge defect. (2) The effects of double vacancy defects on the electronic structure and transport properties of armchair GNRs were studied by the first-principles method and the non-equilibrium Green's function method. Different types of double vacancy defects were introduced into the armchair GNRs with 156 atoms as the original model. In nanostructured materials, it is found that the introduction of double vacancy defects has a certain effect on the electronic structure and transport properties of the materials, which leads to the transfer of Fermi energy levels. The 555-777 type defect structure has lower conversion energy and is easier to be transformed than the 5-8-5 type defect structure. (3) The influence of Co atom doping on the electronic structure of armchair GNRs was studied by the first-principles method. The armchair GNRs with 104 atoms were used as the original model, and the Co atom was introduced into the model by substituting doping with double vacancies. The doping position of the electron and the spin polarization settings of the edge C atom are calculated to simulate the structural stability and electrical properties of the material. The results show that the introduction of Co atom enhances the magnetic properties of the material and affects the electrical properties of the material to a certain extent. It can promote the migration of the Fermi level surface of the material and enhance the conductivity of the material. The spin polarization settings on the edge C atom of the material can make the whole material tend to a planar structure. The spin parallel settings are more stable than other settings. The structural stability and electrical properties of the material are largely determined by the location of Co atom doping and the spin polarization settings of the edge C atom.
【学位授予单位】：长江大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.1
本文编号：2189890
[Abstract]:Graphene is a network of carbon atoms formed by SP2 hybrid bonds. Graphene has good electrical conductivity because of its unique physical structure. Defects are easy to occur in the process of preparing graphene. The introduction of defects and impurities greatly expands the properties of graphene and further lays a foundation for graphene as a nano-electron in the future. Graphene nanoribbons (GNRs) can be etched into graphene nanoribbons, and defects can be produced by bombarding graphene with high-energy particles. This provides a solid experimental basis for the development of nanoelectronic devices in the future. The results are as follows: (1) The effects of two different defect structures formed by edge structure reconstruction on the electronic transport properties of zigzag GNRs are studied by the first-principles method. It is found that the two defect edge structures have significant effects on stable nano-scale potential structure and electronic band structure. Both edge defect reconstruction suppress the electron transport near the Fermi level and lead to the full resonance backscattering of electrons in different regions. The suppression of conductivity depends not only on the size of the edge defect structure, but also on the defect state caused by the reconstructed potential of the edge defect. (2) The effects of double vacancy defects on the electronic structure and transport properties of armchair GNRs were studied by the first-principles method and the non-equilibrium Green's function method. Different types of double vacancy defects were introduced into the armchair GNRs with 156 atoms as the original model. In nanostructured materials, it is found that the introduction of double vacancy defects has a certain effect on the electronic structure and transport properties of the materials, which leads to the transfer of Fermi energy levels. The 555-777 type defect structure has lower conversion energy and is easier to be transformed than the 5-8-5 type defect structure. (3) The influence of Co atom doping on the electronic structure of armchair GNRs was studied by the first-principles method. The armchair GNRs with 104 atoms were used as the original model, and the Co atom was introduced into the model by substituting doping with double vacancies. The doping position of the electron and the spin polarization settings of the edge C atom are calculated to simulate the structural stability and electrical properties of the material. The results show that the introduction of Co atom enhances the magnetic properties of the material and affects the electrical properties of the material to a certain extent. It can promote the migration of the Fermi level surface of the material and enhance the conductivity of the material. The spin polarization settings on the edge C atom of the material can make the whole material tend to a planar structure. The spin parallel settings are more stable than other settings. The structural stability and electrical properties of the material are largely determined by the location of Co atom doping and the spin polarization settings of the edge C atom.
【学位授予单位】：长江大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.1
【参考文献】
相关期刊论文 前2条
1 王雪梅;刘红;;锯齿型石墨烯纳米带的能带研究[J];物理学报;2011年04期
2 邓小清;杨昌虎;张华林;;B/N掺杂对于石墨烯纳米片电子输运的影响[J];物理学报;2013年18期
，本文编号：2189890
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