Study On Electron Transport Properties Of Low-dimensional Boron And Carbon-based Nanostructures

In recent years,with the deepening of people's understanding and the development of science and technology,a series of low-dimensional nanostructures such as fullerenes,various cluster molecules,nanowires,nanoribbons,nanotubes,and graphene have been discovered and synthesized which shows their peculiar electrical properties.Explorations of other nanomaterials with excellent properties have been ongoing.Limited by the characteristics of the application environment?such as device line width,integration,etc.?,low-dimensional?two-dimensional,one-dimensional,zero-dimensional?nanostructures are the most ideal constituent materials for nanoelectronic devices.The discovery of various low-dimensional nanostructures has brought broader application potential and prospects to nanoelectronic devices.In recent years,carbon-based nanostructures such as graphene have been extensively studied.At the same time,boron-based nanostructures composed of boron elements adjacent to carbon on the periodic table are continuously synthesized and found,exhibiting excellent characteristics.In this paper,under the first principle of quantum mechanics,the electron transport properties and intrinsic mechanism of low-dimensional boron-based and carbon-based nanostructures are studied by using density functional theory combined with non-equilibrium Green's function.The main research contents of this paper are as follows:Firstly,the authors studied the effects of zigzag FeB₂ monolayer nanoribbons with different widths and the termination of iron atoms and boron atoms on the electron transport properties of FeB₂ monolayer nanoribbons,and found that as the edges are terminated by Fe and B,respectively,and the FeB₂ nanoribbons have high spin polarization.It is found that this high spin polarization phenomenon is mainly caused by the symmetry of the dihedral angle distribution composed of the FeB₂ nanoribbons.Secondly,the authors also studied the electron transport properties of carbon-based cyclopropyllithium nanostructures.We found that the cyclopropyllithium derivative molecule[{?-c-CSiMe₃C₂H₄Li]₄ has a significant negative differential resistance effect.In addition,we also explored the effect of doping Ge atoms on the electron transport of cyclopropyllithium derivatives.Through further analysis,it was found that the negative differential resistance effect is an inherent property of cyclopropyllithium derivatives.Finally,the authors also studied the electron transport properties of single and double-layer graphene composite structures.The results show that the sawtooth single-and double-layer graphene nanoribbons composite structures SD-ZGNRs?5,5?and SD-ZGNRs?5,6?exhibit a significant Seebeck effect.It is found that the Seebeck effect of the zigzag single-and double-layer graphene nanoribbon composite structure is mainly caused by he opposite spin transmission peaks on both sides of the Fermi level.