Theoretical Study Of Electronic And Transport Properties Of Phenyl Covalent Functional Carbon Nanotubes

Carbon nanotubes(CNTs) with excellent electrical properties and optical properties, has become a hot topic in the studied field of international new materials, and widely used in gas storage, biological sensing, nanoelectronic devices, electrode materials. In this paper, the geometry, the band structure and transport properties of pure CNTs and phenyl covalent functional CNTs systems are discussed using firstprinciples density functional theory and non-equilibrium Green's function method, which provide theoretical foundation for studying new conductive materials.(1) We calculated band structure, density of states, and wave function of pure carbon nanotubes and phenyl covalent functional CNTs using SIESTA software based on the density functional theory, in order to study the influence of bonded ways and nanotube diameter to conductivity by comparing the four different bonded ways-direct, amide, cyclohexene and pyrrolidine. The study show that bonded ways and diameters are two factors which affect band structures of functional carbon nanotubes. For zigzag CNT(8,0), a-CNT(8,0)-p and b-CNT(8,0)-p have better electrical properties. For armchair CNT(5,5), c-CNT(5,5)-1 and d-CNT(5,5)-2 are good ways. For zigzag CNT(16,0), c-CNT(16,0)-1 and d-CNT(16,0)-1 have better electrical properties. For armchair CNT(10,10), d-CNT(10,10)-2 has smaller band gap.(2) We calculated volt-ampere characteristic curve and transmission spectrum of pure CNT(8,0), CNT(5,5) and functional carbon nanotubes two probe systems under zero bias in order to study possible of design electronic devices using nanomaterials. Transport properties results show that compared with I-V curves and transmission spectrum between CNT(8,0) and four kinds of phenyl covalent functional CNTs(8,0) two probe systems, we can found both CNT(8,0) and four phenyl covalent functional systems show semiconductor properties, and b-CNT(8,0) has the strongest conductive properties, the current reach to 44.88?A under 2.0V bias voltage. And the I-V curves of functional CNTs by four kinds of bonded ways are very closely to that of pure CNT(5,5) at bias voltage-2.0V~2.0V, and show the similar conductivity properties with pure CNT(5,5).