Electronic Properties Of Single-wall Carbon Nanotubes

Carbon nanotubes composed of carbon atoms can be considered approximately as one-dimensional systems with nanostructures, which have singular and abundant physical capabilities. Electronic properties of single-wall carbon nanotubes are much popular on the subjects of material, physics, chemistry, micro-electronics and energy at the present time.In this thesis, we study the density of electronic states of single-wall carbon nanotubes. The effects of tube-diameters and chiralities on the electronic structures are discussed by means of the analytical expression of band structures of single-wall carbon nanotubes under the consideration of curvature effects. It is shown that the curvature effects make an important role on the electronic structures of single-wall carbon nanotubes due to the fact that the electronic structures contact tightly with geometrical structures. After considering the curvature effects, we find that armchair tubes are yet metallic with no band gaps. As for metallic zigzag tubes and metallic chiral tubes, a curvature-induced band gap and two accessional von Hove singularities can be found. The width of the band gap depends on its tube-diameter and chirality. In addition, the peak of von Hove singularity splits. And the width of the peak splitting is determined by its chirality. The energy position of main von Hove singularity contacts with its tube-diameter and chirality. Moreover, the band gaps of semiconductor tubes are inversely proportional to their tube-diameters. The energy position of main von Hove singularity contacts with its tube-diameter and chirality.Based on the band structures, we study the electronic effective masses of single-wall carbon nanotubes. Our studies indicate that geometrical structures have very important effects on electronic effective masses of single-wall carbon nanotubes. We find that therelations between the electronic effective mass of lowest-lying conduction band and wave vector are resemble, not only for narrow-gap semiconductor zigzag tubes but also for wide-gap semiconductor zigzag tubes. The electronic effective masses at bottom of lowest-lying conduction band depend on their tube-diameters. Again, the electronic effective masses at bottom of lowest-lying conduction band of narrow-gap semiconductor zigzag tubes are inversely proportional to square of their tube-diameters. As for chiral tubes, the electronic effective masses at bottom of lowest-lying conduction band contact with their tube-diameters and chiralities.Furthermore, we discuss the application of molecular dynamics method on heat transport of single-wall carbon nanotubes.The thesis is organized as following: In the part of introduction, we roughly describe the background and the purpose of the study. In chapter 1, the basic characters of single-wall carbon nanotubes are briefly introduced. In chapter 2, we mainly describe the fundamental theories about molecular dynamics method and transfer matrix method. In chapter 3, after introducing the curvature-modified electronic structures of single-wall carbon nanotubes, we study the density of electronic states. The relations between the electronic structures and tube-diameters and chiralities are discussed. In chapter 4, we study the electronic effective masses of single-wall carbon nanotubes by using band structures of them. In chapter 5, we study the heat transport of single-wall carbon nanotubes by using molecular dynamics method. In last chapter, our results are summarized briefly.