Theoretical Studies Of Structural Evolution And Electronic Transport Properties Of One Dimensional Nanomaterials In The Confined Space

Nanowires, as the small dimensional structures available in electronic transmission, are crucial for the function and integration of nanodevices,attracting more and more attention in synthesis and assembly fabrication.The most important thing in studying nanowires is fabricating stable one-dimensional structures. Experimentally, nanowires can be successfully fabricated using nanotube templates as the oxidation of nanowires can be prevented efficiently by the hollow structure in nanotubes;on the simulation side, the utility of nanotubes as templates can provide suitable environment for the growth of nanowires, as well as new means to study phase transition in confined space.Conductance is one of the most important parameters in measuring electronic transport properties of metals and alloys.In recent years, resulting from the discovery of superconducting materials, a number of oxide materials have also become the object of interest in superconductivity research, which greatly enriches the electrical study of materials.Because of micro-size, new questions appear in studying nanomaterials:â…°) whether there is difference between nano and traditional metallic materials in conducting behavior;â…±) what are new characteristics of scattering and moving of electrons in nanostructures;â…²) whether metal-oxide materials have conductive properties on nanoscale. Based on these problems, we studied the electronic properties of Sn, Znic-Oxide and Si-Ge-Sn alloy nanowires in nanotubes.Different kinds of nanowires are obtained in single-walled carbon nanotubes(SWCNT) by molecular dynamic method in the first section.In our calculation, the Sn nanowires form helical and parallel patterns respectively. Both Sn nanowires and nanotubes take on similarly twist and deformation under pressure, and the five-strand nanowire has the highest resistance to compression. The current-voltage curves are shift and sharpened, which result from the change of electrons scattering in deformed nanowires.Geometry optimization method is also well used in studying the growth of zinc-oxide and Si-Ge-Sn alloy nanowires in different nanotubes here. As the radius of nanomould increases, the inset ZnO nanowire transforms from a helical single chain to parallel chains. Due to the quantum size effect, a conductance gap appears in each I-V curve when applied low voltage. After a deep discussion, we find that the width of conductance gap is determined by the gap between the highest occupied molecular orbital and the lowest one.After having an investigation in the electronic transport properties, the conductance is observed to be affected by the doping ratio.The Sn atoms weaken the electronic transmission in alloy nanowires.Once the Sn atom ratio exceeds 10 percent, there is little change in current versus voltage when applied low voltage due to the coulomb blockade effect. Moreover, when the number of Ge, Si and Sn are the same in a alloy nanowire, the coulomb blockade effect is remarkably obviously. Because of the tunneling resonant effect, the conductance peaks based on transmission resonances appears with an increasing bias.Also the number of peaks increases with the inclination of Sn atom doping ratio.