The First Principles Study On Silicon Nanotubes Adsorbed Oxygen Molecule

Silicon nanotubes with comprehensive properties of carbon nanotubes and silicon nanowires may provide a new silicon-based material for the manufacture of nano device. This article studies armchair（5,5） silicon nanotubes and three kinds of armchair（5,5） silicon nanotubes adsorbed oxygen molecule（O₂） system. This article combines theoretical analysis with calculation method based on the density functional theory and uses visualizer module of M-S software the structure models. Pure silicon nanotube and silicon nanotube adsorbed oxygen molecule（O₂） systems are designed and established in this paper. By using the plane wave pseudopotential method（CASTEP） software module, the geometrical structures and their stability, electronic and optical properties are studied. Research shows that the armchair（5,5） structure of silicon nanotubes system is stable.The calculation method and research scheme selected are feasible and reliable. The armchair（5,5） structure of silicon nanotubes system has a narrow band gap semiconductor properties, in which the band gap is only0.474 eV. In the range of 100nm-800 nm wavelength, the optical absorption coefficient of the armchair（5,5） structure of silicon nanotubes is larger and it can be used for preparing visible light-ultraviolet absorption materials. That three armchair-type nanotubes（5,5）-O_2A,（5,5）-O_2B,（5,5）-O_2C system structure are stable, It displays that armchair（5,5） silicon nanotube has the ability of adsorption oxygen molecules, and they have the application value in oxygen adsorption; After oxygen adsorption, The band gap of armchair（5,5）-O_2A 、（5,5）-O_2B 、（5,5）-O_2C structure of silicon nanotube system is 0.337eV、0.384 eV and 0.387 eV. The band gaps have a certain degree of decrease compared with armchair（5,5） structure of silicon nanotubes. They all belong to the narrow direct band gap semiconductor. In the range of0-1000 nm wavelength, the optical absorption coefficient of these system are larger and they can be used for the preparation of visible light-ultraviolet absorption materials and gas sensing materials.