Propriedades eletrônicas e estruturais de impureza substitucional de silício em nanotubos de BC2N

Abstract

Spin polarized density functional theory (SP-DFT) is used to investigate the incorporation of substitutional Si atoms in the zigzag (5,0) and in the armchair (3,3) BC2N nanotubes (NTs). Our results show that the Si impurities in BC2N NTs have lower formation energy as compared with Si in carbon nanotubes (CNTs) and boron nitride nanotubes (BNNTs). For both nanotubes studied, the Si impurity in the boron site (SiB) show a spin splitting and introduce a empty (spin down) electronic level near to the bottom of the conduction band giving rise to a net spin magnetic moment of 1 μB . Silicon in the nitrogen site (SiN), depending on the tube chirality, introduce electronic levels near or resonant with the top of the valence band leaving the system to exhibit acceptor properties, suggesting the formation of defect induced type-p BC2N NTs. Whereas, for Si in the two non equivalent carbon atoms (SiCI and SiCII), the defective levels are resonant with the valence and conduction bands, respectively. The calculated formation energies for Si impurities in BC2N nanotubos show that the SiCII is the most like defect (lower formation energy). However, when we consider the growth process in the B-rich and N-rich conditions, SiB is the most likely and SiN is the most unlike (higher formation energy) defects.