The growth model and electronic properties of single- and double-walled zigzag silicon nanotubes: Depending on the structures

Highlights: • Pentagons or heptagons play a pivotal role during the simulation of the growth about SiNTs. • The "gearlike" structures of SiNTs are formed by alternating sp² and sp³ hybridization. • All of the zigzag SWSiNTs and DWSiNTs have a narrow band gap. - Abstract: The growth model and electronic properties of the capped zigzag single- and double-walled silicon nanotubes (SWSiNTs and DWSiNTs) are studied with the Density Functional Theory (DFT) method. Particularly, the morphologies of the silicon nanotubes (SiNTs) and the layer-by-layer growth process are explored. Capping of SiNTs is explained well in terms of pentagons. It seems that pentagons or heptagons play apivotal role during the SiNTs growth. Moreover, the structures of the finite SWSiNTs and DWSiNTs are studied. Finally, the infinite SWSiNTs and DWSiNTs can be set up with the repeat unit cells based on the periodic trait of the corresponding finite SiNTs. All of the zigzag SWSiNTs and DWSiNTs have a narrow band gap.