Structures and electronic properties of single-walled silicon nanotubes (6,m) under external electric field by SCC-DFTB calculations

Abstract

In this work, using the self-consistent charge density functional tight-binding(SCC-DFTB) approach, we studied essential properties of SWSiNTs (6,m) and effects of perpendicular electronic field and strengths on electronic properties. After atomic relaxation, the structure of the tube changes obviously and different degrees of warping appear. The wall buckling distance is determined by the distance between outward and inward maximum values of the atom. The deviation of atomic radial displacement obviously affects the amount of atomic charge transfer, which increases with the increase of degree of buckling structure. The three primitive tubes are direct band gap semiconductors, among which the armchair tube has the highest binding energy and the most stable structure. As the applied electric field strength increases, the energy separation between adjacent subbands increases, causing a semiconductor-metal transition. The effect of electric field on the atomic charge redistribution in the tube is positively correlated with the warpage of the tube.