Structural Stability and Electronic Properties of InAs Nanowires and Nanotubes: Effects of Surface and Size

Abstract

The surface and size effects on the structural stability and electronic properties of InAs one-dimensional nanostructures are investigated by first-principles calculations within density functional theory. No matter what the diameters, the nanowires are more energetically favorable than the nanotubes due to the preferable sp3 hybridization for In and As atoms in the InAs nanostructures. The formation energies of these nanostructures satisfy a linear dependence relationship with the surface atom ratio. The calculated band structures reveal that the band gaps of InAs nanostructures are determined by two competition mechanisms. One is the quantum confinement effect, which favors the increase of the band gaps with the decreasing diameter or wall thickness. Another is the effect of surface dangling bonds, which induces the decrease of the band gaps with the decreasing diameter or wall thickness. With the same diameter, the band gaps of InAs nanowires are still less than those of the nanotubes. The result indicates that the quantum confinement effect in one-dimensional structures can be enhanced by the formation of tubes instead of wires.