Stability and electronic confinement of free-standingInPnanowires:Ab initiocalculations

Abstract

Using ab initio calculations within the density functional theory we investigate the stability and the electronic confinement of free-standing $\mathrm{InP}$ nanowires, grown along the [111] direction, as a function of the diameter $(d)$. We have found a small reduction of the cohesive energy for wires with diameters smaller than $5\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$, compared to the bulk value. Even for very thin wires the cohesive energy diminishes only a few percents. Also, we verified that, for $d\ensuremath{\sim}2\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$, the energy gap enhancement scales as $1∕{d}^{2}$. However, for a very small diameter $(d\ensuremath{\sim}1.3\phantom{\rule{0.3em}{0ex}}\mathrm{nm})$, this scaling is no longer valid. Concerning the electronic properties, we show that the top of the valence band level, as well as the bottom of the conduction band one are mainly localized in the central region of the wires.