Step Flow Model of Radial Growth and Shape Evolution of Semiconductor Nanowires

Abstract

A model of radial growth of vertically aligned nanowires (NW) via formation and propagation of monoatomic steps at nanowire sidewalls is developed. The model allows to describe self-consistently the step dynamics and the axial growth of the NW. It is shown that formation of NWs with an abrupt change of wire diameter and a non-tapered section at the top might be explained by the bunching of sidewall steps due to the presence of a strong sink for adatoms at the NW top. The Ehrlich–Schwoebel barrier for the attachment of adatoms to the descending step favors the step bunching at the beginning of the radial growth and promotes the decay of the bunch at a later time of the NW growth.