Twisted-shape selection of self-assembled Si ⟨100⟩ nanobelts and nanowires

Abstract

Abstract This letter discusses the surface-reconstruction-induced self-twisting behavior of Si〈100〉 nanobelts and nanowires (NWs) with rectangular cross section. Giving a thorough physical interpretation, we explain the reason behind this phenomenon and present a continuum-based model. It is revealed that these structures can self-assemble into both right- and left-handed helicoids depending on their crystal arrangements. More specifically, for NWs with the same number of layers in each of their cross sections directions, two distinct values of torsion angle are possible for each of right- and left-handed twisted morphologies. In conclusion, four modes of torsion can be observed in Si〈100〉 NWs. Furthermore, some atomistic simulations are conducted to substantiate analytical results by utilizing Tersoff’s potential. These results confirm the precision of the analytical discussions and are in good agreement with the continuum model predictions. Finally, the results of Tersoff’s potential are validated by a density functional based tight-binding model.