The results were reported of molecular dynamics simulations of structures of pristine silicon nanowires and germanium nanowires with bulk cores oriented along the [110] direction and bounded by the (100) and (110) surfaces in the lateral direction. It was found that the (100) surfaces for both silicon and germanium nanowires underwent 2 x 1 dimerization while the (110) surfaces did not exhibit reconstruction. The direction of the dimer rows was either parallel or perpendicular to the wire axis, depending upon the orientation of the surface dangling bonds. The dimer length for Si was in good agreement with the result obtained using first-principles calculations. However, the geometry of Si dimers belonged to the symmetrical 2 x 1 reconstruction rather than asymmetrical buckled dimers. It was also shown that surface reconstruction of a small nanowire induced significant change in the lattice spacing for the atoms not on the (100) surface, resulting in severe structural distortion of the core of the nanowire.

Surface Reconstruction and Core Distortion of Silicon and Germanium Nanowires. W.Liu, K.Zhang, H.Xiao, L.Meng, J.Li, G.M.Stocks, J.Zhong: Nanotechnology, 2007, 18[21], 215703 (9pp)