Bandstructures of unstrained and strained silicon nanowire

Energy bandstructures of unstrained and strained [100] silicon nanowires are calculated with nearest neighbor (NN) sp³d⁵s* tight binding model. Square nanowires with four {110} bounding facets of various thicknesses are simulated. It is found that bandgaps of nanowires increase with decreasing the wire thickness. Uniaxial strain effects are accounted for by displacing the silicon atoms and modifying the energy parameters in the tight binding model. The results indicate that both compressive and tensile strains reduce the bandgap and tensile strain reduces the hole effective mass at the valence band edge significantly.