Effect of (2×1) Surface Reconstruction on Elasticity of a Silicon Nano-Plate

A semi-continuum approach is developed to describe the effect of (2×1) surface reconstruction on the elastic modulus of the silicon nano-plate. Young's moduli of a (001) silicon nano-plate along the high-symmetry 100 direction are obtained with and without considering (2×1) surface
reconstruction. The approach predicts that the nano-plate with unreconstructed (001) surface is elastically softer than the bulk while it exhibits the opposite behaviour with (2×1) reconstructed surface. On the (001) surface, the (2×1) reconstructed surface dominates the plate as the thickness of the plate scaling decreases to several tens of nanometre. Whether the nano-plate is softer or stiffer depends on bond loss, bond saturation and direction of bond alignment, which have major impacts on the
mechanics of the nano-plate.