Effect of size dependent surface stress on bending of ultrathin nanofilms

Abstract

Bending of nanofilms with thicknesses down to sub nanometers was addressed. The size dependence of surface stress and elastic modulus were considered in the current bending model. Our model can describes bending of nanofilms with any configuration of surface stress and lattice misfit. Model calculations with physically reasonable parameters fit well with available molecular dynamics simulation. It is found that the size dependence of surface stress is of vital importance on surface stress dominated bending of ultrathin nanofilms. The derived two dimensional Stoney formula shows that the Poisson ratio would have significant effects on the bending of nanofilms under anisotropic surface stress.