The size dependence of elastic modulus of ZnO nanofilms is investigated by using atomistic simulations. The strain energy and elastic stiffness of the surface and interior atomic layers, as well as interlayer interactions, are decoupled. The surface stiffness is found to be much lower than that of the interior layers and bulk counterpart, and with the decrease of film thickness, the residual tension-stiffened interior atomic layers are the main contributions of the increased elastic modulus of nanofilms.

• Received 8 January 2007

DOI:https://doi.org/10.1103/PhysRevB.76.165407