The effects of surface steps, adatoms, and two-dimensional islands on surface stress of Cu(001) and (111) surfaces were investigated using atomistic simulations. The approach employed to measure surface stresses was thermodynamically rigorous. The simulation results demonstrated that surface steps reduced the surface stress (provided that the step density was not too large), whereas surface adatoms either reduced or increase surface stress depending on the surface orientation. As the surface adatom density increased beyond a coverage of approximately 25%, the surface stress increased but returns to that of the singular surface as the coverage approaches a full monolayer. While it was not possible to create a very large adatom density on the surface (they rapidly combine to form islands), the highest adatom densities will probably occur during low temperature, high-rate growth. Addition of islands onto an otherwise flat surface has little effect on the surface stress. A conceptual basis was provided for understanding the effect of defects upon surface stress in terms of local density ideas. The simulation results were compared with several experimental measurements on the evolution of film stresses during film growth.

Effects of Surface Defects on Surface Stress of Cu(001) and Cu(111). C.W.Pao, D.J.Srolovitz, C.V.Thompson: Physical Review B, 2006, 74[15], 155437 (8pp)