Surface diffusion coefficient determination by uniaxial tensile strain in Pb/Cu(111) surface systems

Abstract

Atomic-scale investigations on the surface diffusions of Pb adatoms on uniaxially strained Cu(111) were performed using molecular dynamics simulations and ab initio calculations methods. Tensile strains in [1 (1) over bar0] reduced the surface diffusion coefficient, while the [112] strains increased the diffusion coefficient until the Cu(111) substrate was elongated 4% uniaxially. The surface diffusion energy barriers for the three different paths: [1 (1) over bar0], [112] and [2 (1) over bar1], were calculated using ab initio calculations. The energy barrier only for the [1 (1) over bar0] direction was increased when tensile strain in the [1 (1) over bar0] direction was applied, while the [112] strain decreased the energy barriers for all three diffusion paths. The [1 (1) over bar0] strain altered the easy surface diffusion direction from the x-direction to the y-direction, while the [2 (1) over bar1] strain created isotropic diffusion coefficients in lateral directions.