Self-diffusion dynamics processes relevant to 2D homoepitaxy growth of Ni adatom on Ni(111) surface

Using molecular dynamics and modified analytic embedded atom methods, the atomic self-diffusion dynamics behaviors relevant to 2D crystal growth on Ni(111) surface have been studied between 150 and 600 K. On perfect Ni(111) surface, the activation energy and prefactor are 0.058±0.001 eV and 4.2×10−4 cm2/s between 150 and 350 K, and 0.082±0.003 eV and 7.8×10−4 cm2/s from 400 to 600 K. Ni adatom just hops along the directions of close-packed steps on stepped Ni(111) surface, the corresponding activation energies and prefactors are 0.188±0.002 eV and (3.8–4.4)×10−3 cm2/s along the direction of A-type step, 0.140±0.001 eV and (1.1–1.2)×10−3 cm2/s along the direction of B-type step, and both fitting lines of Arrhenius law intersect at Tc=420–440 K. Our results show that the atomic growth dynamics under nonequilibrium conditions is gradually dominated by the prefactor with increasing temperature. In addition, the shape-change of the 2D nanometer-size island has been discussed on stepped Ni(111) surface in different temperature range.