Determination of diffusion energies on face-centred cubic(111) surfaces from diffraction experiments: a Monte Carlo study

The nucleation of adatom islands on face-centred cubic (fcc) (111) surfaces is studied by kinetic Monte Carlo simulations (MCS). The temperature depen dence of the island density follows an Arrhenius behaviour with characteris tic energy E-D/3 (where E-D denotes the diffusion energy on terraces), in a greement with classical nucleation theory for the critical nucleus size of one. The diffuse scattering of the diffraction spots in the submonolayer ra nge shows ring-like structures which are attributed to the characteristic i sland distance, since the ring radius follows an Arrhenius behaviour with c haracteristic energy E-D/6. This energy does not depend on coverage for the submonolayer range investigated (Theta less than or equal to 0.5 ML), whic h implies that the diffusion energy can also be obtained from higher-covera ges where coalescence of islands has already started. The results of these MCS are applied to experimental data of homoepitaxial growth on Pt(111). (C ) 2000 Elsevier Science B.V. All rights reserved.