DIFFUSION ON STRAINED SURFACES

The change of diffusion kinetics when elastic fields are present is di scussed for diffusion on (001) surfaces of simple cubic, fee and bcc l attices. All particles interact pairwise with a Lennard-Jones potentia l. The simple cubic lattice was stabilized by an anisotropic prefactor . It is found that generically compressive strain enhances diffusion w hereas tensile strain increases the activation barrier. An approximate ly linear dependence of the barrier in a wide range of misfits is foun d. In heteroepitaxy, diffusion on top of large clusters is inhomogeneo us and anisotropic. The kinetics close to edges and centers of islands are remarkably different. In many cases changes of binding energies a re small compared to those of saddle point energies. Thermodynamic arg uments (minimization of free energy) are not appropriate to describe d iffusion on strained surfaces in these cases. (C) 1997 Elsevier Scienc e B.V.