Decay of pyramidal nano-island formed on Si(1 0 0) studied by kinetic Monte Carlo simulation

By using kinetic Monte Carlo simulation based on a modified solid-on-solid model, the decay process of pyramidal nanostructure island formed on Si(1 0 0) surface is studied. The decay proceeds primarily due to mass transport of atoms on the surface from a kink or a step edge site of the island to another step edge in the lower layer. The basic process is the same for both two- and three-dimensional (3D) islands. The decay rate of the 3D island is, however, larger than that of the two-dimensional (2D) island by a factor of 2–4. The difference is attributed to different distance from the starting step edge to the terminating one. The diffusion length in the case of 2D island decay is much smaller than that estimated by the terrace length of the underlying layer. The diffusion occurs through atom vacancies formed on the terrace in the underlying layer. The vacancy-mediated diffusion is an important process for the decay of 2D island.