Origin of the spontaneous orientational ordering of islands during thin film growth

Abstract

The spontaneous orientational order of some metal islands on Cu(001) along 〈100〉 has long eluded its explanation, which is now revealed by the study with the kinetic Monte Carlo simulation. The orientational order originates from the relative stability of the diagonal orientation of the neighboring islands against their coalescence. That stability results from the square symmetry of the islands, since the diagonally meeting islands have the minimum contact area mediating their merge. Moreover, we well reproduce and elucidate the orientational order propagating into the following several tens of monolayers. The orientational order of the islands is driven simply by the symmetry of the surface unit cell and is thus generic in the epitaxial growth, making pervasive effects on the physical properties of the epitaxial films.