Next, a new
nucleation and growth process happened on the already formed
film, to form oriented grown multilayer.The potential energy at
the edge of the islands is much higher than that at the center, so
ad-atoms deposited on the islands were incorporated within the
island itself. The elastic strain energy on the top parts of islands is
usually much lower than that at the bottom. As a result, the surface
diffusion due to the strong uneven distribution of strain energy,
drives ad-atoms to climb up to the tops of islands, and gives rise to
the rapid radial growth of 3D islands. The adjacent islands blocked
ad-atoms come from planar direction, and caught hold of ad-atoms
deposited from the radial directions. Then the interspaces among
islands form and led to the growth of columnar grains perpendicular
to the glass substrate. Finally, oriented films with different
structures were obtained on the substrate.