Structural Transition in Large-Lattice-Mismatch Heteroepitaxy

The mechanisms of island nucleation, growth, and dislocation formation in large-lattice-mismatch heteroepitaxy is analyzed theoretically. It is shown that 2D platelets tend to transform to 3D islands as they exceed a certain critical size. During island growth, the increase of the strain concentration at the island edge makes it increasingly difficult for adatoms to reach the island, which leads to the formation of homogeneously sized islands. The high strain concentration at the island edge is eventually relieved by growing in of misfit dislocations. copyright 1996 The American Physical Society