Formation of self-assembled heteroepitaxial islands in elastically anisotropic films

The formation of self-assembled heteroepitaxial islands in elastically anisotropic cubic films is investigated by a three-dimensional dynamic method. In the formulation, the (100) film surfaces evolve through surface diffusion driven by the gradient of the surface chemical potential. Our simulations reveal that when the elastic anisotropic strength A [A is defined as (formula presented) where (formula presented) (formula presented) and (formula presented) are elastic constants] is larger than 1 the formed islands are preferentially aligned along 〈100〉 directions, while when A is smaller than 1 the formed islands are preferentially aligned along the 〈110〉 directions. It is found that the stronger the elastic anisotropy, the stronger the island self-assembly. In addition, the island alignment and averaged island spacing right after island formation are found to be related to the smallest fastest surface instability wavelength of the elastically anisotropic films.