Evolution of self-assembled Ge/Si island grown by ion beam sputtering deposition

► The Ge/Si islands were prepared by ion beam sputtering deposition. ► The intermixing led to the reappearance of low aspect ratio islands. ► Short islands did not grow along the constant ratio of 11:1 (diameter:height). ► The islands always grew faster in the vertical direction. ► The inter-diffusion, surface diffusion and amount of Ge determined the evolution.