Figure 5

Growth model of Ge islands on the nanotip pre-patterned Si substrate: (a) Ge atoms were deposited onto the Si nanotips and planar region, (b) some Ge atoms diffuse laterally to the corresponding nanotips on Si substrate, where the strain energy is relatively low, and then form GeSi islands. At the same time, other Ge atoms diffuse vertically into the Si substrates, (c) the composition gradient and layer structure of GeSi islands formed on the Si core.