Strain relief mechanisms in Ge/Si(100) islands

The shape evolution and the effect of deposition temperature on the strain status of Ge/Si(100) islands have been investigated in the deposition temperature range 450-750 degreesC. The island crystallographic structure was investigated by transmission electron microscopy. The analysis of the Moire patterns reveals that the island lattice deformation and the elastic energy per unit volume stored in the islands decrease with increasing island size in quantitative agreement with theoretical results. Furthermore, we evidenced that the effective mismatch E between the silicon substrate and the island epilayer decreases upon increasing the deposition temperature. This misfit reduction is fully accounted by the amount of SiGe intermixing in the epilayer.