Intermixing-promoted scaling of Ge/Si(100) island sizes

The shape evolution and the effect of deposition temperature on size and
composition of chemical vapor deposition grown Ge/Si(100) islands have
been investigated in the deposition temperature range 450–850 °C. It is
found that the increase of the growth temperature above 600 °C entails a
strong island enlargement due to an increased Si/Ge intermixing. The
crystallographic structure of the islands was investigated by transmission
electron microscopy. The analysis of the resulting Moire´ pattern reveals
that the island lattice deformation decreases with increasing island size
and that the effective mismatch e between the silicon substrate and the
epilayer decreases with increasing deposition temperature. The island
nucleation size, the mean size of coherent islands and the critical size
for the insertion of misfit dislocations have been found to scale as e-2,
e-2, and e-1, respectively. The agreement of our experimental scaling
results with the predictions of theoretical calculation performed for
homogeneous heterostructures suggests that, although the Si
distribution inside the islands is not homogeneous, the island growth is
driven by the mean effective strain.