We have used in situ electron microscopy to observe the
nucleation of Ge islands on lithographically patterned Si(001) mesas.
Images were obtained at video rate during chemical vapor deposition of
Ge, using a reflection electron microscopy geometry that allows
nucleation to be observed over large areas. By comparing the kinetics
of nucleation and coarsening on substrates modified by different
annealing conditions, we find that the final island arrangement depends
on the nature of the mesa sidewalls, and we suggest that this may be
due to changes in diffusion of Ge across the nonplanar surface.
