In situ reflection electron microscopy of Ge island nucleation on mesa structures.

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.