The evolution of the shape and size distributions of Ge islands on Si(001)
during annealing after deposition has been studied at different temperature
s and effective coverages. The initial distributions of square-based pyrami
ds, elongated "hut'' structures, faceted "dome- shaped'' islands, and much
larger "superdomes'' depends on the deposition conditions. During annealing
after deposition, the islands coarsen over a limited range of times and te
mperatures. Those pyramidal-shaped islands that grow transform to faceted,
dome-shaped islands as they become larger. Initially dome-shaped islands th
at dissolve transform to a pyramidal shape as they become smaller during th
e process of dissolving. Outside of this coarsening regime, the islands can
achieve a relatively stable, steady-state configuration, especially at low
er temperatures. At higher temperatures, intermixing of Si into the Ge isla
nds dominates, decreasing the strain energy and allowing larger islands to
form. At lower and intermediate temperatures, the initial wetting layer is
metastable, and some Ge transfers to the islands during the early stages of
annealing. (C) 1999 American Institute of Physics. [S0021-8979(99)02702-4]
.