Kinetic frustratation of Ostwald ripening in Ge/Si(100) hut ensembles
M.R. McKay, J.A. Venables and J. Drucker
Solid State Communications (2009) in press
Abstract
We show that low area density Ge/Si(100) island ensembles comprised
solely of hut and pyramid clusters do not undergo Ostwald ripening
during days-long growth temperature anneals. In contrast, a very low
density of large, low chemical potential Ge islands reduce the
supersaturation causing the huts and pyramids to ripen. By assuming
that huts lengthen by adding single {105} planes that grow from
apex-to-base, we use a mean-field facet nucleation model to interpret
these experimental observations. We find that each newly completed
plane replenishes the nucleation site at the hut apex and depletes
the Ge supersaturation by a fixed amount. This provides a feedback
mechanism that reduces the island growth rate. As long as the
supersaturation remains high enough to support nucleation of additional
planes on the narrowest hut cluster, Ostwald ripening is suppressed on
an experimental time scale.
Latest version of this document: 18th June 2009.