  Germanosilicide thin films are quite different from silicides and germanides.
The germanium composition is not homogeneous, grains have a different shape,
and the substrate is generally strained. This affects grain boundary grooving
and favors agglomeration of germanosilicide films. Our thermodynamics model
shows that the equilibrium Ge composition of germanosilicide films formed on
strained substrates is inhomogeneous and these films are more likely to
agglomerate than those formed on relaxed substrates, in agreement with
experiments. Grain shape too can affect agglomeration: polygonal films, such as
germanosilicides, are more likely to agglomerate than films with rounded grains
(silicides, germanides).
