Strained substrates, composition inhomogeneities, grain shape and the agglomeration of germanosilicide thin films

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).