A study was made of Si0.84Ge0.16/Si heterostructures, with various (10 to 300) finite lateral dimensions and layer thicknesses, that had been grown by means of selective low-pressure chemical vapor epitaxy at 700C. In particular, relaxation via the formation of misfit dislocations was studied. It was noted that, in small structures, only nucleation and propagation occurred. Dislocation-dislocation interaction (mainly multiplication) became more and more important in large structures. It was possible to separate the 3 different mechanisms (nucleation, propagation, multiplication) which played a role in relaxation. By analyzing misfit dislocations in the initial stages of relaxation, it was possible to determine the nucleation site density. The activation energy for the heterogeneous nucleation of misfit dislocations was deduced to be 2.8eV.

S.Wickenhäuser, L.Vescan, K.Schmidt, H.Lüth: Applied Physics Letters, 1997, 70[3], 324-6