The dislocation patterns in strain-relaxed compositionally graded SiGe buffer layers, which had been grown onto Si(001) by means of molecular beam epitaxy, were studied by using cross-sectional and plane-view transmission electron microscopy. The results favored high growth temperatures and low gradients, and led to threading dislocation densities in the 105/cm2 range. The transmission electron micrographs also permitted the identification of a novel dislocation multiplication mechanism which was well suited to the particular strain conditions in gradient buffer layers.

M.Hohnisch, H.J.Herzog, F.Schäffler: Journal of Crystal Growth, 1995, 157[1-4], 126-31