Recent research has demonstrated the effectiveness of the so-called aspect ratio trapping technique for eliminating threading dislocations in Ge grown selectively in sub-micron trenches on Si substrates. Here, an analysis of the mechanisms by which dislocation elimination was achieved was carried out. Detailed transmission electron microscopy studies reveal that facets, when formed early in the growth process, played a dominant role in determining the configurations of threading dislocations in the films. These dislocations were shown to behave as “growth dislocations,” which were replicated during growth approximately along the facet normal and so were deflected out from the centre of the selective epitaxial regions.

Study of the Defect Elimination Mechanisms in Aspect Ratio Trapping Ge Growth. J.Bai, J.S.Park, Z.Cheng, M.Curtin, B.Adekore, M.Carroll, A.Lochtefeld: M.Dudley: Applied Physics Letters, 2007, 90[10], 101902