Specific misfit dislocation configurations were observed by two-beam dark-field transmission electron microscopy in a system formed by a Ge0.4Si0.6 ultrathin film grown on a (001)Si surface tilted 6° around a <110> axis. An unusual interfacial feature was the presence of triple dislocation nodes linked to ‘Y-centres’ formed by the meeting of two near-60° dislocations and a slightly inclined edge misfit dislocation. It was shown, from the comparison of experimental and computer-aided images, requiring three-dimensional elastic fields of angular dislocations, that some Lomer misfit dislocation terminations were not simply the emerging points of a single dislocation, but very probably linked to two short dislocation legs of threading dislocations in the film.

On Triple Dislocation Nodes Observed by TEM in a Ge0.4Si0.6 Film Grown on a Slightly Deviating (001)Si Substrate. S.Neily, S.Youssef, A.Gutakovskii, R.Bonnet: Philosophical Magazine Letters, 2011,  91[8], 510-5