Transmission electron microscopy was used to study the nucleation of ½<110> misfit dislocations in epitaxial ZnTe/GaSb(001) films which had been grown by means of molecular beam epitaxy. By studying films with ZnTe thicknesses which were close to the critical thickness (about 0.2) for the generation of misfit dislocations, it was shown that nucleation occurred at diamond-shaped loops which lay on {111} planes and had 1/3<111> Frank-type Burgers vectors. It was found that these so-called diamond defects, which were of vacancy type, underwent an unfaulting reaction in which a perfect dislocation half-loop was generated on an intersecting {111} slip plane. Observations were made of the unfaulting process during stimulation by an electron beam. When they had been nucleated, subsequent slip and cross-slip of the threading segments of the new half-loop on the inclined {111} planes led to the formation of interfacial ½<110> dislocations in a 60 orientation. It was suggested that the diamond defects arose from a vacancy supersaturation that was produced by reaction at the ZnTe/GaSb interface, and that subsequent unfaulting was driven by the need to reduce the dislocation loop energy.

D.Cherns, S.Mylonas, D.E.Ashenford, B.Lunn: Philosophical Magazine A, 1996, 74[2], 553-68