Transmission electron microscopy of double heterostructures permitted the onset and development of misfit dislocations to be monitored while increasing the strained-layer thickness from sub- to super-critical. It was observed that misfit segments were introduced into threading dislocations when the strained-layer thickness was close to, but below, the critical thickness that was predicted by the Matthews-Blakeslee model. Analysis showed that threading dislocations could glide and form interfacial misfit dislocation segments, even though the critical thickness which was predicted by the Matthews-Blakeslee model had not been reached. It was also observed that the total dislocation density increased slowly, as the layer thickness increased above its critical value, until a sudden increase occurred. It was suggested that the sudden increase in dislocation density was associated with a different mechanism, of misfit dislocation formation, which dominated global relaxation of the structure.

Formation of Misfit Dislocations during Growth of InGaAs/GaAs Strained-Layer Heterostructures X.W.Liu, A.A.Hopgood, B.F.Usher, H.Wang, N.S.Braithwaite: Semiconductor Science and Technology, 1999, 14[12], 1154-60