Multilayered and single-layered structures of self-assembled quantum dots were grown via molecular beam epitaxy, and examined using cross-sectional transmission electron microscopy. Threading dislocations were generated from large incoherent InAs islands, and often appeared in pairs. The dislocations in a given pair had different Burgers vectors and did not form a half-loop. On the basis of observations made under zone-axis illumination conditions, it was deduced that the dislocations originated from the overlap between 2 large islands and that the dislocations were caused by misfit between the relaxed InAs islands and the GaAs layer, and threaded the epilayer on {111} planes.

TEM Observation of Threading Dislocations in InAs Self-Assembled Quantum Dot Structure K.Shiramine, Y.Horisaki, D.Suzuki, S.Itoh, Y.Ebiko, S.Muto, Y.Nakata, N.Yokoyama: Journal of Crystal Growth, 1999, 205[4], 461-6