Strained-layer superlattices, grown onto GaAs(100) substrates, were studied by using Raman spectroscopy and transmission electron microscopy. It was shown that the interfaces within the superlattice were coherent, but the superlattice/substrate interface contained an orthogonal 2-dimensional network of 60° misfit dislocations. By using these experimental data, values were determined for the plastic strain in individual layers and for the average values of the residual elastic strain in strained-layer superlattices. The latter were about an order of magnitude higher than the theoretically predicted values; thus suggesting that the relaxation of the elastic strains was not complete. Annealing of these structures led to the generation of more misfit dislocations; this was again consistent with further relaxation of the elastic strain.

Study of Strain Relaxation in InAs/GaAs Strained-Layer Superlattices by Raman Spectroscopy and Electron Microscopy. A.K.Gutakovsky, S.M.Pintus, A.I.Toropov, N.T.Moshegov, V.A.Haisler, S.Rubanov, P.Munroe: Australian Journal of Physics, 2000, 53[5], 697-705