Relaxation processes, in InAsP/InGaAsP strained-layer superlattices with interfacial misfit dislocations, were investigated by means of transmission electron microscopy and X-ray analysis. The transmission electron microscopic results revealed that dislocations were located just within the buffer layer; near to the interface between the buffer and the first well layer in the strained-layer superlattice. An X-ray analysis of the (400) azimuthal angle dependence indicated that the buffer layer had a large macroscopic tilt. The residual strain was determined quantitatively by using reciprocal lattice mapping and a curve-fitting analysis of various (hkl) X-ray profiles for the strained-layer superlattice and buffer layer. These results revealed that the dislocations led mainly to a lattice distortion of the buffer layer, rather than relaxation of the strained-layer superlattice layer. An interesing result was that the changes in the residual perpendicular and parallel strains in the buffer layer were not equal. This strongly suggested that microplastic domains were generated in the buffer layer.

K.Nakashima, H.Sugiura: Journal of Applied Physics, 1997, 82[4], 1599-607