Investigation of strain induced patterning in superlattices by grazing incidence diffraction - comparison of morphological and strain ordering

Symmetrically strained superlattices on off-oriented substrates are studied by x-ray grazing incidence diffraction in order to investigate compositional ordering separately from the related lattice strain correlation depending on the lattice mismatch. Narrow grating rods in strain-insensitive reciprocal space maps indicate a remarkably periodic lateral morphological ordering. Significant differences are observed in strain sensitive maps, where grating rod broadening indicates strain fluctuations. From the inclination of satellite branches in the maps, the direction of interface replication and of strain replication can be determined separately for the strained layer superlattice and for the low strained capping layers.