STRAIN INDUCED MACROSTEPS IN (GaIn)As/Ga(PAs) SUPERLATTICES GROWN ON OFF-ORIENTED GaAs SUBTRATES. C. Giannini, Y. Zhuang, L. Tapfer, T. Marschner, W. Stolz, Centro Nazionale Ricerca e Sviluppo Materiali (PA.S.T.I.S.-C.N.R.SM.), S. S. Appia Km. 712, Brindisi 1-72100, Italy, Wiss. Zentrum für Materialwissenschaften und Fachbereich Physik, Philipps-Universität, D-35032 Marburg, Germany

Symmetrically strained (GaIn)As/Ga(PAs) superlattices grown on off-oriented GaAs substrates by metalorganic vapour phase epitaxy were investigated by x-ray scattering techniques. High-resolution x-ray diffraction measurements and x-ray reciprocal space maps were performed for different off-orientation angles (0deg.[[radical]]4deg.) towards one of the nearest <110> directions. The substrate off-orientation and the strain were found to affect the structural properties of the superlattices inducing surface roughening and, consequently, the generation of laterally ordered macrosteps. The periodically ordered lateral microsteps give rise to a lateral modulation of the layer thickness (ordered interface roughness) and of the lattice strain. The x-ray diffraction measurements allowed us to determine the lateral and vertical periodicity of the superlattices as well as the strain modulation. The distribution and correlation of the roughness across the interfaces was investigated by the specular and non specular scattered intensity curves. Our results show that the morphology of the roughness on the growth surface is greatly influenced by the off-orientation angle. Evidence of anisotropy in the lateral and vertical correlation of the roughness is found.