XRD Investigation of the relaxation of InAsP layers grown by CBE on (100) InP

We present X-ray diffraction (XRD) investigations of the influence of the substrate off-orientation on the relaxation of InAsP layers grown on InP by chemical beam epitaxy (CBE). Our measurements show that with beginning relaxation the As-concentration increases drastically and stays constant if the relaxation degree is further increased. The increase in with beginning relaxation does not depend on the substrate off-orientation, although decreases with increasing off-orientation for pseudomorphic structures. XRD measurements on (partly) relaxed samples show different relaxation degrees in [0 1 1] and [0 1] directions. The dependence of the asymmetry of the relaxation in different directions on the substrate off-orientation and the layer thickness is discussed with respect to the influence of surface steps on the generation of misfit dislocations.