Relaxation behavior of undoped InxGa1-xP 0.5<x<0.7 grown on GaAs by atomic layer molecular-beam epitaxy

We present a study of the relaxation behavior of compressive InxGa1-xP layers grown by atomic layer molecular-beam epitaxy at T-s=420 degrees C with x=56%+/-3% and n=67%+/-3%. Similar (thickness and composition) InxGa1-xP layers were grown under different growth conditions in order to assess the influence of the stoichiometry of the growth front on the structural properties and the relaxation process of this material system. All InxGa1-xP layers were characterized by double-crystal x-ray diffraction, transmission electron microscopy, and Nomarski interference. Our results show that surface stoichiometry during growth does not affect the relaxation behavior of InxGa1-xP layers but strongly determines their structural characteristics related to composition modulation features which appear in all our InxGa1-xP layers. We have established an empirical relation between residual strain and thickness. This relation makes predictable the residual strain of more complicated structures which can be introduced as buffer layers in lattice-mismatched heteroepitaxial systems. (C) 1996 American Institute of Physics.