STRAIN-INDUCED CHANGES IN EPITAXIAL LAYER MORPHOLOGY OF HIGHLY STRAINED III V-SEMICONDUCTOR HETEROSTRUCTURES/

We present a study of changes in the layer morphology of symmetrically strained (GaIn)As/ Ga(PAs) superlattices as a function of strain and off-orientation of substrates. The samples were deposited by metal-org anic vapour-phase epitaxy (MOVPE). For samples grown on exactly orient ed (100) GaAs substrates sharp 2-dimensional interfaces are observed u p to a lattice mismatch (DELTAd/d)perpendicular-to = 2.4 . 10(-2). The use of off-oriented (100) substrates leads to a strain induced surfac e roughening (3-dimensional growth mode) and the formation of laterall y ordered thickness modulations during further growth. The surface ste ps due to the substrate off-orientation are regarded as a cause for th is effect. We discuss the structural properties of the samples investi gated by transmission electron microscopy (TEM) and high-resolution X- ray diffraction (XRD) as a function of the strain in the individual la yers for samples grown on (100) GaAs substrates exactly oriented, 2-de grees off towards [110] and 1.7-degrees off towards [011], respectivel y.