SURFACE-MORPHOLOGY OF INXGA1-XAS/GAAS RELAXED LAYERS CHARACTERIZED BY ATOMIC-FORCE MICROSCOPY

Ga0.65In0.35As layers of a varying nominal epilayer thickness (10 - 1000 nm) have been grown by the MBE technique on GaAs (100) substrates and characterized by the combined use of atomic force microscopy (AFM) and grazing incidence X-ray diffraction (GIXD). The surface roughness and morphology have been investigated. The GIXD and AFM results show that the thinnest films are characterized by an asymmetric strain relaxation along the two ?110? directions with no surface crosshatched pattern but with a misfit dislocation network. AFM images on the thickest films show also well-oriented protrusions along the [110] direction, which increase in size and become more elongated as the nominal film thickness increases.