THE MOLECULAR-BEAM EPITAXY GROWTH OF INGAAS ON GAAS(100) STUDIED BY INSITU SCANNING TUNNELING MICROSCOPY AND REFLECTION HIGH-ENERGY ELECTRON-DIFFRACTION

In situ real space images and reflection high energy electron diffraction (RHEED) data for the initial stages of molecular beam epitaxy growth of highly strained In(x)Ga1-xAs (0.3 less-than-or-equal-to x less-than-or-equal-to 0.6) on GaAs(100) are reported. RHEED patterns, specular intensity oscillations, and surface lattice constant data are recorded simultaneously during growth. From the RHEED analysis we divide the film evolution into two stages, corresponding to a largely unrelaxed and relaxed surface lattice constant. Scanning tunneling microscopy images of the surface of the film as it appeared during growth reveal that the initial phase has a rippled morphology. With further growth the film evolves to a distinctive three-dimensional island microstructure. Both of these characteristic morphologies are interpreted as manifestations of strain in the growing film.