GISAXS characterization of Ge islands on Si(1Â 0Â 0) substrates

We present a preliminary study of Ge island formation on Si(1 0 0) substrates using grazing-incidence small-angle X-ray scattering (GISAXS). Samples were prepared by high-vacuum evaporation of a 5 nm thick Ge layer on Si(1 0 0) substrate held at 200 °C. The samples were subsequently annealed at different temperatures for 1 h in vacuum, yielding to island formation. The Fortran program IsGISAXS was used for the simulation and analysis of Ge islands. The vertical cut (perpendicular to the surface) of the experimental 2D GISAXS pattern has been fitted using a Guinier approximation. The obtained parameters were used for the simulations. The simulated 2D GISAXS pattern well reproduce experimental data for cylindrically shaped islands with morphological parameters R=4nm, H/R=0.25 and the average inter-island distance D=5nm.