We present scanning tunnelling microscopy results of thin dysprosium silicide films grown on Si(001) 21. At submonolayer coverages, up to 2000 Å long wires are formed in the (110) direction of the Si(001) surface. Depending on Dy exposure and annealing conditions, both wire assemblies and free-standing wires can be grown. At higher coverages, three-dimensional clusters with rectangular shapes are formed.

We present cross-sectional scanning-tunneling microscopy results of threefold stacked InAs quantum dots prepared by metal-organic chemical-vapor deposition at 485 °C and a growth rate of 0.18 nm/s. The dots consist of stoichiometrically pure InAs and show a layer-dependent size. The images indicate a prismatic dot shape with {101} and additional {111} side faces as well as a (001) top face.

We present a detailed cross-sectional scanning-tunneling microscopy investigation of threefold stacked InAs quantum dots in a GaAs matrix grown by metal-organic chemical vapor deposition. The dots are vertically aligned and show a layer-dependent size. Detailed images with atomic resolution indicate that the dots consist of pure InAs with a shape well described by prisms with {110} and additional {111} side faces as well as a (001) top face. The wetting layer is found to be inhomogeneous, while no In diffusion into the overgrowing GaAs layer is observed. These findings demonstrate that growth in the present sample is more related to kinetics than to equilibrium conditions. Furthermore it is demonstrated that the image contrast is strongly influenced by a cleavage-induced outward relaxation of the strained quantum dots.

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Dielectric and optical properties of epitaxial rare-earth scandate films and their crystallization behaviorWe present an investigation of Gd, Dy, Er, and Lu silicides epitaxially grown on n-type Si͑111͒ using scanning-tunneling microscopy, low-energy electron diffraction, and core-level photoemission. With varying silicide film thickness, we observe structurally, electronically, and chemically different silicide phases. In particular we found that the Si-2p photoelectron spectra from monolayer silicides are different from those at higher coverages. This observation is attributed to the structure of the layered hexagonal silicide, with a Si vacancy lattice only present in case of multilayer films. Furthermore, we observe peculiar electronic properties: An extremely low band bending is found in the monolayer range, with a Fermi-level position of only 0.08Ϯ0.05 eV below the conduction-band minimum of silicon, representing the lowest value ever observed on n-type silicon. With increasing coverage, a final Schottky-barrier height of 0.32Ϯ0.05 eV is obtained. This behavior is interpreted as a consequence of the developing metallicity of the silicide overlayer and will be discussed in the framework of theoretical models for Schottky-barrier formation.