Interface formation of iron on In-terminated InAs(001)

In situ scanning tunneling microscopy (STM) is used to investigate the nucleation and initial growth of iron on InAs(001) (4×2)/c(8×2) at room temperature and at 200 °C. Sequences of STM frames show the development at a specific location in the different stages of interface formation. At room temperature, initially 0.5 monolayer of iron grows in the form of small anisotropic clusters, which form long chains along [110] induced by the InAs substrate reconstruction. Further growth proceeds with the formation of isotropic 3d islands, resulting in a granular overlayer at higher coverages. Coalescence of the individual grains is strongly suppressed. At 200 °C the anisotropic chain structure is absent, but rectangular islands grow from the beginning. A decomposition of the substrate indicates intermixing. Room-temperature deposition followed by annealing at 200 °C leads to closed iron layers that are interspersed with pinholes, allowing diffusion of substrate material to the surface .