GROWTH, STRUCTURE AND MORPHOLOGY OF ULTRATHIN IRON FILMS ON CU(100)

Growth, structure and morphology of ultrathin iron films deposited at 300 K on Cu(100) were investigated by LEED (low-energy electron diffraction), MEED (medium-energy electron diffraction) and AES (Auger electron spectroscopy). Three regions of coverage with different growth characteristics could be distinguished. The growth in the first region up to about 5 ML (monolayers) is characterized by iron agglomeration. At around 5 ML the islands coalesce and the growth mode changes to layer-by-layer growth. The formation of misfit dislocations leads to the breakdown of epitaxial growth at around 14 ML. This picture is confirmed by diffusion experiments. The diffusion processes are strongly influenced by the structure and morphology of the iron films. At low coverages three different superstructures evolve with increasing film thickness. These are a (4 x 1) at around 2 ML, a (5 x 1) around 4 ML and a (2 x 1) between 6 and 7 ML.