Periodic surface modulation on thin epitaxial FeSi2 layers on Si(0 0 1)

The morphology and the structure of thin metastable iron disilicide films grown on Si(0 0 1) are studied by scanning tunneling microscopy and X-ray photoelectron diffraction. It is shown that the FeSi2 silicide has a quadratic crystallographic structure, with the c-axis perpendicular to the sample surface. As to the film morphology, the silicide consists of rather flat islands with a √2×√2 R45° surface periodicity for a coverage lower than 4 ML. At a nominal Fe coverage of 4 ML, the silicon surface is almost completely covered. The surface exhibits a quite periodic height modulation of about 2 Å.