Nucleation and growth of Fe on GaAs(001)-(2×4) studied by scanning tunneling microscopy

The nucleation and growth of Fe on GaAs(001)-(2×{}4) has been studied in situ with scanning tunneling microscopy. The growth is dominated by the structure of the substrate reconstruction. Fe initially forms stable six- to eight-atom two-dimensional islands confined to the first-layer As-dimer rows. The islands preferentially coalesce along the rows, leading to an anisotropic film morphology that persists for at least the first 50 {} of growth. These results provide insight into the growth mode of Fe on GaAs surfaces and have implications for the magnetic properties of ultrathin Fe films.