Effect of Adsorbed Oxygen on Initial Growth of Fe on Cu(111)

Abstract

Epitaxial growth mode and morphology of Fe on Cu(111), affected by the pre-adsorbed oxygen in the form of a “29” structure of the Cu(111) surface, were investigated by scanning tunneling microscopy (STM) and reflection high-energy electron diffraction (RHEED). According to RHEED observation, the γ-Fe structure was kept to more than 3 monoatomic layers (ML) and fcc and bcc structures coexisted at 5 ML . In contrast, the RHEED pattern of 1 ML Fe on a clean surface already shows the coexistence of fcc and bcc structures. By STM observation, at about 0.4 ML of Fe on the oxygen absorbed Cu(111) surface, small islands appeared on the surface with a high density instead of decorating the step edges with large islands about 6 ML high for the iron growth on a clean Cu(111) surface. As the surface diffusion was suppressed due to oxygen adsorption, the growth mode was significantly changed. However, no strong surfactant effect was observed as in Fe growth on oxygen-adsorbed Cu(001) surface where the γ-Fe structure was kept to 45 ML with a surface O (\\sqrt2×\\sqrt2)R45° reconstruction and all the oxygen floated to the surface.