Epitaxial growth of iron oxide films on Ag(1 1 1)

Abstract

Epitaxial iron oxide films are grown on Ag(1 1 1) by two methods. The oxide films are characterized using low-energy electron diffraction, X-ray photoelectron spectroscopy, and X-ray photoelectron diffraction. The first growth method is deposition of Fe films with thickness ranging from 1–10 monolayers on Ag(1 1 1) and oxidizing these films. The Fe film structure prior to oxidation is identified as poorly ordered bcc-Fe(1 1 0), and oxidation leads to the growth of poorly ordered FeO(1 1 1) films. The second method is sequential deposition of sub-monolayer Fe films (typically ⩽0.5 ML) followed by oxidation. This procedure is repeated until the desired oxide film thickness is achieved. Iron oxide films grown by sequential deposition are identified as FeO(1 1 1) for oxide film thickness below ∼10 Å with growth of Fe 3O 4(1 1 1) for thicker films. Iron oxide films grown by the sequential deposition method have much better crystallographic order than those grown by oxidizing thicker iron films. Finally, the surface termination of the Fe 3O 4(1 1 1) films is investigated using X-ray photoelectron diffraction.