In-situ IR and RHEED Observations of fcc-Fe Epitaxial Growth on Cu(100) in an Atmosphere of Carbon Monoxide

Infrared reflection absorption spectroscopy (IRRAS) and reflection high-energy electron diffraction (RHEED) have been applied to in-situ observations of fcc-Fe epitaxial growth on Cu(100) at room temperature under very low carbon monoxide (CO) pressures. Extended layer-by-layer growth of fcc-Fe is observed at a CO pressure of 2.7 x 10 - 8 Pa. Nevertheless, no adsorbed CO was detected on the growing film surface. The layer-by-layer growth is hampered severely at a CO pressure higher than 1.3 x 10 - 7 Pa. A small band that is attributable to CO adsorption appears in the IRRAS spectra taken in the early stages of deposition at 1.3 x 10 - 6 Pa. These observations indicate that the dissociation of adsorbed CO on the growing film surface plays an important role in the promotion of the layer-by-layer film growth of fcc-Fe.