Interface properties of iron oxide films

We have investigated in a systematic way the interface properties of Fe2O3 grown on different buffer layers using an electron beam deposition technique. For films deposited directly onto Si(001) substrate and on Al buffer layer, we observed the presence of metallic Fe at the Si(001) and Al interfaces, respectively. We also detected the presence of SiO2 and Al2O3 by x-ray photoelectron spectroscopy. For Fe2O3 films deposited on Cu buffer layer, however, no other phases were observed at the interface. We explain our results using the enthalpy of formation. The enthalpy of formation of SiO2 and Al2O3 is much lower than that of Fe2O3, thus inhibiting the crystalline growth of Fe2O3 at the interface. The enthalpy of formation of CuO is, however, greater than that of Fe2O3, and thus promoting the growth of Fe2O3 to be crystalline. These results were corroborated by our transmission electron microscopy studies.