SPECTROSCOPIC STUDIES OF THE THERMAL MODIFICATION OF THE FE/AL2O3 INTERFACE

A combination of high resolution electron energy loss spectroscopy (HREELS) and Auger electron spectroscopy (AES) has been applied to the investigation of thin metallic iron films on Al2O3. Two thermally-activated processes have been observed at the Fe/Al2O3 interface. In the temperature region 90-400 K, agglomeration of iron occurs to produce larger clusters of iron (process I). In the temperature region 400-900 K, little change is observed in the thin film, except for some enhancement of the elastic scattering of 3.8 eV electrons, and some small changes in Auger intensity. Above ∼ 900 K, diffusion of the iron into the Al2O3 film occurs, resulting in the production of a clean Al2O3 surface by 1200 K. (process II). It has been demonstrated that the diffusion of metallic iron into Al2O3 is not accompanied by oxidation of iron. In addition to the study of the Fe/Al2O3 interface, it was found that an iron oxide film on Al2O3 does not agglomerate into clusters below ∼ 900 K, but that iron oxide diffusion into Al2O3 occurs above ∼ 900 K. © 1990.