AVS 45th International Symposium
    Thin Films Division Thursday Sessions
       Session TF-ThA

Paper TF-ThA9
Rutherford Backscattering and Channeling Studies of Al and Mg Diffusion in Iron Oxide Thin Films

Thursday, November 5, 1998, 4:40 pm, Room 310

Session: Ex-situ Characterization of Thin Films
Presenter: S. Thevuthasan, Pacific Northwest National Laboratory
Authors: S. Thevuthasan, Pacific Northwest National Laboratory
W. Jiang, Pacific Northwest National Laboratory
D.E. McCready, Pacific Northwest National Laboratory
S.A. Chambers, Pacific Northwest National Laboratory
N.R. Shivaparan, Montana State University
R.J. Smith, Montana State University
Correspondent: Click to Email
There is growing interest in the epitaxial growth of model oxides on various oxide and metal substrates to obtain high-quality surfaces and films. This interest is being fueled by the utility of these materials in magnetic recording, surface geochemistry, heterogeneous catalysis and integrated microwave devices. A number of single crystal iron oxide films with various stoichiometries and orientations have recently been synthesized in our lab using oxygen-plasma-assisted molecular beam epitaxial growth. In the present work, we have used Rutherford backscattering and channeling techniques to investigate the crystalline quality of epitaxially grown @alpha@-Fe@sub 2@O@sub 3@(0001) on Al@sub 2@O@sub 3@(0001), Fe@sub 3@O@sub 4@(001) on MgO(001), and @gamma@-Fe@sub 2@O@sub 3@(001) on MgO(001). The nature of the film-substrate interface, the crystallographic quality of the films, and Al, Mg, and Fe interdiffusion were investigated. The minimum backscattering yields obtained from channeling and random spectra show that in general the film crystal quality is reasonably good. However, @alpha@-Fe@sub 2@O@sub 3@(0001) grown on Al@sub 2@O@sub 3@(0001) show some disordering at the interface due to the 5.7% lattice mismatch. In contrast, no disorder was seen at the Fe@sub 3@O@sub 4@(001)/MgO(001), and @gamma@-Fe@sub 2@O@sub 3@(001)/MgO(001) interfaces, in keeping with their respective lattice mismatches of -0.36% and -0.89%. Mg appears to outdiffuse into @gamma@-Fe@sub 2@O@sub 3@ film at a lower temperature than that at which Al outdiffusion occurs into epitaxial @alpha@-Fe@sub 2@O@sub 3@. Interestingly, Fe indiffusion was not observed for the @gamma@-Fe@sub 2@O@sub 3@/MgO system until higher temperatures (~800°C) were reached. @FootnoteText@ Work supported by the U.S. Department of Energy, Offices of Basic Energy Sciences and Biological and Environmental Research - Environmental Management Science Program and NSF Grant DMR-9409205