MAGNETITE FE3-DELTA-FO4 - A STOICHIOMETRY AND STRUCTURE-ANALYSIS OF MBE GROWN THIN-FILMS USING NO2 AS THE OXIDIZING SOURCE

Epitaxial single crystalline films of iron oxides have been grown on M gO(100) substrates by means of MBE. Natural Fe or Fe-57 was evaporated from alumina crucibles, and oxidised simultaneously with a dosed flux of NO2. The resulting oxide layers have been characterised in situ wi th RHEED, LEED, XPS, and AES. RHEED intensity oscillations, observed d uring deposition of the oxides, indicate a layer-by-layer growth for a ll substrate temperatures between 373 and 673 K. A stoichiometry analy sis with GEMS, performed ex situ: shows that it is straightforward to prepare both the stable magnetite Fe3O4 and the metastable maghemite g amma-Fe2O3 phases. Moreover, also all solid solutions in between these two extreme phases, i.e. Fe3-deltaO4 with 0<delta<1/3, could be forme d. Ion beam channelling has been used to examine the epitaxy of the fi lms. It was found that the films grow coherent on MgO(100).