Characterization of interfacial reactions in magnetite tunnel junctions with transmission electron microscopy

To make a uniform AlOx barrier layer in tunnel junctions, a thin layer of Al is often sputtered first and then oxidized. In this study, we sputtered a thick layer of Al onto Fe3O4 and then employed high resolution transmission electron microscopy and x-ray energy dispersive spectroscopy to investigate the interfacial microstructures. Two new layers have been found and investigated at the Al/Fe3O4 interface. The interfacial reaction has been determined to be: Fe3O4+Al-->Fe+(a)AlOx, where a denotes the amorphous state. The consequence of the interfacial reaction to transport properties is also discussed. (C) 2004 American Institute of Physics.