In an examination of the chemical structures of the AlOx Co90 Fe10 interface, we confirmed that thermal treatment affects the redistribution of oxygen at the interface and that this leads to an increase in the tunneling barrier height of magnetic tunnel junctions. The as-deposited Al oxide barrier with a thickness of ~13 Å was oxygen-deficient AlOx, but most of it turned into Al2 O3, the thermodynamically stable stoichiometric phase, through annealing. This enrichment of oxygen is likely responsible for the observed improvement. The near-edge x-ray absorption fine structure spectra of Co and Fe proved the fact that after bonding with Co and Fe in the underlying CoFe layer, the oxygen diffused back into the barrier and thereby enriched the barrier to the point where it mostly consisted of Al2 O3. Our results confirm that controlling the chemical structures at the interface is a key to modify the properties of magnetic tunnel junctions.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)