M. Kanoun, R. Benabderrahmane, C. Duluard, C. Baraduc, N. Bruyant, A. Bsiesy,

Carrier transport mechanism across tunnel dielectric barrier separating a ferromagnet from silicon is an important issue for spin-polarised electrons injection into non magnetic semiconductors. Direct tunnelling of electrons between the ferromagnet and the silicon energy bands is a prerequisite for spin conservation through the barrier. We showed that depending on the nature of the barrier, transport mechanism can take place either through a defect assisted tunnelling as in the case of silicon dioxide, or through direct tunnelling as in the case of aluminium oxide. These results show that although silicon dioxide is the best established dielectric barrier on silicon for electronic applications, it may not be suitable for building spintronic devices on silicon. Future work will be focused on aluminium oxide tunnel barriers