AVS 50th International Symposium
    Magnetic Interfaces and Nanostructures Friday Sessions
       Session MI+SC-FrM

Invited Paper MI+SC-FrM7
Efficient Electrical Spin Injection in GaAs: A Comparison Between Different Spin Sources

Friday, November 7, 2003, 10:20 am, Room 316

Session: Semiconductor Spin Injection
Presenter: P. Van Dorpe, IMEC, Belgium
Authors: P. Van Dorpe, IMEC, Belgium
V.F. Motsnyi, IMEC, Belgium
Z. Liu, IMEC, Belgium
W. Van Roy, IMEC, Belgium
G. Borghs, IMEC, Belgium
J. De Boeck, IMEC, Belgium
Correspondent: Click to Email
Electrical spin injection in semiconductors remained elusive for a long time. Recently however, break-throughs have been accomplished in the field. It appeared that tunnel injection of spin polarized electrons from ferromagnetic metals provides an efficient way for spin injection, even at room temperature. We will quantitatively compare different spin sources for spin injection in GaAs, based on tunnel injection from ferromagnetic materials. The injected spin polarization is assessed in a (Al,Ga)As-based spin-LED, using the Oblique Hanle Effect@footnote 1@ as the analysis technique. The first material combination that we successfully applied for spin injection is a CoFe/AlOx based tunnel injector where the AlOx provides a stable tunnel barrier between the ferromagnetic material and the GaAs. We have shown injected spin polarizations which exceed 24% at 80K and 12% at room temperature.@footnote 2@ A second spin source we examined uses the native Schottky barrier between GaAs and an epitaxially grown ferromagnetic metal as tunnel barrier. NiMnSb, MnAs and MnSb have been used and will be compared for their spin injection properties. Finally the results of electron spin injection from a (Ga,Mn)As-based Zener diode will be discussed. The spin polarized holes in (Ga,Mn)As are transferred to electrons in GaAs by Zener tunnelling and create a spin polarization in GaAs of at least 50% at LHe temperature. The results on electrical spin injection regularly show an interesting dependence on the applied bias. This dependence will be shown and discussed in terms of doping and band structure. @FootnoteText@@footnote 1@V.F. Motsnyi et al, Appl. Phys. Lett. 81, 265 (2002) @footnote 2@P. Van Dorpe et al, Jpn. J. Appl. Phys., Part 2 42, L502 (2003) Acknowledgements : SPINOSA (IST-2001-33334), FENIKS(GR5D-CT-2001-00535).