AVS 49th International Symposium
    Electronic Materials and Devices Monday Sessions
       Session EL+SC+MI-MoA

Paper EL+SC+MI-MoA3
Characterization of an Fe/AlGaAs Tunnel Barrier Interface for Electrical Spin Injection

Monday, November 4, 2002, 2:40 pm, Room C-107

Session: Metal-Semiconductor Interfaces
Presenter: R.M. Stroud, Naval Research Laboratory
Authors: A.T. Hanbicki, Naval Research Laboratory
R.M. Stroud, Naval Research Laboratory
B.T. Jonker, Naval Research Laboratory
Correspondent: Click to Email
Electrical injection of spin-polarized carriers from a contact into a semiconductor is essential for the success of spintronic devices. Ferromagnetic metals are attractive contact materials because of their ample supply of spin-polarized electrons, but the use of these materials has been limited by small injection efficiencies in the diffusive transport regime.@footnote 1@ The use of a tunnel barrier between a metal and semiconductor.however. should facilitate usable spin currents.@footnote 2@ Recent experiments reported spin injection from Fe into a AlGaAs/GaAs-based LED which produced an electron spin polarization of 15% in the GaAs quantum.@footnote 3@ This was attributed to tunneling through the Schottky barrier. We have characterized the Fe/AlGaAs contact reported in reference 3 to verify the tunneling nature of the contact and to investigate the physical nature of the interface. Samples were grown by molecular beam epitaxy and were specifically engineered to utilize the Schottky barrier between the Fe and the semiconductor as a tunnel contact. Current vs voltage measurements were made through the structure at different temperatures. The conductance shows an asymmetric parabolic dependence on the voltage. Further, there is a weak insulating-like behavior of the zero-bias resistance as a function of temperature, a reliable indication that this is a tunneling process based on the Rowell criteria for tunneling.@footnote 4@ High-resolution TEM measurements indicate an atomically abrupt interface between the metal and semiconductor. Current-in-plane measurements and the relation of bias voltage to spin polarization will also be discussed. This work was supported by the DARPA SpinS program and ONR. @FootnoteText@ @footnote 1@G. Schmidt, et al, Phys.Rev.B 62, R4790 (2000)@footnote 2@E.I. Rashba, Phys.Rev.B 62, R16267 (2000)@footnote 3@A.T. Hanbicki, et al., Appl.Phys.Lett. 80, 1240 (2002)@footnote 4@B.J. Jönsson-Åkerman, et al., Appl.Phys.Lett. 77, (2000).