AVS 47th International Symposium
    Magnetic Interfaces and Nanostructures Wednesday Sessions
       Session MI+EL-WeM

Paper MI+EL-WeM3
Demonstration of Electrical Spin Injection: The Spin-LED@footnote 1@

Wednesday, October 4, 2000, 9:00 am, Room 206

Session: Magnetic Semiconductors and Hybrid Structures I
Presenter: Y.D. Park, Naval Research Laboratory
Authors: Y.D. Park, Naval Research Laboratory
B.R. Bennett, Naval Research Laboratory
B.T. Jonker, Naval Research Laboratory
H.-D. Cheong, SUNY, Buffalo
G. Kioseoglou, SUNY, Buffalo
A. Petrou, SUNY, Buffalo
Correspondent: Click to Email
Electrical spin injection into a semiconductor is a prerequisite for realizing the potential of semiconductor-based spintronic devices. This has been an elusive goal, however, and only modest effects (@<=@ 1%) have been obtained. We report here highly efficient electrical spin injection from a magnetic contact into a GaAs quantum well-based light emitting diode (LED) heterostructure (a spin-LED@footnote 2,3@) in which the spin injection efficiency exceeds 50%. Radiative recombination of spin polarized carriers in quantum wells results in the emission of circularly polarized light. The degree of optical polarization is proportional to the carrier spin polarization, enabling a direct, quantitative measure of the spin injection efficiency. The samples consist of ZnSe/ZnMnSe/AlGaAs/GaAs/AlGaAs heterostructures grown by MBE on p-GaAs(001) substrates, where the semimagnetic semiconductor ZnMnSe serves as a source of spin-polarized electrons which are injected via an applied bias voltage into the GaAs quantum well. Standard optical lithography and chemical etch procedures were used to define surface emitting LED mesa structures. The measured circular polarization of the electroluminescence (EL) exceeds 50%, and demonstrates that highly efficient spin transport occurs across the ZnMnSe/AlGaAs interface despite the large 0.5% lattice mismatch. Data are reported as a function of injection current, magnetic field, and temperature. The EL lineshape consists of multiple components whose relative polarization provide insight into spin relaxation mechanisms. We compare results from ex situ and in situ contacts, and with those obtained for carefully lattice matched systems.@footnote 4@. @FootnoteText@ @footnote 1@ This work was supported by the Office of Naval Research. @footnote 2@ US patent #5,874,749 (filed 6/93; awarded 2/99) @footnote 3@ Jonker, et al., submitted for publication. @footnote 4@ Fiederling, et al., Nature 402, 787 (16 December 1999).