AVS 46th International Symposium
    Magnetic Interfaces and Nanostructures Technical Group Wednesday Sessions
       Session MI+EM-WeM

Paper MI+EM-WeM10
Electrical Spin Injection into LED Heterostructures

Wednesday, October 27, 1999, 11:20 am, Room 618/619

Session: Spin-Dependent Tunneling and Transport
Presenter: B.T. Jonker, Naval Research Laboratory
Authors: B.T. Jonker, Naval Research Laboratory
B.R. Bennett, Naval Research Laboratory
G. Kioseoglou, State University of New York, Buffalo
A. Petrou, State University of New York, Buffalo
Correspondent: Click to Email
Optical excitation has routinely been used to create spin polarized carrier populations in semiconductor heterostructures. Surprisingly long spin lifetimes and diffusion lengths have been reported in optically pumped GaAs in studies which have addressed both semi-classical@footnote 1@ and quantum coherent regimes.@footnote 2,3@ It is very desirable to electrically inject spin polarized carriers via a ferromagnetic contact to increase the potential for practical applications. This has been an elusive goal, however, and only modest effects (@<=@ 1%) have been obtained.@footnote 4@ In an effort to investigate the efficiency of electrical spin injection into semiconductors, we have fabricated light emitting diode structures with ferromagnetic contacts. The radiative recombination of spin polarized carriers in quantum wells results in the emission of circularly polarized light, with the degree of optical polarization directly proportional to the carrier spin polarization. The samples consist of FM / InAs / AlSb / GaSb / AlSb heterostructures grown by MBE on p-GaAs(001) substrates in which the GaSb quantum well serves as the active region for radiative recombination. Standard optical lithography and chemical etch procedures were used to define mesa structures with transparent surface contacts. Measurements are performed as a function of injection current, magnetic field, and temperature. We compare results from ex situ contacts with those obtained from samples for which the ferromagnetic films are deposited in situ via MBE. @FootnoteText@ @footnote *@ This work was supported by the Office of Naval Research. @footnote 1@ D. Hagele, M. Oestreich, W.W. Ruhle, N. Nestle and K. Eberl, APL 73, 1580 (1998). @footnote 2@ A.P. Heberle, W.W. Ruhle and K. Ploog, PRL 72, 3887 (1994). @footnote 3@ J.M. Kikkawa and D.D. Awschalom, PRL 80, 4313 (1998); Nature 397, 139 (1999). @footnote 4@ Y.Q. Jia, R.C. Shi and S.Y. Chou, IEEE Trans. Magnetics 32, 4707 (1996).