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

Paper MI+SC-FrM10
Electrical Spin Injection from CdCr@sub 2@Se@sub 4@ into AlGaAs/GaAs Spin-LED

Friday, November 7, 2003, 11:20 am, Room 316

Session: Semiconductor Spin Injection
Presenter: G. Kioseoglou, Naval Research Laboratory
Authors: G. Kioseoglou, Naval Research Laboratory
A.T. Hanbicki, Naval Research Laboratory
C.H. Li, Naval Research Laboratory
O.M.J. van 't Erve, Naval Research Laboratory
R. Goswami, Naval Research Laboratory
G. Spanos, Naval Research Laboratory
B.T. Jonker, Naval Research Laboratory
R. Mallory, SUNY at Buffalo
M. Yasar, SUNY at Buffalo
G. Itskos, SUNY at Buffalo
A. Petrou, SUNY at Buffalo
Correspondent: Click to Email
Ferromagnetic semiconductors (FMS) provide an opportunity to control spin dependent behavior and study spin injection and transport in semiconductor heterostructures. Much of the effort has focused on III-Mn-V p-type FMS, where the ferromagnetism is mediated by holes. Since electron transport is the basis for high frequency and low power operation, an n-type FMS grown epitaxially on a device quality substrate is especially attractive. Recent work demonstrated epitaxial growth of n-type CdCr@sub 2@Se@sub 4@, a chalcogenide spinel FMS, on GaAs(001) and GaP(001).@footnote 1@ The measured conduction band offsets indicate a staggered band alignment conducive to electron transport from the CdCr@sub 2@Se@sub 4@ into the AlGaAs.@footnote 2@ We present here spin polarized electron injection from CdCr@sub 2@Se@sub 4@ into an AlGaAs/GaAs LED structure. The circular polarization due to spin injection from the CdCr@sub 2@Se@sub 4@ reaches a maximum value of 6% at B = 0.5T, and mimics the hard axis magnetization determined by SQUID magnetometry measurements. In contrast to previously studied ZnMnSe and Fe contacts in which injection of predominantly m@sub j@ = -1/2 electrons was observed, for CdCr@sub 2@Se@sub 4@ the majority of the injected electrons are in the m@sub j@ = +1/2 state. TEM reveals that the existing interfaces are highly defected, a factor known to limit spin injection.@footnote 3@ Efforts to increase the spin injection efficiency are focused on improving the interface, the contact resistance and electrical properties of CdCr@sub 2@Se@sub 4@. Ga, an n-type dopant in CdCr@sub 2@Se@sub 4@, was introduced in a @delta@-doping configuration, and results on new LED structures with improved electrical characteristics and interface morphology will be presented. @FootnoteText@ This work was supported by DARPA SpinS program, ONR, and NSF. @footnote 1@Y.D. Park et al., Appl. Phys. Lett. 81, 1471 (2002). @footnote 2@H.B. Zhao et al, Appl. Phys. Lett. 82, 1422 (2003). @footnote 3@R. Stroud et al, Phys. Rev. Lett. 89, 166602 (2002).