AVS 55th International Symposium & Exhibition
    Magnetic Interfaces and Nanostructures Thursday Sessions
       Session MI-ThM

Paper MI-ThM9
Electrical Spin Injection into InAs Wetting Layer

Thursday, October 23, 2008, 10:40 am, Room 206

Session: Magnetic Surfaces, Interfaces, Thin Films and Heterostructures
Presenter: C.H. Li, Naval Research Laboratory
Authors: C.H. Li, Naval Research Laboratory
G. Kioseoglou, Naval Research Laboratory
A.T. Hanbicki, Naval Research Laboratory
R. Goswami, Naval Research Laboratory
C.S. Hellberg, Naval Research Laboratory
B.T. Jonker, Naval Research Laboratory
M. Yasar, SUNY Buffalo
A. Petrou, SUNY Buffalo
Correspondent: Click to Email

Efficient electrical injection of spin-polarized electrons from a magnetic contact into a semiconductor is an essential requirement for utilizing the spin degree of freedom in semiconductor spintronic devices. InAs is an attractive material for optoelectronic and high-speed transistor devices due to its small bandgap and high electron mobility. Owing to its large Rashba spin-orbit coupling, the 2-dimensional electron gas (2DEG) formed in InAs-based heterostructures has also been proposed for spin transport within a spin field effect transistor (FET).1 Here we demonstrate efficient spin injection from Fe into a thin (~3ML) InAs wetting layer (WL) that forms on GaAs before the formation of InAs quantum dots (QDs).2 Cross sectional scanning tunneling microscopy (STM) and transmission electron microscopy (TEM) show that the WL is continuous laterally over many microns, and that it is an intermixed InxGa1-xAs layer. Transport measurements reveal a 2DEG-like behavior. The WL electroluminescence is readily distinguished from that of the QDs, and dominates emission at higher biases over a wide temperature range up to RT. We measure an optical circular polarization of 26% at 5K due to the injection of spin-polarized electrons from a reverse-biased Fe Schottky contact, which corresponds to an electron spin polarization >50% after lifetime corrections, demonstrating that even this remarkably thin layer supports high spin polarization. This polarization stayed relatively constant up to 60K, and decreased to ~6% at room temperature, consistent with the D’yakonov-Perel spin relaxation mechanism which dominates at high temperatures.

Work at NRL are supported by ONR and NRL core funds. Work at SUNY are supported by NSF.
1S. Datta and B. Das, Appl. Phys. Lett. 56, 665 (1990).
2C. H. Li et al. APL 91, 262504 (2007).