AVS 50th International Symposium
    Magnetic Interfaces and Nanostructures Thursday Sessions
       Session MI+SC-ThM

Invited Paper MI+SC-ThM1
Materials for Spin Injection Into GaN-Based Devices

Thursday, November 6, 2003, 8:20 am, Room 316

Session: New Spintronic Materials
Presenter: C.R. Abernathy, University of Florida
Authors: C.R. Abernathy, University of Florida
G.T. Thaler, University of Florida
R.M. Frazier, University of Florida
A. Stewart, University of Florida
S.J. Pearton, University of Florida
F. Ren, University of Florida
Y.D. Park, Seoul National University, Korea
R. Rairigh, University of Florida
J. Kelly, University of Florida
J. Lee, Seoul National University, Korea
A.F. Hebard, University of Florida
Correspondent: Click to Email
Future spintronic devices will likely require injection of polarized currents into semiconductor devices. Though significant work has been carried out in GaAs-based materials, the rapid advancement of GaN-based devices for visible light emission and high power electronics makes this an attractive system for investigation. Two types of spin injection layers appear most promising. One approach is to incorporate magnetic ions into the semiconductor. The introduction of Mn into GaN has been shown to produce ferromagnetism at 300K, making it one of the few DMS materials which may be technologically useful. This method may be limited by the relatively low degree of ordering and the possibility of scattering at the DMS/semiconductor interface. An alternative approach is the use of ferromagnetic layers with metallic conduction, such as MnAs. This material has been used to produce polarized injection into GaAs-based structures, though only at low temperature. Though the lattice mismatch to GaN is greater than for GaAs, the MnAs crystal structure possesses the same Group V symmetry as GaN. This may make growth of a good quality MnAs/GaN interface more achievable than for the MnAs/GaAs heterostructure. This talk will discuss the growth and characterization of both of these types of spin injection layers on GaN. Gas-source molecular beam epitaxy using either an RF nitrogen plasma source, for GaMnN, or AsH3, for MnAs, along with elemental sources for Ga and Mn have been used to deposit thin films on MOCVD GaN buffer layers. Conditions for depositing single phase material with optimum magnetic ordering will be described. The processing challenges associated with integrating these materials into standard GaN/AlGaN light emitting diodes (LEDs) will be discussed along with preliminary electroluminescence results from SpinLEDs fabricated using only low temperature processing. This work was supported by the U. S. Army Research Office (ARO-DAAD19-01-1-0701) and NSF (ECS-0224203).