Spin injection into semiconductors: The role of the Fe/AxGa 1-xAs interface

C. Adelmann, B. D. Schultz, J. Strand, X. Lou, X. Y. Dong, J. Q. Xie, S. Park, M. R. Fitzsimmons, P. A. Crowell, C. J. Palmstrøm

Research output: Chapter in Book/Report/Conference proceedingConference contribution

9 Scopus citations

Abstract

The influence of the growth and post-growth annealing temperatures of Fe/AlxGa1-xAs-based spin light-emitting diodes (LEDs) on the spin injection efficiency is discussed. The extent of interfacial reactions during molecular beam epitaxial growth of Fe on GaAs was determined from in-situ x-ray photoelectron spectroscopy studies. The Fe/GaAs interface results in ≤ 3 monolayers of reaction for Fe grown at -15°C. Intermediate growth temperatures (95°C) lead to ∼5 monolayers of interfacial reactions, and high growth temperatures of 175°C lead to a ∼9 monolayer thick reacted layer. Polarized neutron reflectivity was used to determine the interfacial magnetic properties of epitaxial Fe0.5Co0.5/GaAs heterostructures grown under identical conditions. No interfacial magnetic dead layer is detected at the interface for Fe0.5Co0.5 films grown at -15°C, a ∼6 Å thick nonmagnetic layer formed at the interface for 95°C growth and a ∼5 Å thick magnetic interfacial reacted layer formed for growth at 175°C. Spin injection from Fe contacts into spin LEDs decreases sharply when reactions result in a nonmagnetic interfacial layer. Significant spin injection signals are obtained from Fe contacts grown between -5°C and 175°C, although the higher Fe growth temperatures resulted in a change in the sign of the spin polarization. Post-growth annealing of the spin LEDs is found to increase spin injection efficiency for low Fe growth temperatures and to a sign reversal of the spin polarization for high growth temperature (175°C). An effective Schottky barrier height increase indicates that post growth annealing modifies the Fe/AlxGa1-xAs interface.

Original languageEnglish (US)
Title of host publicationConference Proceedings - International Conference on Indium Phosphide and Related Materials
Pages505-510
Number of pages6
StatePublished - 2004
Event2004 International Conference on Indium Phosphide and Related Materials, 16th IPRM - Kagoshima, Japan
Duration: May 31 2004Jun 4 2004

Other

Other2004 International Conference on Indium Phosphide and Related Materials, 16th IPRM
CountryJapan
CityKagoshima
Period5/31/046/4/04

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