Spin injection into semiconductors : the role of Fe/Al[sub x]Ga[sub 1-x]As interface
- Michael R.
- Sungkyun
The influence of the growth and post-growth annealing temperatures of Fe/Al{sub x}Ga{sub 1-x}As-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 {approx}5 monolayers of interfacial reactions, and high growth temperatures of 175 C lead to a {approx}9 monolayer thick reacted layer. Polarized neutron reflectivity was used to determine the interfacial magnetic properties of epitaxial Fe{sub 0.5}Co{sub 0.5}/GaAs heterostructures grown under identical conditions. No interfacial magnetic dead layer is detected at the interface for Fe{sub 0.5}Co{sub 0.5} films grown at -15 C, an {approx}6 {angstrom} thick nonmagnetic layer formed at the interface for 95 C growth and an {approx}5 {angstrom} 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/Al{sub x}Ga{sub 1-x}As interface.
- Research Organization:
- Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 977801
- Report Number(s):
- LA-UR-04-5522; TRN: US1003725
- Resource Relation:
- Conference: Submitted to: 2004 International Conference on Indium Phosphide and Related Materials, Kagushima, Japan
- Country of Publication:
- United States
- Language:
- English
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