Berlin 2005 – scientific programme
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HL: Halbleiterphysik
HL 21: Spintronik III
HL 21.5: Talk
Saturday, March 5, 2005, 11:45–12:00, TU P164
Role of carrier lifetime and spin relaxation time for spin injection in an InGaAs detector — •L. Schreiber1, K. Schmalbuch1, N. Müsgens1, B. Beschoten1, G. Güntherodt1, A. Kawaharazuka2, M. Ramsteiner2, J. Herfort2, H.-P. Schönherr2, and K. H. Ploog2 — 12. Physikalisches Institut, RWTH Aachen, 52056 Aachen — 2Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, 10117 Berlin
Spin injection from various ferromagnets into semiconductors through a Schottky barrier was demonstrated by circularly polarized light emitted from a spin LED [1,2]. It turns out that the spin injection efficiencies measured by the degree of optical polarization only weakly depends on the FM injection layer when using InGaAs/GaAs QW as a spin detector. This might be due to its shorter spin relaxation time compared to its carrier lifetime. Therefore, we determine both time constants in an In0.1Ga0.9As/GaAs p-i-n diode by time-resolved transmission and Faraday rotation.
Taking the ratio of both time constants into account as deduced from a rate equation model [1], we find that the injection efficiency at low temperatures (25 K) is a factor of 5 higher than expected from the optical polarization. Approaching 300 K, we observe a steep increase of the correction factor up to a value of 10. A weak dependency on the external bias is found in the range of light emission. BMBF FKZ 01BM160 and 13N8244
[1] M. Ramsteiner, J. Supercond. 16, 661 (03)
[2] A. Kawaharazuka et. al., APL 85, 3492 (04)