Regensburg 2010 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 34: Poster I: III-V Semiconductors
HL 34.12: Poster
Dienstag, 23. März 2010, 18:30–20:30, Poster D2
Spin-injection by resonant tunneling of optically excited carriers — •Stefan Oertel1, Jens Hübner1, Dieter Schuh2, Werner Wegscheider2,3, and Michael Oestreich1 — 1Universität Hannover, Institut für Festkörperphysik, Abteilung Nanostrukturen, Appelstr. 2, D-30167 Hannover — 2Universität Regensburg, Institut für Experimentelle und Angewandte Physik, D-93040 Regensburg — 3Now at: Solid State Physics Laboratory, ETH Zürich, Switzerland
High efficient spin injection is a desirable prerequisite for threshold reduction of optically pumped spin VCSELs. The injection wavelength differs in this kind of experiments significantly from the emission wavelength and the maximum spin injection polarization is thereby usually restricted to 50 %. Here we investigate a specially designed spin injection heterostructure based upon resonant tunneling of optically injected spins. The MBE grown (110) GaAs structure consists of a 9 nm QW seperated by 3 nm Al0.36Ga0.64As barriers from two adjacent 4 nm QWs. The resonant excitation of the lowest heavy hole exciton transition of the thin QWs enables the generation of up to 75 % electron spin polarization in the thick QW, which is in our experiment detected by time- and polarization resolved photoluminiscence spectroscopy. The spin injection efficiency and the spin dynamics in the drain QW is investigated in dependence on excitation energy and density.