Regensburg 2010 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 55: Quantum Dots and Wires, Optical Properties IV: Spin
HL 55.4: Vortrag
Donnerstag, 25. März 2010, 14:45–15:00, H14
Electrical spin injection and ultrafast charging of single InAs quantum dots — •Jörg Nannen1, Tilmar Kümmell1, Jan Wenisch2, Karl Brunner2, and Gerd Bacher1 — 1Werkstoffe der Elektrotechnik & CeNIDE, Universität Duisburg-Essen, Bismarckstr. 81, 47057 Duisburg — 2Experimentelle Physik III, Universität Würzburg, Am Hubland, 97074 Würzburg
Single quantum dots (SQD's) are highly interesting candidates for future spin-based devices, which utilize electron spins as information carriers. Due to spin relaxation times up to the ms regime, self-assembled InAs quantum dots are ideal model systems to establish concepts to inject, store and read-out the spin information of single electrons.
We use an all-electrical approach to charge single InAs quantum dots embedded in a p-i-n-diode structure with a single electron. Using micro-photoluminescence spectroscopy, an abrupt switching between the neutral exciton and the negatively charged exciton can be observed. In combination with a diluted magnetic semiconductor (ZnMnSe) as a spin-aligner it is possible to electrically inject spin-polarized electrons with polarization degrees of more than 40 % [1]. An all-optical read-out scheme is demonstrated, which is independent from the injection process and does not destroy the spin information of the injected electron. To use this approach for future spin-based devices, electrical control of the charge state of the SQD's must be accomplished in the GHz-range. By high-frequency adaptation of the sample setups we are able to demonstrate electrical charging of the SQD's in less than 2 ns.
[1] Ghali et al., Appl. Phys. Lett. 93, 073107 (2008)