Berlin 2008 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
HL: Fachverband Halbleiterphysik
HL 16: Quantum dots and wires: Optical properties I
HL 16.12: Vortrag
Montag, 25. Februar 2008, 17:00–17:15, ER 164
Electrical injection and optical probing of spins in a single quantum dot — •Tilmar Kümmell1, Mohsen Ghali1, Robert Arians1, Jan Wenisch2, Karl Brunner2, and Gerd Bacher1 — 1Werkstoffe der Elektrotechnik, Universität Duisburg-Essen, D-47048 Duisburg — 2Experimentelle Physik III, Universität Würzburg, D-97074 Würzburg
In order to use the spin as an information carrier, mechanisms for injection, storage and readout of a single spin are required. We use InAs quantum dots, known for spin relaxation times up to th ms regime, in combination with a diluted magnetic semiconductor (ZnMnSe) that has been proven to be an efficient source of spin polarized carriers. P-i-n-structures allow us to realize both polarized single dot emitters and single spin storage devices.
In the single dot emitter, a spin polarized electron injected from the n-ZnMnSe spin aligner recombines in a single InAs quantum dot with a hole coming from p-GaAs. This results in a significantly polarized electroluminescence from a single quantum dot. Polarization degrees of more than 35% are reached at B=4T, showing an efficient spin injection into the single quantum dot. Similar p-i-n structures are used for electrical charging of a single dot with spin-polarized electrons. Optical probing of a charged single dot using micro-magnetoluminescence exhibits a characteristic polarization pattern of both trionic and excitonic recombination lines. We show that this pattern reflects the polarization of the initially injected electron and can therefore in principle be used for a readout process of a single spin.