Dresden 2009 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 39: Quantum dots: Optical and transport properties
HL 39.1: Vortrag
Donnerstag, 26. März 2009, 09:30–09:45, BEY 81
Electrical injection of a spin polarized electron into a single quantum dot — •Jie Huang1, Robert Arians1, Jörg Nannen1, Tilmar Kümmell1, Jan Wenisch2, Karl Brunner2, and Gerd Bacher1 — 1Werkstoffe der Elektrotechnik, Universität Duisburg-Essen — 2Experimentelle Physik III, Universität Würzburg
The electrical injection of a carrier with a defined spin into a single quantum dot (SQD) is a fundamental step to electrically driven spin devices. By combining a diluted magnetic semiconductor (ZnMnSe) as a highly effective spin source with InAs quantum dots, we demonstrate a spinpolarized SQD emitter.
The structure is designed as a p-i-n diode with self organized InAs quantum dots embedded into the intrinsic GaAs region and with an n-doped ZnMnSe layer, serving as spin aligner. Nanoapertures in the top contact provide access to SQD emission. The device is placed into a magnetic field in Faraday geometry and biased in forward direction. The spin information can now be extracted directly from the circular polarisation degree of the electroluminescence signal of the SQD, where a spin polarized electron from n-ZnMnSe directly recombines with a hole from p-GaAs. At Ubias=1.45 V, we obtain a spin polarisation of nearly 100 % at T = 5 K. We discuss the reduction of spin polarisation with rising temperature and at higher currents, and the possibility of biexciton formation in the SQDs.