Nuclear spin-polarization in single InGaAs quantum dots through electrical and optical spin-injection in spin-LEDs

We investigate nuclear spin polarization in a single InGaAs quantum dot via electrical injection of spinpolarized electrons in a spin‐injection light‐emitting diode. The Overhauser shift in the single‐dot electroluminescence is compared with results obtained for optical spin injection in the same structure. The results clearly demonstrate the possibility of efficient nuclear spin polarization by purely electrical means which might be useful for future spintronic applications. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)