Berlin 2008 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
HL: Fachverband Halbleiterphysik
HL 17: Poster I
HL 17.14: Poster
Montag, 25. Februar 2008, 16:30–19:00, Poster D
Influence of sulfur on the polarization degree in spin-injection light-emitting diodes with lattice-matched ZnMnSSe spin aligners — •Jens Müller, Wolfgang Löffler, Benedikt Westenfelder, Heinz Kalt, Dongzhi Hu, Daniel M. Schaadt, and Michael Hetterich — Institut für Angewandte Physik, Universität Karlsruhe (TH), 76128 Karlsruhe, Germany
We investigate the spin alignment of electrons in ZnMnSSe-based alloys and their subsequent injection into InGaAs quantum dots using spin-injection light-emitting diodes (spin-LEDs). Due to the antiferromagnetic coupling of neighbored Mn spins in ZnMn(S)Se one finds a maximum effective Mn concentration for xMn∼ 14%. However, the maximum giant Zeeman splitting occurs for xMn∼ 9%, apparently due to a strong increase of the effective temperature Teff with manganese content. To further improve the achieved spin injection efficiency in spin-LEDs we grew ZnMnSSe aligner layers lattice-matched to GaAs. Because of poorer crystal quality in the resulting quaternary alloys, magneto-PL measurements show lower spin-polarization with increasing sulfur content. At the same time we found a dramatic increase in the intra-Mn photoluminescence at about 2.1 eV. This increase is thought to originate from localization effects of excitons that lead to Auger-like transitions within manganese atoms. The maximum circular polarization degree achieved in InGaAs quantum dot ensemble measurements of lattice-matched spin-LED structures was in the order of 70%.