Electrical spin injection from ZnMnSe into InGaAs quantum wells and quantum dots

We report on efficient injection of electron spins into InGaAs-based nanostructures. The spin light-emitting diodes incorporate an InGaAs quantum well or quantum dots, respectively, as well as a semimagnetic ZnMnSe spin-aligner layer. We show a circular polarization degree of up to 35% for the electroluminescence from InGaAs quantum wells and up to 21% for InGaAs quantum dots. We can clearly attribute the polarization of the emitted photons to the spin alignment in the semimagnetic layer by comparison to results from reference devices (where the ZnMnSe is replaced by ZnSe) and from all-optical measurements.