Efficient spin injection in self‐assembled CdSe quantum dots coupled with a diluted magnetic semiconductor quantum well

Abstract

AbstractElectron‐spin injection has been studied from a diluted magnetic semiconductor quantum well (DMS‐QW) of Zn1–x–yCdxMnySe into self‐assembled quantum dots (QDs) of CdSe through a tunneling barrier of ZnSe. The spin injection is experimentally evidenced by time‐resolved circularly polarized photoluminescence (PL) in the QDs with the circular polarization degree up to 40%. The fast injection time of 20 ps can be attributed to the tunneling probability of the electron from the DMS‐QW side. In addition to this, circularly polarized PL with the lifetime of 3.5 ns is simultaneously observed, indicating type‐II transition between the electron in the QDs and the spin‐polarized heavy hole in the DMS‐QW. Those PL energies directly indicate that the electron tunneling is assisted by a LO phonon in the CdSe QD. The spin injection via LO‐phonon‐assisted resonant electron tunneling provides an efficient spin‐injection process into the self‐assembled QD exhibiting strong quantum confinement effects. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)