Spin dynamics and level structure of quantum-dot quantum wells

Jesse Berezovsky, Min Ouyang, Florian Meier, David D. Awschalom, David Battaglia, Xiaogang Peng

Published 2004-11-08, updated 2005-12-03Version 2

We have characterized CdS/CdSe/CdS quantum-dot quantum wells using time-resolved Faraday rotation (TRFR). The spin dynamics show that the electron g-factor varies as a function of quantum well width and the transverse spin lifetime of several nano-seconds is robust up to room temperature. As a function of probe energy, the amplitude of the TRFR signal shows pronounced resonances, which allow one to identify individual exciton transitions. While the TRFR data are inconsistent with the conduction and valence band level scheme of spherical quantum-dot quantum wells, a model in which broken spherical symmetry is taken into account captures the essential features.