Oscillator strength reduction induced by external electric fields in self-assembled quantum dots and rings

We have carried out continuous wave and time resolved photoluminescence experiments in self-assembled In(Ga)As quantum dots and quantum rings embedded in field effect structure devices. In both kinds of nanostructures, we find a noticeable increase of the exciton radiative lifetime with the external voltage bias that must be attributed to the field-induced polarizability of the confined electron hole pair. The interplay between the exciton radiative recombination and the electronic carrier tunneling in the presence of a stationary electric field is therefore investigated and compared with a numerical calculation based on the effective mass approximation.
The authors gratefully acknowledge financial support by the Spanish MEC and CAM through Projects Nos.TEC-2005-05781-C03-01/03, NAN2004-09109-C04-01/03,CSD2006-0019, and S-505/ESP/000200, and by the European Commission through the SANDIE Network of Excellence (Contract No. NMP4-CT-2004-500101).