We show both experimentally and theoretically that the recently observed optically induced in-plane charge separation in quantum well (QW) structures and the exciton ring emission pattern at this charge separation boundary have an extremely long lifetime. The oppositely charged carriers remain separated and provide a reservoir of excitons at their boundary with a persistent emission which lasts hundreds of microseconds (orders of magnitude longer than their recombination time) after the external excitation is removed. This long lifetime is due to an interplay between the slow in-plane carrier diffusion and slow carrier tunnelling perpendicular to the QW plane.
@article{arxiv.cond-mat/0412272,
title = {Dynamics of in-plane charge separation front in 2D electron-hole gas},
author = {Gang Chen and Ronen Rapaport and Steven H. Simon and Loren Pfeiffer and Ken West},
journal= {arXiv preprint arXiv:cond-mat/0412272},
year = {2009}
}