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Abstract:

The appearance of a luminescence ring around a central illumination spot in quantum well structures is now well understood in terms of charge separation between the electron and hole gasses in the quantum well region with the ring appearing at their boundary. We propose a slightly modified model including Coulomb interaction between the electron and hole gas and their image charge. © 2005 Elsevier Ltd. All rights reserved.

Abstract:

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 tunneling perpendicular to the QW plane. ©2005 The American Physical Society.