Direct Observation of the Mott Transition in an Optically Excited Semiconductor Quantum Well

L. Kappei, J. Szczytko, F. Morier-Genoud, and B. Deveaud
Phys. Rev. Lett. 94, 147403 – Published 15 April 2005

Abstract

We have studied density-dependent time-resolved photoluminescence from a 80 Å InGaAs/GaAs single quantum well excited by picosecond pulses. We succeed in giving evidence for the transition from an exciton-dominated population to an unbound electron-hole pair population as the pair density increases. For pair densities below this excitonic Mott transition we observe a spectrally separate emission from free electron-hole pairs in addition to excitonic luminescence, thereby proving the coexistence of both species. Exciton binding energy and band gap remain unchanged even near the upper bound of this coexistence region. Above the Mott density we observe a purely exponential high energy tail of the photoluminescence and a redshift of the band gap with pair density. The transition occurs gradually between 1×1010 and 1×1011cm2 at the carrier temperatures of our experiment.

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  • Received 22 July 2004

DOI:https://doi.org/10.1103/PhysRevLett.94.147403

©2005 American Physical Society

Authors & Affiliations

L. Kappei, J. Szczytko, F. Morier-Genoud, and B. Deveaud

  • Ecole Polytechnique Fédérale de Lausanne, EPFL, CH-1015 Lausanne, Switzerland

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Issue

Vol. 94, Iss. 14 — 15 April 2005

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