Observation of preformed electron-hole Cooper pairs in highly excited ZnO

Marijn A. M. Versteegh, A. J. van Lange, H. T. C. Stoof, and Jaap I. Dijkhuis
Phys. Rev. B 85, 195206 – Published 15 May 2012

Abstract

Electrons and holes in a semiconductor form hydrogen-atom-like bound states, called excitons. At high electron-hole densities the attractive Coulomb force becomes screened and excitons can no longer exist. BCS theory predicts that at such high densities cooperative many-body effects can at low temperatures induce a bound state, an electron-hole Cooper pair, comparable to an electron-electron Cooper pair in a superconductor. Here we report the observation of preformed electron-hole Cooper pairs in a semiconductor. By measuring stimulated emission from a dense electron-hole gas in ZnO, we have explored both the crossover from the electron-hole plasma to the preformed Cooper-pair regime, and the crossover from the exciton to the preformed Cooper-pair regime.

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  • Received 17 November 2011

DOI:https://doi.org/10.1103/PhysRevB.85.195206

©2012 American Physical Society

Authors & Affiliations

Marijn A. M. Versteegh1, A. J. van Lange1, H. T. C. Stoof2, and Jaap I. Dijkhuis1,*

  • 1Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 1, 3584 CC Utrecht, The Netherlands
  • 2Institute for Theoretical Physics, Utrecht University, Leuvenlaan 4, 3584 CE Utrecht, The Netherlands

  • *j.i.dijkhuis@uu.nl

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Vol. 85, Iss. 19 — 15 May 2012

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