Absorption and emission in quantum dots: Fermi surface effects of Anderson excitons

R. W. Helmes, M. Sindel, L. Borda, J. Von Delft

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Abstract

Recent experiments measuring the emission of exciton recombination in a self-organized single quantum dot (QD) have revealed that different effects occur when the wetting layer surrounding the QD becomes filled with electrons because the resulting Fermi sea can hybridize with the local electron levels on the dot. Motivated by these experiments, we study an extended Anderson model, which describes a local conduction band level coupled to a Fermi sea, but also includes a local valence band level. We are interested, in particular, in how many-body correlations resulting from the presence of the Fermi sea affect the absorption and emission spectra. Using Wilson's numerical renormalization group method, we calculate the zero-temperature absorption (emission) spectrum of a QD, which starts from (ends up in) a strongly correlated Kondo ground state. We predict two features: First, we find that the spectrum shows a power-law divergence close to the threshold, with an exponent that can be understood by analogy to the well-known x-ray edge absorption problem. Second, the threshold energy ω0-below which no photon is absorbed (above which no photon is emitted)-shows a marked, monotonic shift as a function of the exciton binding energy Uexc.

Original languageEnglish
Article number125301
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume72
Issue number12
DOIs
Publication statusPublished - Sep 15 2005

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ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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