Optical absorption in degenerately doped semiconductors: Mott transition or Mahan excitons?

André Schleife, Claudia Rödl, Frank Fuchs, Karsten Hannewald, Friedhelm Bechstedt

Research output: Contribution to journalArticle


Electron doping turns semiconductors conductive even when they have wide fundamental band gaps. The degenerate electron gas in the lowest conduction-band states, e.g., of a transparent conducting oxide, drastically modifies the Coulomb interaction between the electrons and, hence, the optical properties close to the absorption edge. We describe these effects by developing an ab initio technique which captures also the Pauli blocking and the Fermi-edge singularity at the optical-absorption onset, that occur in addition to quasiparticle and excitonic effects. We answer the question whether free carriers induce an excitonic Mott transition or trigger the evolution of Wannier-Mott excitons into Mahan excitons. The prototypical n-type zinc oxide is studied as an example.

Original languageEnglish (US)
Article number236405
JournalPhysical review letters
Issue number23
StatePublished - Nov 30 2011
Externally publishedYes

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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