Separation of excitonic and electron-hole processes in metal tungstates

V Nagirnyi, M Kirm, A Kotlov, A Lushchik, Leif Jönsson

Research output: Contribution to journalArticlepeer-review

Abstract

Absorption, reflection and emission polarization spectra of CdWO4 crystals have been studied in the region 3.5-30 eV in order to distinguish the excitonic and electron-hole processes in the vicinity of the band gap. The following parameters have been defined from the Urbach tail study at 6-300 K: E-0 = 5 eV, sigma(0) = 0.31, homega = 70 meV (565 cm(-1)). Excitonic processes have been shown to dominate at excitation of tungstate crystals in the lower part of the conduction band. Excitons are formed due to the transitions into the tungstate W5d states hybridized with O6p and possess a very strong tendency for self-trapping. Free electrons and holes can be created at the energies 1-2 eV (depending on the crystal) higher than the bottom of the conduction band due to the transitions into cationic states. (C) 2003 Elsevier Science B.V. All rights reserved.
Original languageEnglish
Pages (from-to)597-603
JournalJournal of Luminescence
Volume102
DOIs
Publication statusPublished - 2003

Subject classification (UKÄ)

  • Subatomic Physics

Free keywords

  • band structure
  • urbach rule
  • tungstates
  • absorption

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