Crystal-field analysis of photoluminescence from orthorhombic Eu centers and energy transfer from host to Eu in GaN co-doped with Mg and Eu

Mitsuo Yamaga, Akhilesh K. Singh, Douglas Cameron, Paul R. Edwards, Katharina Lorenz, Menno J. Kappers, Michal Boćkowski

Research output: Contribution to journalArticlepeer-review

Abstract

Gallium nitride co-doped with magnesium and europium shows great potential for active layers in red light emitting diode structures due to strong and sharp luminescence emission around 620 nm. In this work, sharp and intense Eu3+ luminescence lines from the excited states of the 5DJ (J=0, 1) multiplets to the ground states of the 7FJ (J=0, 1, 2) multiplets have been analyzed using a C2v crystal-field equivalent operator Hamiltonian. A model of Eu centers with the C2v symmetry has been proposed to be an Eu3+ complex accompanied by either a pair of nitrogen and gallium vacancies (VN-VGa) or a pair consisting of a nitrogen vacancy and magnesium impurity (VN-MgGa) in the vicinity of the Eu ion based on the crystal-field analysis, the selection rules and the observed polarization of the Eu3+ luminescence lines. Energy transfer from the host to the Eu ions under band-to-band excitation occurs through electron-hole recombination between VN with the electron-like state and VGa or MgGawith the hole-like state; these may be associated with the shallow-trapped or deep-trapped states, respectively, proposed as the energy transfer mechanism in previous literature.
Original languageEnglish
Article number120557
Number of pages36
JournalJournal of Luminescence
Volume270
Early online date19 Mar 2024
DOIs
Publication statusE-pub ahead of print - 19 Mar 2024

Keywords

  • gallium nitride
  • europium
  • orthorhombic center
  • crystal-field analysis
  • energy transfer

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