Tuning the valence and concentration of europium and luminescence centers in GaN through co-doping and defect association

Khang Hoang
Phys. Rev. Materials 5, 034601 – Published 4 March 2021
PDFHTMLExport Citation

Abstract

Defect physics of europium (Eu) doped GaN is investigated using first-principles hybrid density-functional defect calculations. This includes the interaction between the rare-earth dopant and native point defects (Ga and N vacancies) and other impurities (O, Si, C, H, and Mg) unintentionally present or intentionally incorporated into the host material. While the trivalent Eu3+ ion is often found to be predominant when Eu is incorporated at the Ga site in wurtzite GaN, the divalent Eu2+ is also stable and found to be predominant in a small range of Fermi-level values in the band-gap region. The Eu2+/Eu3+ ratio can be tuned by tuning the position of the Fermi level and through defect association. We find co-doping with oxygen can facilitate the incorporation of Eu into the lattice. The unassociated EuGa is an electrically and optically active defect center and its behavior is profoundly impacted by local defect-defect interaction. Defect complexes such as EuGaON, EuGaSiGa, EuGaHi, EuGaMgGa, and EuGaONMgGa can efficiently act as deep carrier traps and mediate energy transfer from the host into the Eu3+4f-electron core which then leads to sharp red intra-f luminescence. Eu-related defects can also give rise to defect-to-band luminescence. The unassociated EuGa, for example, is identified as a possible source of the broad blue emission observed in n-type, Eu2+-containing GaN. This work calls for a re-assessment of certain assumptions regarding specific defect configurations previously made for Eu-doped GaN and further investigation into the origin of the photoluminescence hysteresis observed in (Eu,Mg)-doped samples.

  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
4 More
  • Received 9 September 2020
  • Accepted 24 February 2021

DOI:https://doi.org/10.1103/PhysRevMaterials.5.034601

©2021 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Khang Hoang*

  • Center for Computationally Assisted Science and Technology & Department of Physics, North Dakota State University, Fargo, North Dakota 58108, United States

  • *khang.hoang@ndsu.edu

Article Text (Subscription Required)

Click to Expand

Supplemental Material (Subscription Required)

Click to Expand

References (Subscription Required)

Click to Expand
Issue

Vol. 5, Iss. 3 — March 2021

Reuse & Permissions
Access Options
Author publication services for translation and copyediting assistance advertisement

Authorization Required


×
×

Images

×

Sign up to receive regular email alerts from Physical Review Materials

Log In

Cancel
×

Search


Article Lookup

Paste a citation or DOI

Enter a citation
×