Origin and dynamic properties of major intrinsic nonradiative recombination centers in wide bandgap nitride semiconductors

Shigefusa F. Chichibu, Kohei Shima, Kazunobu Kojima, Shoji Ishibashi, Akira Uedono

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

1 Citation (Scopus)


With respect to (Al,In,Ga)N epilayers and quantum wells, threading dislocations (TDs) have long been believed to as the principal limiting factor for the internal quantum efficiency of the near-band-edge emission. However, the realization of low TD density GaN and AlN substrates and (Al,In,Ga)N layers enabled investigating the roles of point defects and impurities without interferences by TDs, and vacancy-complexes have been revealed to act as origins of major Shockley- Read-Hall (SRH)-type nonradiative recombination centers (NRCs) in GaN. Accordingly, the concentration of NRCs (NNRC) must be decreased in both optical devices and power-switching electronic devices. Here we show the results of positron annihilation and time-resolved luminescence measurements on n- and p-type GaN, AlN, and Al0.6Ga0.4N alloys to reveal the origins of major intrinsic SRH-NRCs and to obtain their capture coefficients for minority carriers. For unintentionally doped and doped n-type GaN, divacancies comprising of a Ga-vacancy (VGa) and a N-vacancy (VN), namely VGaVN, are assigned as major SRH-NRCs with a hole capture-coefficient (Cp) of 6×10-7 cm3s-1. For Mg-doped ptype GaN epilayers grown by metalorganic vapor phase epitaxy (MOVPE), VGa(VN)2 are assigned as major NRCs with electron capture-coefficient (Cn) of 8×10-6 cm3s-1. For Mg-implanted GaN, VGaVN are the dominant NRCs right after implantation, and they agglomerate into (VGaVN)3 clusters with Cn of 5×10-6 cm3s-1 after high-temperature annealing. Since AlN films grown by MOVPE usually contain vacancy-clusters comprising of an Al-vacancy (VAl) such as VAl(VN)2-3, complexes of a cation-vacancy and a few VNs may be the major NRCs in AlN and Al0.6Ga0.4N alloys.

Original languageEnglish
Title of host publicationGallium Nitride Materials and Devices XV
EditorsHiroshi Fujioka, Hadis Morkoc, Ulrich T. Schwarz
ISBN (Electronic)9781510633230
Publication statusPublished - 2020
EventGallium Nitride Materials and Devices XV 2020 - San Francisco, United States
Duration: 2020 Feb 42020 Feb 6

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X


ConferenceGallium Nitride Materials and Devices XV 2020
Country/TerritoryUnited States
CitySan Francisco


  • AlGaN
  • Complex
  • Defect
  • GaN
  • Luminescence dynamics
  • Nonradiative recombination center
  • Vacancy


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