Impacts of dislocations and point defects on the internal quantum efficiency of the near-band-edge emission in ALGaN-based DUV light-emitting materials

Shigefusa Chichibu, Hideto Miyake, Kazumasa Hiramtsu, Akira Uedono

Research output: Chapter in Book/Report/Conference proceedingChapter

1 Citation (Scopus)

Abstract

In this chapter, we show the impact of point defects rather than threading dislocations (TDs) on the emission dynamics of the near-band-edge (NBE) excitonic luminescence in AlN and high AlN mole fraction (x) AlxGa1 −xN alloy films using deep ultraviolet (DUV) time-resolved luminescence and positron annihilation measurements. The extreme radiative nature of excitons in AlN is identified, as the radiative lifetime (τR) for a free excitonic emission was determined to be as short as 11 ps at 7 K and 180 ps at 300 K, which are the shortest ever reported for the spontaneous emission in bulk semiconductors. However, apparent τR increased to 530 ps at 7 K with increasing impurity and Al-vacancy (VAl) concentrations irrespective of the TD density. The result reflects the contribution of bound exciton components. A continuous decrease in τR with increasing temperature up to 200 K of heavily impurity-doped samples reflects a carrier release from band-tail states. The room temperature (RT) τR of AlxGa1 −xN alloys of high x was nevertheless as short as a few ns at 300 K. The results essentially indicate an excellent radiative performance. Finally, the impact of Si-doping and the resulting cation vacancy formation on the nonradiative lifetime (τNR) of the NBE emission in Al0.6Ga0.4N films are discussed.

Original languageEnglish
Title of host publicationSpringer Series in Materials Science
PublisherSpringer-Verlag
Pages115-136
Number of pages22
DOIs
Publication statusPublished - 2016 Jan 1

Publication series

NameSpringer Series in Materials Science
Volume227
ISSN (Print)0933-033X

ASJC Scopus subject areas

  • Materials Science(all)

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