TY - CHAP
T1 - Impacts of dislocations and point defects on the internal quantum efficiency of the near-band-edge emission in ALGaN-based DUV light-emitting materials
AU - Chichibu, Shigefusa F.
AU - Miyake, Hideto
AU - Hiramtsu, Kazumasa
AU - Uedono, Akira
N1 - Funding Information:
The authors thank Prof. T. Sota of Waseda Univ., Prof. B. Gil of Univ. Montpellier II, Prof. C. Weisbuch of Univ. California Santa Barbara, Dr. M. Tanaka, and Prof. S. Nakamura of Univ. California Santa Barbara for fruitful discussions. The first author is thankful to Dr. K. Furusawa for help with the experiments. This work was supported in part by NEDO programs under METI, Grant-in-Aids for Scientific Research Nos. 23656206 and 18069001 under MEXT, Japan, and AFOSR/AOARD Grant Nos. FA2386-11-1-4013 and FA2386-11-1-4108 monitored by Dr. G. Jessen. We finally thank Prof. Michael Kneissl for giving us a chance to contribute to this issue.
Publisher Copyright:
© Springer International Publishing Switzerland 2016.
PY - 2016/1/1
Y1 - 2016/1/1
N2 - 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.
AB - 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.
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U2 - 10.1007/978-3-319-24100-5_5
DO - 10.1007/978-3-319-24100-5_5
M3 - Chapter
AN - SCOPUS:84947087698
T3 - Springer Series in Materials Science
SP - 115
EP - 136
BT - Springer Series in Materials Science
PB - Springer Verlag
ER -