Analysis of below-threshold efficiency characteristics of InGaN-based blue laser diodes

In this study, we investigate the below-threshold emission characteristics of InGaN-based blue laser diodes (LDs) emitting at 442 nm to study the efficiency droop effects in InGaN LDs. From the measurement of spontaneous emission in the LD, it is observed that the peak efficiency appears at a curren...

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Bibliographic Details
Published in:Journal of applied physics 2012-10, Vol.112 (8)
Main Authors: Ryu, Han-Youl, Jun Choi, Won, Jeon, Ki-Seong, Kang, Min-Goo, Choi, Yunho, Lee, Jeong-Soo
Format: Article
Language:English
Subjects:
Augers
Current density
Density
Indium gallium nitrides
Laser diodes
Quantum efficiency
Recombination coefficient
Spontaneous emission
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Summary:In this study, we investigate the below-threshold emission characteristics of InGaN-based blue laser diodes (LDs) emitting at 442 nm to study the efficiency droop effects in InGaN LDs. From the measurement of spontaneous emission in the LD, it is observed that the peak efficiency appears at a current density of ∼20 A/cm2 and the efficiency at the threshold current density of ∼2.3 kA/cm2 are reduced to ∼47% of the peak efficiency. The measured spontaneous emission characteristics are analyzed using the carrier rate equation model, and the peak internal quantum efficiency is found to be ∼75% using the fit of the measured efficiency curve. In addition, the Auger recombination coefficient of the measured InGaN blue LD is found to be 10−31–10−30 cm6/s, which is somewhat lower than that reported for InGaN-based blue light-emitting diodes. It is discussed that low dislocation density and uniform current injection in quantum wells may have resulted in the low Auger recombination coefficient of InGaN LDs.
ISSN:0021-8979
1089-7550
DOI:10.1063/1.4759247