Thermophysical characterization of efficiency droop in gan-based light-emitting diodes

Tzer En Nee, Jen Cheng Wang, Bo Yan Zhong, Jui Ju Hsiao, Ya Fen Wu*

*Corresponding author for this work

Research output: Contribution to journalJournal Article peer-review

4 Scopus citations


An efficiency droop in GaN-based light-emitting diodes (LED) was characterized by examining its general thermophysical parameters. An effective suppression of emission degra-dation afforded by the introduction of InGaN/GaN heterobarrier structures in the active region was attributable to an increase in the capture cross-section ratios. The Debye temperatures and the electron–phonon interaction coupling coefficients were obtained from temperature-dependent current-voltage measurements of InGaN/GaN multiple-quantum-well LEDs over a temperature range from 20 to 300 K. It was found that the Debye temperature of the LEDs was modulated by the InN molar fraction in the heterobarriers. As far as the phonons involved in the electron–phonon scattering process are concerned, the average number of phonons decreases with the Debye tem-perature, and the electron–phonon interaction coupling coefficients phenomenologically reflect the nonradiative transition rates. We can use the characteristic ratio of the Debye temperature to the coupling coefficient (DCR) to assess the efficiency droop phenomenon. Our investigation showed that DCR is correlated to quantum efficiency (QE). The light emission results exhibited the high and low QEs to be represented by the high and low DCRs associated with low and high injection currents, respectively. The DCR can be envisioned as a thermophysical marker of LED performance, not only for efficiency droop characterization but also for heterodevice structure optimization.

Original languageEnglish
Article number1449
Issue number6
StatePublished - 06 2021

Bibliographical note

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© 2021 by the authors. Licensee MDPI, Basel, Switzerland.


  • Debye temperature
  • Efficiency droop
  • Electron–phonon interaction


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