Size-dependent efficiency and efficiency droop of blue InGaN micro-light emitting diodes

Pengfei Tian, Jonathan McKendry, Zheng Gong, Benoit Jack Eloi Guilhabert, Ian Watson, Erdan Gu, Zhizhong Chen, Guoyi Zhang, Martin Dawson

Research output: Contribution to journalArticlepeer-review

186 Citations (Scopus)


The mechanisms of size-dependent efficiency and efficiency droop of blue InGaN micro-pixel light emitting diodes (LEDs) have been investigated experimentally and by simulation. Electrical characterisation confirms the improvement of current spreading for smaller LEDs, which enables the achievement of the higher efficiency at high injection current densities. Owing to the higher ratio of sidewall perimeter to mesa area of smaller LEDs, a lower efficiency was observed at a low injection current density, resulting from defect-related Shockley-Read-Hall non-radiative recombination. We demonstrate that such sidewall etch defects can be partially recovered by increased thermal annealing time, consequently improving the efficiency at low current densities
Original languageEnglish
Article number231110
Number of pages4
JournalApplied Physics Letters
Issue number23
Publication statusPublished - 6 Dec 2012


  • efficiency droop
  • light-emitting diode (LED)
  • current density
  • gallium compounds


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