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Efficiency Enhancement Mechanism of an Underlying Layer in GaInN‐Based Green Light–Emitting Diodes
Author(s) -
Han Dong-Pyo,
Ishimoto Seiji,
Mano Ryoya,
Lu Weifang,
Iwaya Motoaki,
Takeuchi Tetsuya,
Kamiyama Satoshi,
Akasaki Isamu
Publication year - 2020
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.201900713
Subject(s) - light emitting diode , optoelectronics , materials science , quantum efficiency , voltage droop , electroluminescence , diode , layer (electronics) , voltage , nanotechnology , physics , quantum mechanics , voltage divider
To investigate the mechanism of efficiency enhancement achieved by introducing underlying layers (ULs) in green light–emitting diodes (LEDs), this study compares green GaInN‐based LEDs with an identical epitaxial structure and chip structure comprising different types of ULs, i.e., without an UL or with a GaInN or AlInN UL. To this end, the samples are analyzed with respect to several characteristics, such as their electroluminescence spectra, internal quantum efficiency, recombination coefficients, joint density of states, localized state, and Stokes shift. Based on these analyses and considerations, a mechanism of efficiency enhancement achieved by introducing ULs is proposed, and the degradation mechanisms responsible for the green gap, efficiency droop, and electrical potential drop in green LEDs are also discussed. The results show that the piezoelectric field in the In‐clustering region and the nonradiative recombination center simultaneously play crucial roles in the degradation mechanisms for green LEDs.