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Title: Investigating the origin of efficiency droop by profiling the temperature across the multi-quantum well of an operating light-emitting diode

Performance degradation resulting from efficiency droop during high-power operation is a critical problem in the development of high-efficiency light-emitting diodes (LEDs). In order to resolve the efficiency droop and increase the external quantum efficiency of LEDs, the droop's origin should be identified first. To experimentally investigate the cause of efficiency droop, we used null-point scanning thermal microscopy to quantitatively profile the temperature distribution on the cross section of the epi-layers of an operating GaN-based vertical LED with nanoscale spatial resolution at four different current densities. The movement of temperature peak towards the p-GaN side as the current density increases suggests that more heat is generated by leakage current than by Auger recombination. We therefore suspect that at higher current densities, current leakage becomes the dominant cause of the droop problem.
Authors:
; ;  [1] ;  [1] ;  [2] ;  [3] ;  [2] ;  [4] ;  [3] ;  [2]
  1. Department of Mechanical Engineering, Korea University, Seoul 136-701 (Korea, Republic of)
  2. (Korea, Republic of)
  3. Department of Nanophotonics, Korea University, Seoul 136-713 (Korea, Republic of)
  4. LG Innotek Ltd., Paju City, Gyeonggi Province 413-901 (Korea, Republic of)
Publication Date:
OSTI Identifier:
22415175
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 106; Journal Issue: 4; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; CURRENT DENSITY; GALLIUM NITRIDES; LAYERS; LEAKAGE CURRENT; LIGHT EMITTING DIODES; MICROSCOPY; PERFORMANCE; QUANTUM EFFICIENCY; QUANTUM WELLS; RECOMBINATION; SPATIAL RESOLUTION; TEMPERATURE DISTRIBUTION