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Title: Dislocation related droop in InGaN/GaN light emitting diodes investigated via cathodoluminescence

Today's energy saving solutions for general illumination rely on efficient white light emitting diodes (LEDs). However, the output efficiency droop experienced in InGaN based LEDs with increasing current injection is a serious limitation factor for future development of bright white LEDs. We show using cathodoluminescence (CL) spatial mapping at different electron beam currents that threading dislocations are active as nonradiative recombination centers only at high injection conditions. At low current, the dislocations are inactive in carrier recombination due to local potentials, but these potentials are screened by carriers at higher injection levels. In CL images, this corresponds to the increase of the dark contrast around dislocations with the injection (excitation) density and can be linked with droop related to the threading dislocations. Our data indicate that reduction of droop in the future efficient white LED can be achieved via a drastic reduction of the dislocation density by using, for example, bulk native substrates.
Authors:
 [1] ;  [2] ;  [3] ;  [2] ;  [4] ;  [1] ;  [4] ;  [5]
  1. Department of Physics, Chemistry and Biology, Linköping University, SE-581 83 Linköping (Sweden)
  2. GLO AB, Scheelevägen 22, SE-22363 Lund (Sweden)
  3. Solid State Physics, Lund University, Box 118, SE-22100 Lund (Sweden)
  4. (Sweden)
  5. (Japan)
Publication Date:
OSTI Identifier:
22486260
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 107; Journal Issue: 25; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; CARRIERS; CATHODOLUMINESCENCE; CURRENTS; DISLOCATIONS; ELECTRON BEAMS; EXCITATION; GALLIUM NITRIDES; INDIUM CHLORIDES; LIGHT EMITTING DIODES; POTENTIALS; RECOMBINATION; SUBSTRATES