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Title: Interplay of point defects, extended defects, and carrier localization in the efficiency droop of InGaN quantum wells light-emitting diodes investigated using spatially resolved electroluminescence and photoluminescence

We perform both spatially resolved electroluminescence (SREL) as a function of injection current and spatially resolved photoluminescence (SRPL) as a function of excitation power on InGaN quantum well blue light-emitting diodes to investigate the underlying physics for the phenomenon of the external quantum efficiency (EQE) droop. SREL allows us to study two most commonly observed but distinctly different droop behaviors on a single device, minimizing the ambiguity trying to compare independently fabricated devices. Two representative devices are studied: one with macroscopic scale material non-uniformity, the other being macroscopically uniform, but both with microscopic scale fluctuations. We suggest that the EQE–current curve reflects the interplay of three effects: nonradiative recombination through point defects, carrier localization due to either In composition or well width fluctuation, and nonradiative recombination of the extended defects, which is common to various optoelectronic devices. By comparing SREL and SRPL, two very different excitation/detection modes, we show that individual singular sites exhibiting either particularly strong or weak emission in SRPL do not usually play any significant and direct role in the EQE droop. We introduce a two-level model that can capture the basic physical processes that dictate the EQE–current dependence and describe the whole operating range of themore » device from 0.01 to 100 A/cm{sup 2}.« less
Authors:
 [1] ;  [2] ;  [2] ; ;  [1] ; ;  [3] ; ;  [4]
  1. Electrical and Computer Engineering Department and Energy Production and Infrastructure Center, University of North Carolina at Charlotte, Charlotte, North Carolina 28223 (United States)
  2. (China)
  3. R and D Center for Semiconductor Lighting, Chinese Academy of Sciences, Beijing 100083 (China)
  4. Department of Electronic Science and Fujian Engineering Research Center for Solid-State Lighting, Xiamen University, Xiamen, Fujian 361005 (China)
Publication Date:
OSTI Identifier:
22271251
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 115; Journal Issue: 2; Other Information: (c) 2014 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; 77 NANOSCIENCE AND NANOTECHNOLOGY; CAPTURE; CHARGE CARRIERS; COMPARATIVE EVALUATIONS; ELECTRIC CURRENTS; ELECTROLUMINESCENCE; EXCITATION; FLUCTUATIONS; GALLIUM NITRIDES; INDIUM COMPOUNDS; LIGHT EMITTING DIODES; PHOTOLUMINESCENCE; POINT DEFECTS; QUANTUM EFFICIENCY; QUANTUM WELLS; RECOMBINATION