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Title: Origin of radiative recombination and manifestations of localization effects in GaAs/GaNAs core/shell nanowires

Radiative carrier recombination processes in GaAs/GaNAs core/shell nanowires grown by molecular beam epitaxy on a Si substrate are systematically investigated by employing micro-photoluminescence (μ-PL) and μ-PL excitation (μ-PLE) measurements complemented by time-resolved PL spectroscopy. At low temperatures, alloy disorder is found to cause localization of photo-excited carriers leading to predominance of optical transitions from localized excitons (LE). Some of the local fluctuations in N composition are suggested to lead to strongly localized three-dimensional confining potential equivalent to that for quantum dots, based on the observation of sharp and discrete PL lines within the LE contour. The localization effects are found to have minor influence on PL spectra at room temperature due to thermal activation of the localized excitons to extended states. Under these conditions, photo-excited carrier lifetime is found to be governed by non-radiative recombination via surface states which is somewhat suppressed upon N incorporation.
Authors:
; ; ;  [1] ;  [2]
  1. Department of Physics, Chemistry and Biology, Linköping University, 58183 Linköping (Sweden)
  2. Graduate School of Science and Engineering, Ehime University, 790-8577 Matsuyama (Japan)
Publication Date:
OSTI Identifier:
22395589
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 105; Journal Issue: 25; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
77 NANOSCIENCE AND NANOTECHNOLOGY; CARRIER LIFETIME; CHARGE CARRIERS; EMISSION SPECTROSCOPY; EXCITATION; EXCITONS; FLUCTUATIONS; GALLIUM ARSENIDES; MOLECULAR BEAM EPITAXY; NANOWIRES; PHOTOLUMINESCENCE; QUANTUM DOTS; RECOMBINATION; SILICON; SUBSTRATES; SURFACES; THREE-DIMENSIONAL LATTICES; TIME RESOLUTION