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Title: Step-like increase of quantum yield of 1.5 μm Er-related emission in SiO{sub 2} doped with Si nanocrystals

We investigate the excitation dependence of the efficiency of the Si nanocrystals-mediated photoluminescence from Er{sup 3+} ions embedded in a SiO{sub 2} matrix. We show that the quantum yield of this emission increases in a step-like manner with excitation energy. The subsequent thresholds of this characteristic dependence are approximately given by the sum of the Si nanocrystals bandgap energy and multiples of 0.8 eV, corresponding to the energy of the first excited state of Er{sup 3+} ions. By comparing differently prepared materials, we explicitly demonstrate that the actual values of the threshold energies and the rate of the observed increase of the external quantum yield depend on sample characteristics—the size, the optical activity and the concentration of Si nanocrystals as well Er{sup 3+} ions to Si nanocrystals concentration ratio. In that way, detailed insights into the efficient excitation of Er{sup 3+} ions are obtained. In particular, the essential role of the hot-carrier-mediated Er excitation route is established, with a possible application perspective for highly efficient future-generation photovoltaics.
Authors:
; ;  [1]
  1. Van der Waals-Zeeman Institute, University of Amsterdam, Science Park 904, NL-1098 XH Amsterdam (Netherlands)
Publication Date:
OSTI Identifier:
22413096
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 117; Journal Issue: 6; 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; APPROXIMATIONS; CHARGE CARRIERS; COMPARATIVE EVALUATIONS; CONCENTRATION RATIO; DOPED MATERIALS; ERBIUM IONS; EV RANGE; EXCITATION; EXCITED STATES; MATRIX MATERIALS; NANOSTRUCTURES; OPTICAL ACTIVITY; PHOTOLUMINESCENCE; PHOTOVOLTAIC EFFECT; SILICON; SILICON OXIDES; THRESHOLD ENERGY