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Title: Absence of quantum confinement effects in the photoluminescence of Si{sub 3}N{sub 4}–embedded Si nanocrystals

Superlattices of Si-rich silicon nitride and Si{sub 3}N{sub 4} are prepared by plasma-enhanced chemical vapor deposition and, subsequently, annealed at 1150 °C to form size-controlled Si nanocrystals (Si NCs) embedded in amorphous Si{sub 3}N{sub 4}. Despite well defined structural properties, photoluminescence spectroscopy (PL) reveals inconsistencies with the typically applied model of quantum confined excitons in nitride-embedded Si NCs. Time-resolved PL measurements demonstrate 10{sup 5} times faster time-constants than typical for the indirect band structure of Si NCs. Furthermore, a pure Si{sub 3}N{sub 4} reference sample exhibits a similar PL peak as the Si NC samples. The origin of this luminescence is discussed in detail on the basis of radiative defects and Si{sub 3}N{sub 4} band tail states in combination with optical absorption measurements. The apparent absence of PL from the Si NCs is explained conclusively using electron spin resonance data from the Si/Si{sub 3}N{sub 4} interface defect literature. In addition, the role of Si{sub 3}N{sub 4} valence band tail states as potential hole traps is discussed. Most strikingly, the PL peak blueshift with decreasing NC size, which is often observed in literature and typically attributed to quantum confinement (QC), is identified as optical artifact by transfer matrix method simulations of themore » PL spectra. Finally, criteria for a critical examination of a potential QC-related origin of the PL from Si{sub 3}N{sub 4}-embedded Si NCs are suggested.« less
Authors:
; ; ;  [1] ;  [2] ;  [3] ; ; ; ;  [4] ;  [4] ;  [5] ; ; ; ;  [6] ; ; ;  [7]
  1. Faculty of Engineering, IMTEK, Albert-Ludwigs-University Freiburg, Georges-Köhler-Allee 103, 79110 Freiburg (Germany)
  2. Department of Electronic and Electrical Engineering, Trinity College Dublin, Dublin 2 (Ireland)
  3. (KTH), Electrum 229, Kista SE-16440 (Sweden)
  4. MIND-IN2UB, Departament d'Electrònica, Universitat de Barcelona, C. Martí i Franquès, 1, 08028 Barcelona (Spain)
  5. (Spain)
  6. Faculty of Mathematics and Physics, Department of Chemical Physics and Optics, Charles University in Prague, Ke Karlovu 3, CZ-12116 Prague 2 (Czech Republic)
  7. Fraunhofer-Institut für Solare Energiesysteme ISE, Heidenhofstr. 2, 79110 Freiburg (Germany)
Publication Date:
OSTI Identifier:
22304388
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 115; Journal Issue: 20; 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; ABSORPTION; CHEMICAL VAPOR DEPOSITION; CRYSTALS; DEFECTS; ELECTRON SPIN RESONANCE; EXCITONS; INTERFACES; NANOMATERIALS; NANOSTRUCTURES; PHOTOLUMINESCENCE; PLASMA; SILICON; SILICON NITRIDES; SIMULATION; SPECTRA; SUPERLATTICES; TIME RESOLUTION; TRANSFER MATRIX METHOD; TRAPS