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Title: Si quantum dots in silicon nitride: Quantum confinement and defects

Luminescence of amorphous Si quantum dots (Si QDs) in a hydrogenated silicon nitride (SiN{sub x}:H) matrix was examined over a broad range of stoichiometries from Si{sub 3}N{sub 2.08} to Si{sub 3}N{sub 4.14}, to optimize light emission. Plasma-enhanced chemical vapor deposition was used to deposit hydrogenated SiN{sub x} films with excess Si on Si (001) substrates, with stoichiometry controlled by variation of the gas flow rates of SiH{sub 4} and NH{sub 3} gases. The compositional and optical properties were analyzed by Rutherford backscattering spectroscopy, elastic recoil detection, spectroscopic ellipsometry, photoluminescence (PL), time-resolved PL, and energy-filtered transmission electron microscopy. Ultraviolet-laser-excited PL spectra show multiple emission bands from 400 nm (3.1 eV) to 850 nm (1.45 eV) for different Si{sub 3}N{sub x} compositions. There is a red-shift of the measured peaks from ∼2.3 eV to ∼1.45 eV as Si content increases, which provides evidence for quantum confinement. Higher N content samples show additional peaks in their PL spectra at higher energies, which we attribute to defects. We observed three different ranges of composition where Tauc band gaps, PL, and PL lifetimes change systematically. There is an interesting interplay of defect luminescence and, possibly, small Si QD luminescence observed in the intermediate range of compositions (∼Si{sub 3}N{sub 3.15}) in whichmore » the maximum of light emission is observed.« less
Authors:
; ; ; ; ;  [1] ;  [2]
  1. Department of Physics and Astronomy, The University of Western Ontario, London, Ontario N6A 3K7 (Canada)
  2. Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E1 (Canada)
Publication Date:
OSTI Identifier:
22493025
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 118; Journal Issue: 22; 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; 77 NANOSCIENCE AND NANOTECHNOLOGY; AMMONIA; CHEMICAL VAPOR DEPOSITION; DEFECTS; ELLIPSOMETRY; GAS FLOW; HYDROGENATION; OPTICAL PROPERTIES; PHOTOLUMINESCENCE; PLASMA; QUANTUM DOTS; RECOILS; RUTHERFORD BACKSCATTERING SPECTROSCOPY; SILANES; SILICON; SILICON NITRIDES; SPECTRA; STOICHIOMETRY; TIME RESOLUTION; TRANSMISSION ELECTRON MICROSCOPY; ULTRAVIOLET RADIATION