Si quantum dots in silicon nitride: Quantum confinement and defects

Journal Article · Mon Dec 14 00:00:00 EST 2015 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4936369· OSTI ID:22493025

Karner, V. L.; D'Ortenzio, R.; Chaudhary, S.; Mokry, C. R.; Simpson, P. J. ^[1]; Nguyen, P. H. ^[2]

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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)

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 which the maximum of light emission is observed.

• OSTI ID: 22493025
• Journal Information: Journal of Applied Physics, Vol. 118, Issue 22; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

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