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Title: Homogeneous and inhomogeneous sources of optical transition broadening in room temperature CdSe/ZnS nanocrystal quantum dots

We perform photoluminescence excitation measurements on individual CdSe/ZnS nanocrystal quantum dots (NCQDs) at room temperature to study optical transition energies and broadening. The observed features in the spectra are identified and compared to calculated transition energies using an effective mass model. The observed broadening is attributed to phonon broadening, spectral diffusion, and size and shape inhomogeneity. The former two contribute to the broadening transitions in individual QDs, while the latter contributes to the QD-to-QD variation. We find that phonon broadening is often not the dominant contribution to transition line widths, even at room temperature, and that broadening does not necessarily increase with transition energy. This may be explained by differing magnitude of spectral diffusion for different quantum-confined states.
Authors:
;  [1]
  1. Department of Physics, Case Western Reserve University, Cleveland, Ohio 44106 (United States)
Publication Date:
OSTI Identifier:
22350862
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 105; Journal Issue: 14; 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; CADMIUM SELENIDES; DIFFUSION; EFFECTIVE MASS; EXCITATION; NANOMATERIALS; PHONONS; PHOTOLUMINESCENCE; QUANTUM DOTS; SPECTRA; TEMPERATURE RANGE 0273-0400 K; ZINC SULFIDES