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Why So Colourful? On the Optical Properties of Silicon Nanocrystals

  • Author / Creator
    Regina Sinelnikov
  • Owing to their rich, tailorable surface chemistry, low toxicity, and elemental abundance,silicon nanocrystals (SiNCs) present an attractive alternative to fluorescentorganic dyes and traditional quantum dots for bioimaging, optoelectronics, and chemicalsensors. These applications capitalize on the optical properties of SiNCs, which arenot fully understood. Thus, the aim of this thesis was to gain a fundamental insightinto the optical response of SiNCs and the factors that affect it. Size, surface chemistry,oxidation, and attachment of conjugated surface groups were taken into considerationwhen evaluating factors influencing the photoluminescence (PL) of SiNCs.First, temperature-dependent steady-state and time-resolved PL measurements ofSiNCs of different sizes and surface functionalities were carried out. A general emissionmechanism based on the observed phenomena was proposed, suggesting that surfacegroups play a crucial role in SiNC PL. Next, the effect of oxidation on the stabilityof the SiNC optical response was evaluated. The convergence of the SiNC PL to thesame region of the visible spectrum, regardless of the initial SiNC PL, was postulated tooccur due to the formation of surface suboxide species. Lastly, the effect of interfacingSiNCs with conjugated surface groups was explored. Scanning tunneling spectroscopyrevealed the formation of in-gap states, which accounted for the observed red-shift inSiNC PL, thus illustrating another way to tune SiNC PL via surface chemistry.Overall, the research presented in this thesis demonstrated the intricate relationshipthat exists between size and surface when it comes to SiNC optical response, whichshould be taken into consideration for any future application design.

  • Subjects / Keywords
  • Graduation date
    Spring 2019
  • Type of Item
    Thesis
  • Degree
    Doctor of Philosophy
  • DOI
    https://doi.org/10.7939/r3-bxyh-vg39
  • License
    Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.