Photoluminescence and Patterning of Silicon Nanocrystals

• Author / Creator

  Rodriguez Nunez, Jose R.

• Silicon nanocrystals (Si-NCs) have been suggested for sensing and lasing applications due to their low-toxicity and compatibility with existing microelectronic technologies. Their broad luminescence, due to homogeneous (150 meV or 40 nm at room temperature) and inhomogeneous broadening, may hamper their incorporation into the aforementioned applications. This thesis begins with a discussion on the optical properties of Si-NCs (Chapter one). Then, it presents methods to decrease the breadth of the luminescence obtained upon photoexcitation of Si-NCs prepared via thermal processing of hydrogen silsesquioxane (HSQ). Narrowing of luminescence profile can be accomplished by sensitization of sharply emissive species. Chapter two outlines a solution processable method to obtain sharp, Si-NC sensitized, erbium luminescence. The luminescence obtained (FWHM Er emission ~ 40 nm) lies in the low-loss window of silica fiber optics and may be useful for telecommunication applications. A method to pattern oxide-embedded Si-NCs using amine containing block copolymers is presented in Chapter 3. This method utilizes gelation of HSQ with amine moieties in the polymer. This straightforward, inexpensive, non-lithographic, patterning technique was also extended to germanium features. Chapter four presents a photo-assisted etching method of Si-NCs. This unique etching method provides a means to control the optical properties of Si-NCs by exposing a Si-NC:HF:HCl mixture to light of varying wavelengths. The narrowest luminescence obtained using this technique is approximately 80 nm (twice the width of homogeneously broadened NCs). A method to prepare Si-NC coated microcavities is presented in Chapter five. The coupling of NC luminescence to optical cavities produces high quality, whispering-gallery modes which results in sharp peaks (FWHM < 0.5 nm) over the broad PL spectrum. A proof-of-concept refractometric sensor using these cavities is also discussed. Finally, Chapter 6 includes general conclusions on the work presented and outlines new research that can be performed to enable incorporation of these materials into everyday technologies.

• Subjects / Keywords

  • Erbium
  • Block copolymer patterning
  • Patterning
  • Size distribution
  • Photoluminescence
  • Sensing
  • Silicon Nanocrystals

• Graduation date

  Spring 2012

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R39W0992B

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.