University of Illinois Urbana-Champaign

Thermoelectric properties of polysilicon inverse opals

Ma, Jun

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Ma_Jun.pdf

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https://hdl.handle.net/2142/31007

Description

Title
Thermoelectric properties of polysilicon inverse opals
Author(s)
Ma, Jun
Issue Date
2012-05-22T00:21:13Z
Director of Research (if dissertation) or Advisor (if thesis)
Sinha, Sanjiv
Department of Study
Mechanical Sci & Engineering
Discipline
Mechanical Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
M.S.
Degree Level
Thesis
Date of Ingest
2012-05-22T00:21:13Z
Keyword(s)
  • Thermoelectrics
  • Inverse opal
Abstract
Nanostructured single-crystal silicon exhibits a remarkable increase in the gure of merit for thermoelectric energy conversion. Here we theoretically and experimentally(partial) investigate a similar enhancement for polycrystalline silicon structured as an inverse opal. An inverse opal provides nanoscale grains and a thin- lm like geometry to scatter phonons preferentially over electrons. Using solutions to the Boltzmann transport equation for electrons and phonons, we show that the gure of merit at 300 K is fteen times that of bulk single-crystal silicon. Our models predict that grain boundaries are more e ective than surfaces in enhancing the figure of merit. We provide insight into this e ect and show that preserving a grain size smaller than the shell thickness of the inverse opal increases the gure of merit by as much as 50% when the ratio between the two features is a third. At 600 K, the figure of merit is as high as 0.6 for a shell thickness of 10 nm. We also measured the thermal conductivity of such nanostructures, and a more accurate thermal transport model is provided based on the experimental results.
Graduation Semester
2012-05
Permalink
http://hdl.handle.net/2142/31007
Copyright and License Information
Copyright 2012 Jun Ma

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