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Title:Thermoelectric properties of polysilicon inverse opals
Author(s):Ma, Jun
Advisor(s):Sinha, Sanjiv
Department / Program:Mechanical Sci & Engineering
Discipline:Mechanical Engineering
Degree Granting Institution:University of Illinois at Urbana-Champaign
Degree:M.S.
Genre:Thesis
Subject(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.
Issue Date:2012-05-22
URI:http://hdl.handle.net/2142/31007
Rights Information:Copyright 2012 Jun Ma
Date Available in IDEALS:2012-05-22
Date Deposited:2012-05


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