Thermoelectric efficiency in model nanowires
Author(s)
Advisor
Gülseren, OğuzDate
2013Publisher
Bilkent University
Language
English
Type
ThesisItem Usage Stats
198
views
views
65
downloads
downloads
Abstract
Nowadays, the use of thermoelectric semiconductor devices are limited by their
low efficiencies. Therefore, there is a huge amount of research effort to get high
thermoelectric efficient materials with a fair production value. To this end, one
important possibility for optimizing a material’s thermoelectric properties is reshaping
their geometry. The main purpose of this thesis is to present a detailed
analysis of thermoelectric efficiency of 2 lead systems with various geometries in
terms of linear response theory, as well as 3 lead nanowire system in terms of the
linear response and nonlinear response theories. The thermoelectric efficiency
both in the linear response and nonlinear response regime of a model nanowire
was calculated based on Landauer-B¨uttiker formalism. In this thesis, first of all,
the electron transmission probability of the system at the hand, i.e. 2 lead or 3
lead systems are investigated by using R-matrix theory. Next, we make use of
these electron transmission probability of model systems to find thermoelectric
transport coefficients in 2 lead and 3 lead nanowires. Consequently, the effect of
inelastic scattering is incorporated with a fictitious third lead in the 3 lead system.
The efficiency at maximum power is especially useful to define the optimum
working conditions of nanowire as a heat engine. Contrary to general expectation,
increasing the strength of inelastic scattering is shown to be a means of making
improved thermoelectric materials. A controlled coupling of the nanowire to a
phonon reservoir for instance could be a way to increase the efficiency of nanowires
for better heat engines.
Keywords
Thermoelectric effectsQuantum wires
Electron and Heat transport
Scattering theory
R-matrix theory
Transport properties
Nanoscale systems