Size effect in thermoelectric power factor of nondegenerate and degenerate low-dimensional semiconductors
Journal
Materials Today: Proceedings
Journal Volume
4
Journal Issue
12
Start Page
12368
End Page
12373
ISSN
22147853
Date Issued
2017
Author(s)
Abstract
Low-dimensional materials have been known to give high thermoelectric (TE) performance by reducing the confinement length of the materials. Recently, we have shown that the TE power factor of low-dimensional semiconductors depends not only on the confinement length, but also on the thermal de Broglie wavelength of electrons or holes [Phys. Rev. Lett. 117, 036602 (2016)], in which the calculation was performed by assuming the semiconductors to be nondegenerate, i.e., we approximated the Fermi energy to lie only within the energy band gap, or in other words, the low doping approximation. Now, in this work, we generalize the previous results considering the degenerate case, in which the Fermi energy can exist in the valence or conduction bands, thus enabling a full consideration of heavy doping. An analytical formula for the TE power factor is derived to describe the size effect in the power factor of the low-dimensional semiconductors. We find that for both nondegenerate and degenerate cases, the TE power factor is enhanced in one- and two-dimensional semiconductors when the confinement length is smaller than the thermal de Broglie wavelength of the semiconductors, with Fermi energy around top (bottom) of valence (conduction) band for the p-type (n-type) semiconductors.
Subjects
Confinement Length Effect
Low-dimensional Semiconductors
Thermal De Broglie Wavelength
Thermoelectric Power Factor
Conduction Bands
Electric Power Factor
Energy Gap
Semiconductor Doping
Thermoelectric Power
Confinement Length Effect
De Broglie Wavelength
Degenerate Case
Length Effects
Low-dimensional Semiconductors
Nondegenerate
Sizes Effect
Thermal
Thermal De Broglie Wavelength
Thermoelectric Power Factors
Fermi Level
SDGs
Publisher
Elsevier Ltd
Type
conference paper