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Title: Tunable thermoelectric transport in nanomeshes via elastic strain engineering

Abstract

Recent experimental explorations of silicon nanomeshes have shown that the unique metastructures exhibit reduced thermal conductivity while preserving bulk electrical conductivity via feature sizes between relevant phonon and electron mean free paths, aiding in the continued promise that nanometer-scale engineering may further enhance thermoelectric behavior. Here, we introduce a strategy for tuning thermoelectric transport phenomena in semiconductor nanomeshes via heterogeneous elastic strain engineering, using silicon as a model material for demonstration of the concept. By combining analytical models for electron mobility in uniformly stressed silicon with finite element analysis of strained silicon nanomeshes in a lumped physical model, we show that the nonuniform and multiaxial strain fields defined by the nanomesh geometry give rise to spatially varying band shifts and warping, which in aggregate accelerate electron transport along directions of applied stress. This allows for global electrical conductivity and Seebeck enhancements beyond those of homogenous samples under equivalent far-field stresses, ultimately increasing thermoelectric power factor nearly 50% over unstrained samples. The proposed concept and structures—generic to a wide class of materials with large dynamic ranges of elastic strain in nanoscale volumes—may enable a new pathway for active and tunable control of transport properties relevant to waste heat scavenging and thermalmore » management.« less

Authors:
Publication Date:
OSTI Identifier:
22395764
Resource Type:
Journal Article
Journal Name:
Applied Physics Letters
Additional Journal Information:
Journal Volume: 106; Journal Issue: 11; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0003-6951
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ELECTRIC CONDUCTIVITY; ELECTRON MOBILITY; ELECTRONS; FINITE ELEMENT METHOD; MEAN FREE PATH; NANOSTRUCTURES; PHONONS; SEEBECK EFFECT; SEMICONDUCTOR MATERIALS; SILICON; STRAINS; STRESSES; THERMAL CONDUCTIVITY; THERMOELECTRICITY

Citation Formats

Piccione, Brian, and Gianola, Daniel S., E-mail: gianola@seas.upenn.edu. Tunable thermoelectric transport in nanomeshes via elastic strain engineering. United States: N. p., 2015. Web. doi:10.1063/1.4915270.
Piccione, Brian, & Gianola, Daniel S., E-mail: gianola@seas.upenn.edu. Tunable thermoelectric transport in nanomeshes via elastic strain engineering. United States. https://doi.org/10.1063/1.4915270
Piccione, Brian, and Gianola, Daniel S., E-mail: gianola@seas.upenn.edu. 2015. "Tunable thermoelectric transport in nanomeshes via elastic strain engineering". United States. https://doi.org/10.1063/1.4915270.
@article{osti_22395764,
title = {Tunable thermoelectric transport in nanomeshes via elastic strain engineering},
author = {Piccione, Brian and Gianola, Daniel S., E-mail: gianola@seas.upenn.edu},
abstractNote = {Recent experimental explorations of silicon nanomeshes have shown that the unique metastructures exhibit reduced thermal conductivity while preserving bulk electrical conductivity via feature sizes between relevant phonon and electron mean free paths, aiding in the continued promise that nanometer-scale engineering may further enhance thermoelectric behavior. Here, we introduce a strategy for tuning thermoelectric transport phenomena in semiconductor nanomeshes via heterogeneous elastic strain engineering, using silicon as a model material for demonstration of the concept. By combining analytical models for electron mobility in uniformly stressed silicon with finite element analysis of strained silicon nanomeshes in a lumped physical model, we show that the nonuniform and multiaxial strain fields defined by the nanomesh geometry give rise to spatially varying band shifts and warping, which in aggregate accelerate electron transport along directions of applied stress. This allows for global electrical conductivity and Seebeck enhancements beyond those of homogenous samples under equivalent far-field stresses, ultimately increasing thermoelectric power factor nearly 50% over unstrained samples. The proposed concept and structures—generic to a wide class of materials with large dynamic ranges of elastic strain in nanoscale volumes—may enable a new pathway for active and tunable control of transport properties relevant to waste heat scavenging and thermal management.},
doi = {10.1063/1.4915270},
url = {https://www.osti.gov/biblio/22395764}, journal = {Applied Physics Letters},
issn = {0003-6951},
number = 11,
volume = 106,
place = {United States},
year = {Mon Mar 16 00:00:00 EDT 2015},
month = {Mon Mar 16 00:00:00 EDT 2015}
}