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Title: The influence of non-idealities on the thermoelectric power factor of nanostructured superlattices

Cross-plane superlattices composed of nanoscale layers of alternating potential wells and barriers have attracted great attention for their potential to provide thermoelectric power factor improvements and higher ZT figure of merit. Previous theoretical works have shown that the presence of optimized potential barriers could provide improvements to the Seebeck coefficient through carrier energy filtering, which improves the power factor by up to 40%. However, experimental corroboration of this prediction has been extremely scant. In this work, we employ quantum mechanical electronic transport simulations to outline the detrimental effects of random variation, imperfections, and non-optimal barrier shapes in a superlattice geometry on these predicted power factor improvements. Thus, we aim to assess either the robustness or the fragility of these theoretical gains in the face of the types of variation one would find in real material systems. We show that these power factor improvements are relatively robust against: overly thick barriers, diffusion of barriers into the body of the wells, and random fluctuations in barrier spacing and width. However, notably, we discover that extremely thin barriers and random fluctuation in barrier heights by as little as 10% is sufficient to entirely destroy any power factor benefits of the optimized geometry. Ourmore » results could provide performance optimization routes for nanostructured thermoelectrics and elucidate the reasons why significant power factor improvements are not commonly realized in superlattices, despite theoretical predictions.« less
Authors:
; ;  [1] ;  [2]
  1. Institute for Microelectronics, Technical University of Vienna, Gußhausstraße 27-29/E360, A-1040 Wien (Austria)
  2. School of Engineering, University of Warwick, Coventry CV4 7AL (United Kingdom)
Publication Date:
OSTI Identifier:
22493024
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 118; Journal Issue: 22; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 77 NANOSCIENCE AND NANOTECHNOLOGY; ELECTRON TRANSFER; FLUCTUATIONS; NANOSTRUCTURES; OPTIMIZATION; PERFORMANCE; POTENTIALS; POWER FACTOR; QUANTUM MECHANICS; SEEBECK EFFECT; SIMULATION; SUPERLATTICES