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Influence of surface states and size effects on the Seebeck coefficient and electrical resistance of Bi1−xSbxnanowire arrays

Cassinelli, M. and Müller, S. and Voss, K.-O. and Trautmann, C. and Völklein, F. and Gooth, J. and Nielsch, K. and Toimil-Molares, M. E. (2017):
Influence of surface states and size effects on the Seebeck coefficient and electrical resistance of Bi1−xSbxnanowire arrays.
9, In: Nanoscale, (9), Royal Society of Chemistry, pp. 3169-3179, ISSN 2040-3364, DOI: 10.1039/C6NR09624G,
[Online-Edition: https://doi.org/10.1039/C6NR09624G],
[Article]

Abstract

The Seebeck coefficient and electrical resistance of Bi1−xSbx nanowire arrays electrodeposited in etched ion-track membranes have been investigated as a function of wire diameter (40–750 nm) and composition (0 ≤ x ≤ 1). The experimental data reveal a non-monotonic dependence between thermopower and wire diameter for three different compositions. Thus, the thermopower values decrease with decreasing wire diameter, exhibiting a minimum around ∼60 nm. This non-monotonic dependence of the Seebeck coefficient is attributed to the interplay of surface and bulk states. On the one hand, the metallic properties of the surface states can contribute to decreasing the thermopower of the nanostructure with increasing surface-to-volume ratio. On the other hand, for wires thinner than ∼60 nm, the relative increase of the thermopower can be tentatively attributed to the presence of quantum-size effects on both surface and bulk states. These measurements contribute to a better understanding of the interplay between bulk and surface states in nanostructures, and indicate that the decrease of Seebeck coefficient with decreasing diameter caused by the presence of surfaces states can possibly be overcome for even thinner nanowires.

Item Type: Article
Erschienen: 2017
Creators: Cassinelli, M. and Müller, S. and Voss, K.-O. and Trautmann, C. and Völklein, F. and Gooth, J. and Nielsch, K. and Toimil-Molares, M. E.
Title: Influence of surface states and size effects on the Seebeck coefficient and electrical resistance of Bi1−xSbxnanowire arrays
Language: English
Abstract:

The Seebeck coefficient and electrical resistance of Bi1−xSbx nanowire arrays electrodeposited in etched ion-track membranes have been investigated as a function of wire diameter (40–750 nm) and composition (0 ≤ x ≤ 1). The experimental data reveal a non-monotonic dependence between thermopower and wire diameter for three different compositions. Thus, the thermopower values decrease with decreasing wire diameter, exhibiting a minimum around ∼60 nm. This non-monotonic dependence of the Seebeck coefficient is attributed to the interplay of surface and bulk states. On the one hand, the metallic properties of the surface states can contribute to decreasing the thermopower of the nanostructure with increasing surface-to-volume ratio. On the other hand, for wires thinner than ∼60 nm, the relative increase of the thermopower can be tentatively attributed to the presence of quantum-size effects on both surface and bulk states. These measurements contribute to a better understanding of the interplay between bulk and surface states in nanostructures, and indicate that the decrease of Seebeck coefficient with decreasing diameter caused by the presence of surfaces states can possibly be overcome for even thinner nanowires.

Journal or Publication Title: Nanoscale
Volume: 9
Number: 9
Publisher: Royal Society of Chemistry
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Ion-Beam-Modified Materials
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences
Date Deposited: 29 Dec 2017 10:32
DOI: 10.1039/C6NR09624G
Official URL: https://doi.org/10.1039/C6NR09624G
Funders: The Deutsche Forschungsgemeinschaft (DFG) is acknowledged for supporting this research within the priority programs SPP 1386 and SPP 1666.
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