Cross-plane thermoelectric Seebeck coefficients in nanoscale Al 2 O 3 /ZnO superlattice films

Yo Seop Yoon, Won Yong Lee, No Won Park, Gil Sung Kim, Rafael Ramos, Kikkawa Takashi, Eiji Saitoh, Sang Mo Koo, Jin Seong Park, Sang Kwon Lee

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)

Abstract

Superlattice thin films, which are used in thermoelectric (TE) devices for small-scale solid-state cooling and for generating electrical power, have recently been attracting attention due to their low dimensionality, low thermal conductivity, and enhanced power factor. Considering the measurement techniques for characterizing TE properties, very limited information, including cross-plane Seebeck coefficients of superlattice films, has been reported. This information is required for the assessment of the interface between the films and to understand phonon scattering in superlattice films. In this report, thermally stable cross-plane thermoelectric Seebeck coefficients of Al 2 O 3 /ZnO (AO/ZnO) superlattice films are presented, at temperature differences (ΔT) ranging from 2 to 12 K. Longitudinal (in-plane) thermal diffusion in the Cu/AO/ZnO/Cu samples, which occurred during the measurements due to the size differences among the samples located between a micro-Peltier and aluminum nitride cooling plate, was investigated. The cross-plane Seebeck coefficients of 3- and 6-cycled AO/ZnO superlattice films were determined to be ∼9.4 ± 0.4 and ∼30.6 ± 0.7 μV K −1 , respectively, showing stable values in the evaluated ΔT range. Two distinct phenomena, in-plane thermal diffusion and the effect of the environment, were identified in cross-plane Seebeck measurements as dominant factors controlling the temperature coefficient of AO/ZnO superlattice films. In addition, a new TE parameter, the Seebeck temperature coefficient, was proposed for superlattice films.

Original languageEnglish
Pages (from-to)1670-1680
Number of pages11
JournalJournal of Materials Chemistry C
Volume7
Issue number6
DOIs
Publication statusPublished - 2019

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Chemistry

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