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Anisotropic temperature-dependent thermal conductivity by an Al2O3 interlayer in Al2O3/ZnO superiattice films

Title
Anisotropic temperature-dependent thermal conductivity by an Al2O3 interlayer in Al2O3/ZnO superiattice films
Author
박진성
Keywords
thermal conductivity; superlattice films; phonon scattering; 3-omega measurement
Issue Date
2017-02
Publisher
IOP PUBLISHING LTD
Citation
NANOTECHNOLOGY, v. 28, no. 10, Article no. 105401
Abstract
The thermal conductivity of superlattice films is generally anisotropic and should be studied separately in the in-plane and cross-plane directions of the films. However, previous works have mostly focused on the cross-plane thermal conductivity because the electrons and phonons in the cross-plane direction of superlattice films may result in much stronger interface scattering than that in the in-plane direction. Nevertheless, it is highly desirable to perform systematic studies on the effect of interface formation in semiconducting superlattice films on both in-plane and cross-plane thermal conductivities. In this study, we determine both the in-plane and cross-plane thermal conductivities of Al2O3 (AO)/ZnO superlattice films grown by atomic layer deposition (ALD) on SiO2/Si substrates in the temperature range of 50-300 K by the four-point-probe 3-omega method. Our experimental results indicate that the formation of an atomic AO layer (0.82 nm) significantly contributes to the decrease of the cross-plane thermal conductivity of the AO/ZnO superlattice films compared with that of AO/ZnO thin films. The cross-plane thermal conductivity (0.26-0.63W m(-1) K-1 of the AO/ZnO superlattice films (with an AO layer of similar to 0.82 nm thickness) is approximately similar to 150%-370% less than the in-plane thermal conductivity (0.96-1.19W m-1 K-1) of the corresponding film, implying significant anisotropy. This indicates that the suppression of the cross-plane thermal conductivity is mainly attributed to the superlattice, rather than the nanograin columnar structure in the films. In addition, we theoretically analyzed strong anisotropic behavior of the in-plane and cross-plane thermal conductivities of the AO/ZnO superlattice films in terms of temperature dependence.
URI
https://iopscience.iop.org/article/10.1088/1361-6528/aa5985http://repository.hanyang.ac.kr/handle/20.500.11754/112930
ISSN
0957-4484; 1361-6528
DOI
10.1088/1361-6528/aa5985
Appears in Collections:
COLLEGE OF ENGINEERING[S](공과대학) > MATERIALS SCIENCE AND ENGINEERING(신소재공학부) > Articles
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