Low thermal conductivity in condensed matter is critical to a diverse range of technologies, such as high efficient thermoelectrics and thermal insulation. It is thus important to fabricate, grow, or assemble structures that can reach a low limit. For III-nitride with high intrinsic thermal conductivity, how to utilize periodic nanostructures to manipulate phonons and achieve controllable low thermal conductivity is rarely studied. Recently, periodically self-organized arrays of nano-grooves on AlN (0001) surface have been observed experimentally. Inspired by this, we perform non-equilibrium molecular dynamics simulations to explore the thermal transport in such structures. The dependence of thermal conductivity on the periodic length of the nano-grooves and the angle of the side wall is systematically studied. Remarkably, results show that the thermal conductivity has a minimum value for a critical periodic length, which is one order of magnitude lower than the counterpart bulk value. The intrinsic high thermal conductivity of AlN can be robustly manipulated to the desired value by rationally designing the periodic nano-groove structure on the surface of the film. The detailed mechanism is provided by the frequency dependent heat current spectrum and phonon polarization analysis, along with the semi-empirical theoretical model. The understanding gained from this study offers an alternative route for tailoring the thermal conductivity of nanofilms by periodically patterned nano-grooves, which has large impact in relevant applications involving thermal transport.
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26 September 2016
Research Article|
September 28 2016
Tailoring thermal conductivity of AlN films by periodically aligned surface nano-grooves
Xiaoliang Zhang;
Xiaoliang Zhang
a)
1Institute of Mineral Engineering, Division of Materials Science and Engineering, Faculty of Georesources and Materials Engineering,
RWTH Aachen University
, 52064 Aachen, Germany
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Xiaojing Gong;
Xiaojing Gong
a)
2Suzhou Institute of Nano-tech and Nano-bionics,
Chinese Academy of Sciences
, 215123 Suzhou, China
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Yanguang Zhou;
Yanguang Zhou
3Aachen Institute for Advanced Study in Computational Engineering Science (AICES),
RWTH Aachen University
, 52062 Aachen, Germany
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Ming Hu
Ming Hu
b)
1Institute of Mineral Engineering, Division of Materials Science and Engineering, Faculty of Georesources and Materials Engineering,
RWTH Aachen University
, 52064 Aachen, Germany
3Aachen Institute for Advanced Study in Computational Engineering Science (AICES),
RWTH Aachen University
, 52062 Aachen, Germany
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a)
X. Zhang and X. Gong contributed equally to this work.
b)
Author to whom correspondence should be addressed. Electronic mail: hum@ghi.rwth-aachen.de.
Appl. Phys. Lett. 109, 133107 (2016)
Article history
Received:
May 19 2016
Accepted:
September 19 2016
Citation
Xiaoliang Zhang, Xiaojing Gong, Yanguang Zhou, Ming Hu; Tailoring thermal conductivity of AlN films by periodically aligned surface nano-grooves. Appl. Phys. Lett. 26 September 2016; 109 (13): 133107. https://doi.org/10.1063/1.4963822
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