TY - JOUR
T1 - Using Mosaicity to Tune Thermal Transport in Polycrystalline AlN Thin Films
AU - Singh, Shivkant
AU - Shervin, Shahab
AU - Sun, Haiding
AU - Yarali, Milad
AU - Chen, Jie
AU - Lin, Ronghui
AU - Li, Kuang-Hui
AU - Li, Xiaohang
AU - Ryou, Jae-Hyun
AU - Mavrokefalos, Anastassios
N1 - KAUST Repository Item: Exported on 2020-10-01
Acknowledgements: A. M. acknowledges financial support from the University of Houston. J.H.R. acknowledges partial support from the Texas Center for Superconductivity at the University of Houston (TcSUH).
PY - 2018/5/17
Y1 - 2018/5/17
N2 - The effect of controlling the c-axis alignment (mosaicity) to the cross-plane thermal transport in textured polycrystalline aluminum nitride (AlN) thin films is experimentally and theoretically investigated. We show that by controlling the sputtering conditions we are able to deposit AlN thin films with varying c-axis grain tilt (mosaicity) from 10° to 0°. Microstructural characterization shows that the films are nearly identical in thickness and grain size, and the difference in mosaicity alters the grain interface quality. This has a significant effect to thermal transport where a thermal conductivity of 4.22 W/mK vs. 8.09 W/mK are measured for samples with tilt angles of 10° vs. 0° respectively. The modified Callaway model was used to fit the theoretical curves to the experimental results using various phonon scattering mechanisms at the grain interface. It was found that using a non-gray model gives an overview of the phonon scattering at the grain boundaries, whereas treating the grain boundary as an array of dislocation lines with varying angle relative to the heat flow, best describes the mechanism of the thermal transport. Lastly, our results show that controlling the quality of the grain interface provides a tuning knob to control thermal transport in polycrystalline materials.
AB - The effect of controlling the c-axis alignment (mosaicity) to the cross-plane thermal transport in textured polycrystalline aluminum nitride (AlN) thin films is experimentally and theoretically investigated. We show that by controlling the sputtering conditions we are able to deposit AlN thin films with varying c-axis grain tilt (mosaicity) from 10° to 0°. Microstructural characterization shows that the films are nearly identical in thickness and grain size, and the difference in mosaicity alters the grain interface quality. This has a significant effect to thermal transport where a thermal conductivity of 4.22 W/mK vs. 8.09 W/mK are measured for samples with tilt angles of 10° vs. 0° respectively. The modified Callaway model was used to fit the theoretical curves to the experimental results using various phonon scattering mechanisms at the grain interface. It was found that using a non-gray model gives an overview of the phonon scattering at the grain boundaries, whereas treating the grain boundary as an array of dislocation lines with varying angle relative to the heat flow, best describes the mechanism of the thermal transport. Lastly, our results show that controlling the quality of the grain interface provides a tuning knob to control thermal transport in polycrystalline materials.
UR - http://hdl.handle.net/10754/627942
UR - https://pubs.acs.org/doi/10.1021/acsami.8b02899
UR - http://www.scopus.com/inward/record.url?scp=85047430824&partnerID=8YFLogxK
U2 - 10.1021/acsami.8b02899
DO - 10.1021/acsami.8b02899
M3 - Article
C2 - 29772174
SN - 1944-8244
VL - 10
SP - 20085
EP - 20094
JO - ACS Applied Materials & Interfaces
JF - ACS Applied Materials & Interfaces
IS - 23
ER -