期刊
ACS APPLIED MATERIALS & INTERFACES
卷 10, 期 23, 页码 20085-20094出版社
AMER CHEMICAL SOC
DOI: 10.1021/acsami.8b02899
关键词
thermal conductivity tuning; mosaicity; AlN; dislocations; grain interface
资金
- University of Houston
- KAUST Baseline [BAS/1/1664-01-01]
- KAUST CRG [URF/1/3437-01-01]
- King Abdullah University of Science and Technology (KAUST) [OSR-2017-CRG6-3437.02]
- Texas Center for Superconductivity at the University of Houston (TcSUH)
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 degrees to 0 degrees. 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 vs 8.09 W/mK are measured for samples with tilt angles of 10 degrees versus 0 degrees 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.
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