Using Mosaicity to Tune Thermal Transport in Polycrystalline Aluminum Nitride Thin Films
| Autor: | Anastassios Mavrokefalos, Shivkant Singh, Haiding Sun, Ronghui Lin, Shahab Shervin, Jae-Hyun Ryou, Jie Chen, Xiaohang Li, Milad Yarali, Kuang-Hui Li |
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| Rok vydání: | 2018 |
| Předmět: |
010302 applied physics
Materials science Phonon scattering 02 engineering and technology Nitride 021001 nanoscience & nanotechnology 01 natural sciences Grain size Mosaicity Thermal conductivity 0103 physical sciences General Materials Science Grain boundary Crystallite Composite material Thin film 0210 nano-technology |
| Zdroj: | ACS applied materialsinterfaces. 10(23) |
| ISSN: | 1944-8252 |
| Popis: | 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 vs 8.09 W/mK are measured for samples with tilt angles of 10° versus 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. |
| Databáze: | OpenAIRE |
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