Effect of crystallinity and thickness on thermal transport in layered PtSe2
We present a comparative investigation of the influence of crystallinity and film thickness on the acoustic and thermal properties of layered PtSe films of varying thickness (1-40 layers) using frequency-domain thermo-reflectance, low-frequency Raman, and pump-probe coherent phonon spectroscopy. We...
| Autores: | , , , , , , , , , , , , , |
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| Tipo de recurso: | artículo |
| Fecha de publicación: | 2022 |
| País: | España |
| Institución: | Universitat Autònoma de Barcelona |
| Repositorio: | Dipòsit Digital de Documents de la UAB |
| Idioma: | inglés |
| OAI Identifier: | oai:ddd.uab.cat:266323 |
| Acceso en línea: | https://ddd.uab.cat/record/266323 https://dx.doi.org/urn:doi:10.1038/s41699-022-00311-x |
| Access Level: | acceso abierto |
| Palabra clave: | Cristallinity Cross planes Film-thickness Frequency domains Low-frequency Raman Pump probe Raman probe Thermal transport Thermoreflectance Varying thickness |
| Sumario: | We present a comparative investigation of the influence of crystallinity and film thickness on the acoustic and thermal properties of layered PtSe films of varying thickness (1-40 layers) using frequency-domain thermo-reflectance, low-frequency Raman, and pump-probe coherent phonon spectroscopy. We find ballistic cross-plane heat transport up to ~30 layers PtSe and a 35% reduction in the cross-plane thermal conductivity of polycrystalline films with thickness larger than 20 layers compared to the crystalline films of the same thickness. First-principles calculations further reveal a high degree of thermal conductivity anisotropy and a remarkable large contribution of the optical phonons to the thermal conductivity in bulk (~20%) and thin PtSe films (~30%). Moreover, we show strong interlayer interactions in PtSe, short acoustic phonon lifetimes in the range of picoseconds, an out-of-plane elastic constant of 31.8 GPa, and a layer-dependent group velocity ranging from 1340 ms in bilayer to 1873 ms in eight layers of PtSe. The potential of tuning the lattice thermal conductivity of layered materials with the level of crystallinity and the real-time observation of coherent phonon dynamics open a new playground for research in 2D thermoelectric devices and provides guidelines for thermal management in 2D electronics. |
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