Thermal conductivity of hexagonal Si and hexagonal Si nanowires from first-principles
| Autor: | Xavier Cartoixà, Hugo Aramberri, Juan Antonio Seijas-Bellido, Riccardo Rurali, Martí Raya-Moreno |
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| Rok vydání: | 2017 |
| Předmět: |
Materials science
Physics and Astronomy (miscellaneous) Condensed matter physics Phonon Nanowire Lonsdaleite Diamond 02 engineering and technology engineering.material 021001 nanoscience & nanotechnology 01 natural sciences Boltzmann equation Condensed Matter::Materials Science symbols.namesake Thermal conductivity Computational chemistry 0103 physical sciences symbols engineering Hexagonal lattice 010306 general physics 0210 nano-technology Raman spectroscopy |
| Zdroj: | Applied Physics Letters. 111:032107 |
| ISSN: | 1077-3118 0003-6951 |
| DOI: | 10.1063/1.4985278 |
| Popis: | We calculate the thermal conductivity, κ, of the recently synthesized hexagonal diamond (lonsdaleite) Si using first-principles calculations and solving the Boltzmann Transport Equation. We find values of κ which are around 40% lower than in the common cubic diamond polytype of Si. The trend is similar for [111] Si nanowires, with reductions of the thermal conductivity that are even larger than in the bulk in some diameter range. The Raman active modes are identified, and the role of mid-frequency optical phonons that arise as a consequence of the reduced symmetry of the hexagonal lattice is discussed. We also show briefly that popular classic potentials used in molecular dynamics might not be suited to describe hexagonal polytypes, discussing the case of the Tersoff potential. |
| Databáze: | OpenAIRE |
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