期刊
NANOSCALE
卷 8, 期 6, 页码 3760-3767出版社
ROYAL SOC CHEMISTRY
DOI: 10.1039/c5nr08231e
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- Hong Kong General Research Fund [152140/14E]
- Hong Kong Polytechnic University [1-99QP]
- National Natural Science Foundation of China [51271157]
- U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Materials Sciences and Engineering Division
- National Energy Research Scientific Computing Center (NERSC), a DOE Office of Science User Facility - Office of Science of the U. S. Department of Energy [DE-AC02-05CH11231]
Based on first principles calculations and self-consistent solution of the linearized Boltzmann-Peierls equation for phonon transport approach within a three-phonon scattering framework, we characterize lattice thermal conductivities k of freestanding silicene, germanene and stanene under different isotropic tensile strains and temperatures. We find a strong size dependence of k for silicene with tensile strain, i.e., divergent k with increasing system size; however, the intrinsic room temperature k for unstrained silicene converges with system size to 19.34 W m(-1) K-1 at 178 nm. The room temperature k of strained silicene becomes as large as that of bulk silicon at 84 mu m, indicating the possibility of using strain in silicene to manipulate k for thermal management. The relative contribution to the intrinsic k from out-of-plane acoustic modes is largest for unstrained silicene, similar to 39% at room temperature. The single mode relaxation time approximation, which works reasonably well for bulk silicon, fails to appropriately describe phonon thermal transport in silicene, germanene and stanene within the temperature range considered. For large samples of silicene, k increases with tensile strain, peaks at similar to 7% strain and then decreases with further strain. In germanene and stanene, increasing strain hardens and stabilizes long wavelength out-of-plane acoustic phonons, and leads to similar k behaviors to those of silicene. These findings further our understanding of phonon dynamics in group-IV buckled monolayers and may guide transfer and fabrication techniques for these freestanding samples and engineering of k by size and strain for applications of thermal management and thermoelectricity.
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