Lattice Dynamics Study on the Thermal Conduction Properties of Single Atomic Layer Films (II)—Numerical Calculations and Analysis on the Results

摘要

Based on the formulas derived previously by the authors, the variation of the phonon line width, phonon free path, the contribution of phonon to thermal conductivity with its wave vector are calculated. The results show that the phonon with a shorter wave vector, or with a lower frequency, has a longer free path and a greater contribution to the thermal conductivity. When the size of the film increases, the more phonon free path distribution is concentrated in the low wave vector region, the phonon free path in the low wave vector region is larger, and the contribution of the short wave vector phonon, that is the low frequency phonon, to the thermal conductivity of the film is bigger. The larger the size of the film, the larger the thermal conductivity, and when the size N exceeds 40 lattice constants, there is a linear relationship between the thermal conductivity and logN. When the size tends to infinity, the thermal conductivity tends to diverge, so single atomic layer film with large size has excellent heat dissipation performance.