Study of the Lattice Thermal Conductivity of Janus In₂Ge₂S₆ and In₂Ge₂S₃Se₃ Bilayers

Abstract

In this paper, we investigate the lattice thermal conductivity of Janus In₂Ge₂S₆ and In₂Ge₂S₃Se₃ bilayers by solving the phonon Boltzmann transport equation using first-principles calculations. We found that this is mainly due to the fact that the frequencies at which larger gaps appear in the intermediate and high frequency optical branches of In₂Ge₂S₃Se₃ are smaller than those of In₂Ge₂S₆, which shifts the phonon dispersion curve of In₂Ge₂S₃Se₃ downward, which makes the overall phonon group velocity of In₂Ge₂S₃Se₃ material smaller than that of In₂Ge₂Se₆ material, and also due to the fact that In₂Ge₂S₃Se₃ soft bending in the finite layer thickness coupling and the tight connection of the in-plane acoustic modes, resulting in increased phonon-phonon scattering processes, shorter phonon relaxation times, and larger Grüneisen parameters indicating a stronger anharmonic In₂Ge₂S₃Se₃ structure, all these factors combined lead to a lattice thermal conductivity of In₂Ge₂S₃Se₃ smaller than the lattice thermal conductivity of In₂Ge₂S₆. At a temperature of 1000 K, the In₂Ge₂S₃Se₃ structure has a minimum lattice thermal conductivity of about 0.22 W/mK, and In₂Ge₂S₆ has a minimum lattice thermal conductivity of about 0.4 W/mK. Our results suggest that Janus In₂Ge₂S₆ and In₂Ge₂S₃Se₃ bilayers are potential for future thermal management of nanoelectronic devices and thermoelectric devices. two-dimensional materials.

Keywords:

• Two-dimensional materials
• First-principles calculations
• Lattice thermal conductivity

Disclosure Statement

No potential conflict of interest was reported by the author(s).