A comprehensive study of phonon thermal transport in 2D IV-VI semiconductors MX (M = Ge, Sn; X = S, Se)

Abstract

Based on the density functional theory and first-principles calculations we conducted a comprehensive study of the thermal transport properties of dynamical stable 2D IV-VI semiconductors MX (M = Ge, Sn; X = S, Se). The calculated lattice thermal conductivity is anisotropic, and the larger value of aaxis can be attributed to the higher phonon group velocity, besides, the optical modes of SnSe made a great contribution to the lattice thermal conductivity as a result of the most optical modes are located in the low frequency range. In addition, the lattice thermal conductivity of GeX is generally larger than that of SnX, which can be also attributed to the larger phonon group velocity. Our research reveals the thermal transport characteristics of 2D MX and points out the difference in lattice thermal conductivity of GeX and SnX.