Phonon thermal conductivity of monolayer MoS2: A comparison with single layer graphene

We investigate the size and edge roughness dependence on thermal conductivity of monolayer MoS2 (MLMoS2) by phonon Boltzmann transport equation combined with relaxation time approximation. The relative contribution of spectral phonons to thermal conductivity is explored, and we compared the characteristics of phonon transport with those in single layer graphene (SLG), which is a representative two-dimensional material. Quite different from SLG, because of the ultra-short intrinsic phonon mean free path, the thermal conductivity of MLMoS2 ribbons is size and roughness insensitive. The LA phonons have the major contribution to thermal conductivity of MLMoS2, and the ZA phonons in MLMoS2 have high relative contribution to thermal conductivity. The relative contribution to thermal conductivity from both high frequency and low frequency phonons in MLMoS2 is lower than that in SLG. The underlying mechanism of these distinct characteristics results from the different phonon dispersions and anharmonic characteristic between MLMoS2 and SLG.