The Role of Interfacial Electronic Properties on Phonon Transport in Two-Dimensional MoS on Metal Substrates.

We investigate the role of interfacial electronic properties on the phonon transport in two-dimensional MoS adsorbed on metal substrates (Au and Sc) using first-principles density functional theory and the atomistic Green's function method. Our study reveals that the different degree of orbital hybridization and electronic charge distribution between MoS and metal substrates play a significant role in determining the overall phonon-phonon coupling and phonon transmission. The charge transfer caused by the adsorption of MoS on Sc substrate can significantly weaken the Mo-S bond strength and change the phonon properties of MoS, which result in a significant change in thermal boundary conductance (TBC) from one lattice-stacking configuration to another for same metallic substrate. In a lattice-stacking configuration of MoS/Sc, weakening of the Mo-S bond strength due to charge redistribution results in decrease in the force constant between Mo and S atoms and substantial redistribution of phonon density of states to low-frequency region which affects overall phonon transmission leading to 60% decrease in TBC compared to another configuration of MoS/Sc. Strong chemical coupling between MoS and the Sc substrate leads to a significantly (∼19 times) higher TBC than that of the weakly bound MoS/Au system. Our findings demonstrate the inherent connection among the interfacial electronic structure, the phonon distribution, and TBC, which helps us understand the mechanism of phonon transport at the MoS/metal interfaces. The results provide insights for the future design of MoS-based electronics and a way of enhancing heat dissipation at the interfaces of MoS-based nanoelectronic devices.