Strain engineering of phonon thermal transport properties in monolayer 2H-MoTe.

The effect of strain on the phonon properties such as phonon group velocity, phonon anharmonicity, phonon lifetime, and lattice thermal conductivity of monolayer 2H-MoTe is studied by solving the Boltzmann transport equation based on first principles calculations. The phonon thermal transport properties of the unstrained monolayer 2H-MoTe are compared to those of the strained case under different biaxial tensile strains. One of the common features of two-dimensional materials is the quadratic nature near the Γ point of the out-of-plane phonon flexural mode that disappears by applying tensile strain. We find that the lattice thermal conductivity of the monolayer 2H-MoTe is very sensitive to strain, and the lattice thermal conductivity is reduced by approximately 2.5 times by applying 8% biaxial tensile strain due to the reduction in phonon group velocities and phonon lifetime. We also analyze how the contribution of each mode to lattice thermal conductivity changes with tensile strain. These results highlight that tensile strain is a key parameter in engineering phonon thermal transport properties in monolayer 2H-MoTe.