Strain Effect Analysis on Thermal Conductivity of Ge Thin Films

The effects of strains on the thermal conductivity of Ge thin films were studied by nonequilibrium molecular dynamics (NEMD) simulations. The results show that the strains have an appreciable influence on the thermal conductivity of Ge thin films. The thermal conductivity decreases as the tensile strain increases and increases as the compressive strain increases, because of the decrease in the phonons velocities and the surface reconstructions. Meanwhile, a theoretical calculation based on Modified-Callaway model under different strains was performed to verify our NEMD simulation results. We find that the theoretical results closely match the molecular dynamics results. The theoretical analysis reveals that the contributions of the relaxation time on strains are very important to the thermal conductivity of Ge thin films.