Thermal Conductivity of Amorphous and Crystalline SiO2 Nano-films from Molecular Dynamics Simulations

Normal thermal conductivity of amorphous and crystalline SiO2 nano-films is calculated by nonequilibrium molecular dynamics (NEMD) simulations in the temperature range from 100 to 700K and thicknesses from 2 to 6nm. The calculated temperature and thickness dependences of thermal conductivity are in good agreement with previous literatures. In the same thickness, higher thermal conductivity is obtained for crystalline SiO2 nano-films. And more importantly, for amorphous SiO2 nano-films, thickness can be any direction of x, y, z-axis without effect on the normal thermal conductivity, for crystalline SiO2 nano-films, the different thickness directions obtain different thermal conductivity results. The different results of amorphous and crystalline SiO2 nano-films simply show that film thickness and grain morphology will cause different effects on thermal conductivity.