Molecular dynamics study of thermal transport in amorphous silicon carbide thin film

Abstract

The emergence of amorphous silicon carbide (a-SiC) thin film based photovoltaic applications has provoked great interest in its physical properties. In this work, we report the first comprehensive study of thermal transport in the a-SiC thin film from 10 nm to 50 nm under various conditions using empirical molecular dynamic (MD) simulations. The thermal conductivity increases from 1.38 to 1.75 W m⁻¹K⁻¹ as temperature increases from 100 K to 1100 K. A similar increase in the thermal conductivity from 1.4 to 2.09 W m⁻¹K⁻¹ is obtained with densities from 2.7 to 3.24 g cm⁻³. Besides, a slight increase in the thermal conductivity (15%) with calculation domain from 10 nm to 50 nm is observed, indicating that the size dependence of thermal transport also exists in nanoscale amorphous structures. For the physical interpretation of simulation results, the phonon mean free path (MFP) and specific heat are calculated, which are responsible for the temperature dependence of the thermal conductivity. The phonon group velocity is the key factor for the change in thermal conductivity with density. The results also show that the phonon MFP decreases rapidly with temperature and is subject to the Matthiessen's rule.