How mass disorder affects heat conduction in ternary amorphous alloys

Abstract

Thermal management is critical in devices that use amorphous semiconductors. Recent studies have revealed how size and mass disorder affect heat conduction, but the effects of more-extreme mass and lattice disorder are also relevant. Here, we report modal analysis of simulated samples of amorphous silicon alloyed with atoms of different-mass silicon to yield a ternary amorphous material. Although we expected the material with high degrees of mass disorder to show dramatic changes in thermal conductivity as the composition of the material changed, the thermal conductivity instead changed monotonically. Thus, we find that no peculiar thermal transport properties appear in ternary amorphous alloys with high degrees of mass disorder. Furthermore, we find that while delocalized propagating modes (propagons) explain nearly 30% of the overall thermal conductivity independent of the composition, the contribution of delocalized non-propagating modes (diffusons) is sensitive to the composition and tends to be the dominant mechanism behind heat conduction in ternary amorphous alloys.