How mass disorder affects heat conduction in ternary amorphous alloys

Tatsuki Ichikawa,Emi Minamitani,Takuma Shiga,Yuzo Shigesato,Makoto Kashiwagi

doi:10.1063/5.0051285

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.

Highlights

Amorphous semiconductors are essential in solar cells1,2 and microelectronics,3,4 and such devices require precise thermal management to ensure reliable performance
Giri et al.14 revealed that bond disorder makes a negligible contribution to the reduced thermal conductivity of a-Si1−xGex and mass disorder dominates the reduction, which is because interatomic interactions of Si atoms are transferable to those of Ge atoms
Norouzzadeh et al.16 investigated the dependence of thermal conductivity on temperature for a-Si, a-Ge, and a-Si0.8Ge0.2 in the temperature range from 300 to 1400 K, and they found that the thermal conductivities of a-Si and a-Ge are sensitive to temperature, while the thermal conductivity of a-Si0.8Ge0.2 is only weakly affected by temperature due to mass disorder

Summary

Introduction

Amorphous semiconductors are essential in solar cells and microelectronics, and such devices require precise thermal management to ensure reliable performance. With the development of the Allen–Feldman (AF) theory, several studies of heat conduction have revealed characteristic heat carriers, spectral transport properties, and size effects.8–12 With these developments, the modal analysis of thermal transport in amorphous materials has become accessible and mature.. Giri et al. revealed that bond disorder makes a negligible contribution to the reduced thermal conductivity of a-Si1−xGex and mass disorder dominates the reduction, which is because interatomic interactions of Si atoms are transferable to those of Ge atoms.. Giri et al. revealed that bond disorder makes a negligible contribution to the reduced thermal conductivity of a-Si1−xGex and mass disorder dominates the reduction, which is because interatomic interactions of Si atoms are transferable to those of Ge atoms.20,21 They found that size effects are present even in amorphous alloys. Norouzzadeh et al. investigated the dependence of thermal conductivity on temperature for a-Si, a-Ge, and a-Si0.8Ge0.2 in the temperature range from 300 to 1400 K, and they found that the thermal conductivities of a-Si and a-Ge are sensitive to temperature, while the thermal conductivity of a-Si0.8Ge0.2 is only weakly affected by temperature due to mass disorder

Methods

Results

Conclusion