Heat Transfer Mechanism in a-Si and a-Si:H

Disordered solids are important materials to study because of their broad applications in technologies like thin-film transistors (TFT), solar cells and etc. They also have a scientifically significance due to their complexity and lack of order and periodicity. One of the long-standing issues in this class of solids is understanding the nature of heat transport in these solids. The common model of phonon gas breaks down for these materials. Therefore, many theories have formed around explaining the physics of these materials.
In this study, we used molecular dynamics simulations to investigate the thermal transport in amorphous silicon. We also looked into the hydrogenated amorphous silicon and microscopically investigated the effect of hydrogen doping in a-Si. We have also studied the evolution of the structures as the hydrogen content changes in a-SiH.
Our results suggest that hydrogenated amorphous silicon can demonstrate fundamentally different capabilities compared to a-Si. Thermal conductivity, calculated using Green-Kubo formula, shows that hydrogens can increase the thermal conductivity. We also separated the effect of hydrogen atoms and silicon atoms to fathom the role of hydrogen atoms. Most of our results are compared well with prior works in this area and can be extended by measuring the modal contributions to thermal conductivity.