Thermal conductivity in MoSi₂N₄(MoN)ₙ: Insights into phonon scattering and transport

Abstract

As nanoelectronics devices continue to shrink in size and increase in integration, managing heat effectively becomes essential for maintaining their stable operation. Two-dimensional (2D) materials, characterized by their superior thermal conductivity, and mechanical flexibility are considered excellent options for thermal management purposes. This study explores the thermal transport properties of 2D sandwich material MoSi₂N₄(MoN)_n(n = 0–4) using Density Functional Theory and Neural Network Potential. We found that adding a layer of (MoN) on MoSi₂N₄ to form MoSi₂N₄(MoN)₁ results in a significant decrease in thermal conductivity. We have provided a reasonable explanation for this phenomenon, discovering that it is due to the addition of a layer of (MoN) significantly shortening the phonon lifetime and the average free path of phonons. Furthermore, the addition of a layer of (MoN) leads to an increase in anharmonicity. However, when we continue to add more layers of (MoN), we find that the thermal conductivity no longer shows a significant decrease, but only a slight reduction. This indicates that as more layers of (MoN) are added, the scattering mechanisms reach saturation. These findings reveal the unique thermal behavior of 2D sandwich materials and offer valuable insights for their application in heat energy utilization and thermal management technologies.