Inelastic phonon transport across atomically sharp metal/semiconductor interfaces

Understanding thermal transport across metal/semiconductor interfaces is crucial for the heat dissipation of electronics. The dominant heat carriers in non-metals, phonons, are thought to transport elastically across most interfaces, except for a few extreme cases where the two materials that formed the interface are highly dissimilar with a large difference in Debye temperature. In this work, we show that even for two materials with similar Debye temperatures (Al/Si, Al/GaN), a substantial portion of phonons will transport inelastically across their interfaces at high temperatures, significantly enhancing interface thermal conductance. Moreover, we find that interface sharpness strongly affects phonon transport process. For atomically sharp interfaces, phonons are allowed to transport inelastically and interface thermal conductance linearly increases at high temperatures. With a diffuse interface, inelastic phonon transport diminishes. Our results provide new insights on phonon transport across interfaces and open up opportunities for engineering interface thermal conductance specifically for materials of relevance to microelectronics. Phonons are thought to transport elastically across most interfaces. Here, the authors show that a substantial portion of phonons transport inelastically, adding another heat conduction channel and enhancing thermal conductance across interfaces.

Automated summary

This study reveals that even for materials with similar Debye temperatures, a significant portion of phonons can transport inelastically across interfaces at high temperatures, greatly enhancing the interface thermal conductance. The sharpness of the interface strongly affects the phonon transport process. These findings provide new insights and opportunities for engineering interface thermal conductance in microelectronics materials.