A research team led by Gao Peng at the International Center for Quantum Materials, School of Physics, Peking University, has developed a groundbreaking method to visualize interfacial phonon transport with unprecedented sub-nanometer resolution. These results, published in the journal Nature, uncover a tantalizing new understanding of how heat is transferred at the atomic level. These discoveries target material interfaces that are critical for developing high-performing electronic devices. The full peer-reviewed study is published under DOI 10.1038/s41586-025-09108-6.
The study explores how phonons, the quantized modes of lattice vibrations that transport heat in solids, interact in complex manner. This process is still not well understood – primarily due to the fact that measuring temperature at these extremely small scales is incredibly difficult. This investigation does an excellent job of explaining how heat travels through materials, giving us a deeper understanding of how manipulating phonons can assist in controlling heat.
Phonon Transport Dynamics Revealed
Working with a team of researchers, Gao Peng used cutting-edge electron microscopy to study. They were especially interested in studying phonon transport dynamics across the AlN/SiC interface. Instead, the group discovered a striking temperature rise of 10–20 K over only ~2 nanometers. This breakthrough reveals a remarkable temperature slope of 180 K/μm. This remarkable temperature rise demonstrates the extraordinary thermal resistance that can occur at material interfaces.
The interfacial thermal resistance was unexpectedly large. It was found to be ~30-70× better than bulk AlN or SiC. A comparable temperature decrease in traditional bulk materials would require a depth of tens to hundreds of nanometers. Such discoveries highlight the need for an improved fundamental understanding of phonon transport in further advancing thermal management strategies in electronic devices.
“Measuring temperature at the nanoscale is already an extremely challenging task. This paper goes beyond that and gives us an insight into how heat flows across interfaces at these very small scales, and the phonon interactions that mediate such processes. The materials studied here are also important as there is interest in their use on high-power electronic devices, where thermal management is critical.” – Stuart Thomas, senior editor of Nature
Challenges in Nanoscale Measurement
Yet measuring temperature at the nanoscale comes with many challenges. These techniques are far from the spatial resolution needed for technologies that are working below 10 nanometers. Gao Peng’s research group addressed these limitations directly. Importantly, they leveraged state-of-the-art microscopy techniques to visualize phonon-mediated heat transport with remarkable resolution.
The spatially resolved study found nonequilibrium phonon states over a length scale > 3 nm from the AlN/SiC interface. These states were identified based on their clear deviation from the expected Bose-Einstein distribution. This result deepens our knowledge of heat transport in nanometric materials. In addition, it opens the door for continued development of thermal management technologies that are key to enabling high-power electronics.
Implications for Future Technologies
The real-world implications of this research go far beyond ivory tower curiosity. As the demand for smaller, lighter, and higher-performance electronic devices continues to grow, the need for superior thermal management solutions is critical. The ability to visualize and understand phonon-mediated heat transport at such fine scales may lead to innovations in material design and engineering.
As electronic communications technology becomes increasingly miniaturized and powerful, to maintain their performance and longevity, we need to be able to maximize their heat dissipation. Gao Peng’s research group provides important guidance that could change the way materials are developed for high-power applications. These new materials will not only dissipate heat, but keep their performance intact.
