Reversible Electric-Field-Induced Changes in the Thermal Resistance of Hexagonal Boron Nitride

Understanding the behavior of ultrawide-bandgap (UWBG) materials under high electric fields is essential for advancing next-generation power electronics. While electrical degradation processes have been widely studied, the influence of high electric fields on thermal transport remains largely unexplored. Here, we report the first experimental measurements of changing thermal resistance under an applied electric field in a UWBG material, using single-crystalline hexagonal boron nitride (h-BN) as a model system. We observe substantial, and sometimes reversible, changes in thermal resistance during prolonged exposure to a strong DC electric field. These results reveal a previously unrecognized sensitivity of phonon transport to high-field electrical stressing and show that thermal resistance can serve as a sensitive probe of electric-field-induced material evolution that remains undetected by conventional electrical characterization. More broadly, this work establishes thermal transport measurements as a powerful tool for investigating high-field phenomena in UWBG materials.