Atomic-scale probing of heterointerface phonon bridges in nitride semiconductor

Significance As high-power devices approach nanoscale, interface thermal conductance (ITC) becomes a bottleneck to govern the device performance, which is dominated by the interface phonons. In order to gain insights into engineering ITC, here we measure the local phonons across AlN/Si and AlN/Al interfaces by using atomically resolved vibrational electron energy-loss spectroscopy. We find that the dominant types of interface phonons for ITC are very different in these two systems and demonstrate the ability to correlate the measured interface phonons with ITC at atomic scale. Our study reveals the underlying mechanism of ITC and provides useful insights for thermal management in these practically important semiconductors.