Generation of interfacial phonon modes and their contribution to thermal transport across the GaN/ZnO interface

Interfacial phonon modes are pivotal to thermal transport across interfaces and are essential for optimizing heat dissipation in micro- and nanoscale devices. In this work, we investigate the generation mechanism of interfacial phonon modes and their contribution to thermal transport across the GaN/ZnO interface using atomic simulations. Our results identify two distinct types of interfacial phonon modes: additional emerging modes and enhanced pristine bulk modes, which are distributed on each side of the interface. By using an extended wavelet transform approach, we demonstrate that phonon polarization possesses a pronounced alignment with the orientation of covalent bonds at the interface, which elucidates their origin in coupled atomic vibrations extending across the interface. As a result, we find that only the longitudinal interfacial phonon modes are present near the GaN/ZnO interface with zigzag edges. Furthermore, we reveal that these unique characteristics enable the interfacial phonon modes to significantly enhance interfacial thermal conductance through a dual mechanism that simultaneously opens inelastic scattering channels and reinforces elastic ones. This study provides a fundamental understanding of interfacial thermal transport and phonon physics at the microscopic level, which might offer valuable insight to advanced thermal management in device applications.