Effectively tuning phonon transport across Al/nonmetal interfaces through controlling interfacial bonding strength without modifying thermal conductivity

Abstract

Tuning phonon transport across interfaces is crucial for optimizing thermal management of various microelectronics, where efficient heat dissipation and effective thermal insulation are essential for different devices. Previous strategies are either limited by the operating conditions or necessitate compromising the thermal dissipation performance of underlying substrates. Here, we propose an effective method to tune phonon transport across non-ideal realistic Al/nonmetal interfaces by modulating interfacial bonding strength, without altering the thermal conductivity of underlying substrates. We achieve up to a 3-fold increase in interfacial thermal conductance (G) through variations in deposition methods and surface pretreatments. Our non-destructive picosecond acoustic measurements reveal a strong correlation between G and acoustic transmission coefficient, confirming that the observed enhancement in G is primarily due to the larger interfacial bonding strength, facilitated by the contamination removal and covalent bond formation during sputtering deposition. Our measured temperature dependence of G suggests that the differing interfacial bonding strength mainly affects the transmission of low-frequency phonons. Moreover, we observe that the effective phonon transmission probability of non-ideal realistic Al/nonmetal interfaces exhibits remarkable substrate independence, revealing that, unlike commonly emphasized in previous studies, the similarity in phonon density of states (DOS) is not a necessary requirement for enhancing the phonon transport across these interfaces. Instead, interfacial bonding strength plays a more dominant role in governing G of non-ideal realistic interfaces. We also demonstrate the long-term stability of the enhanced G after extended storage and confirm the effectiveness of our methods over a temperature range of 80–500 K. Our findings advance the fundamental understanding of phonon transport across non-ideal realistic interfaces and should be useful in ongoing efforts for thermal management in microelectronics.