Ultrahigh Interfacial Thermal Conductance across GaN/BAs Interfaces via Atomic-Level Engineering.

The integration of gallium nitride (GaN) with ultrahigh-thermal-conductivity boron arsenide (BAs) substrates represents a promising pathway for developing next-generation high-power devices. The heat dissipation capability of such integrated systems is fundamentally governed by thermal transport across GaN/BAs interfaces, and buffer layers such as Al2O3 have been widely adopted to accommodate lattice mismatch and facilitate heterointegration. However, the atomic-scale structural factors governing thermal transport across GaN/BAs interfaces remain unclear, limiting further improvements in interfacial thermal conductance. Herein, we propose an atomic-scale interfacial structural-uniformity strategy for engineering ultrahigh thermal conductance across GaN/BAs interfaces using molecular dynamics simulations augmented by machine-learning interatomic potentials. We show that interfacial structural uniformity plays a more important role than individual bond strength in determining thermal transport across the investigated GaN/BAs interfaces. For instance, the As-N-terminated coherent interface exhibits the highest interfacial structural uniformity and achieves an ultrahigh interfacial thermal conductance of approximately 2000 MW·m- 2·K- 1, representing a nearly eightfold enhancement over the experimentally reported Al2O3-mediated interface (250 MW·m-2·K-1). Finite-element analysis indicates that this atomic-scale optimization directly translates into device-scale performance, leading to a substantial improvement in overall heat dissipation efficiency. These findings suggest that engineering interfacial structural uniformity offers a promising strategy for achieving high-efficiency thermal management in next-generation high-power electronic devices.