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 Al 2 O 3 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 Al 2 O 3 ‐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.