Thermal and mechanical modulation of interfacial thermal resistance in GaN/diamond heterostructures based on machine learning potentials

Heterogeneous integration of high-thermal-conductivity diamond with gallium nitride (GaN) represents a compelling paradigm to break through the thermal dissipation bottlenecks in high-power electronics. However, the intrinsic acoustic mismatch between GaN and diamond gives rise to a non-negligible interfacial thermal resistance (ITR). This ITR severely limits the heat dissipation efficiency. In this work, a high-fidelity neuroevolution potential (NEP) machine learning interatomic potential is developed. This potential demonstrates markedly superior predictive accuracy compared with the conventional Tersoff empirical potential. Driven by this validated framework, non-equilibrium molecular dynamics (NEMD) simulations are carried out across operational temperatures of 300–600 K and external compressive stresses of 0–8 GPa. These simulations systematically investigate the monotonic and coupled regulation laws governing the GaN/diamond ITR. NEMD simulations reveal that the ITR at 300 K ranges from 2.40 to 3.25 m 2 ·K·GW −1 across distinct interface configurations. These values are in close quantitative agreement with the theoretical prediction of the diffuse mismatch model (DMM). Crucially, C-N-bonded interfaces exhibit ITR values approximately 20% lower than their C-Ga-bonded counterparts. With increasing temperature, enhanced lattice anharmonicity increases the cross-interface phonon density of states (PDOS) overlap ratio by approximately 3.65% and raises the total phonon participation contribution (TPPC) by 5.72%. These combined effects result in a monotonic reduction in ITR. The modulation of ITR by external compressive stress is even more pronounced. At 8 GPa, the ITR precipitously drops below 2.10 m 2 ·K·GW −1 . This reduction is accompanied by increases in the PDOS overlap ratio and the TPPC of approximately 6.57% and 10.54%, respectively. Simulated HRTEM and HAADF-STEM characterizations provide direct atomistic-scale evidence that compressive stress effectively shortens the interfacial bond lengths and reinforces multi-body interatomic interactions. The thermo-mechanical coupled regulation mechanisms uncovered in this study provide essential theoretical guidance and novel design strategies for structural stress engineering and high-performance interfacial thermal optimization in GaN/diamond electronics.