Thermal conductivity modulation under strain gradients in III–V semiconductors

With the continued miniaturization and power scaling of electronic devices, thermal management in III–V semiconductors has become a critical bottleneck to further performance improvement. In practical architectures, mechanical deformation and packaging processes inevitably introduce inhomogeneous strain fields; however, how such strain gradients regulate phonon transport and lead to material-dependent thermal responses remains poorly understood. Here, using AlN, GaN, and InN nanoribbons as model systems, we uncover the intrinsic mechanism linking strain gradients to thermal conductivity modulation. We develop a neuroevolution potential capable of accurately describing lattice dynamics under bending-induced strain gradients, enabling reliable non-equilibrium molecular dynamics simulations under identical deformation conditions. Strain gradients are found to universally suppress thermal conductivity by broadening the phonon spectrum, narrowing the acoustic–optical (ao) phonon gap, and activating additional phonon–phonon scattering channels. Remarkably, the magnitude of thermal-conductivity reduction differs significantly among the three materials: GaN and InN exhibit far stronger suppression than AlN. Combined analyses of phonon density of states, spectral heat current, phonon dispersion, and scattering rates reveal that this contrast originates from their distinct intrinsic ao gaps determined by atomic mass. For systems with larger intrinsic ao gaps, strain-induced narrowing more effectively relaxes energy-conservation constraints, dramatically expanding the three-phonon phase space. These results establish a quantitative link among atomic mass, ao gap regulation, and strain-gradient-driven thermal conductivity modulation. Beyond revealing a previously unresolved strain–phonon–thermal transport coupling mechanism, this work provides a physics-based design framework for precision thermal management through atomic-mass engineering and strain-gradient control in next-generation high-performance electronic devices.