The 10th Asian Symposium on Computational Heat Transfer and Fluid Flow ( ASCHT2025)

Due to lattice mismatch and thermal expansion induced by heterostructure epitaxial growth, inhomogeneous strain inevitably exists between adjacent layers in practical devices. Inhomogeneous strain has been proposed as a novel strategy for thermal conductivity modulation. However, experimental and theoretical investigations into strain-gradient-modulated thermal conductivity remain limited, particularly regarding the systematic understanding of how phonon spectrum broadening effects govern thermal transport regulation in semiconductor chip  materials under strain gradient fields. To accurately investigate thermal transport properties under inhomogeneous strain conditions, the neuroevolution potential (NEP) is developed specifically for AlN, GaN, and InN systems with strain gradient effects. The study shows that as the strain gradient increases, the suppressing effect of non-uniform strain on thermal conductivity becomes more pronounced, with a 4% non-uniform strain reducing the thermal conductivity of GaN by nearly 20%. The fundamental origin of this phenomenon lies in the strain gradient-induced modification of the phonon density of states, resulting in significant phonon spectrum broadening. These changes simultaneously suppress the acoustic-optical (AO) gap and intensify phonon-phonon scattering processes. Our findings not only offer a new perspective on how heat transfer can be dynamically modulated in semiconductor chip materials, but also provide crucial insights into enhancing thermal performance in devices.

Inhomogeneous strain; Neuroevolution potential; Semiconductor; Thermal conductivity