Molecular dynamics study of the impact of coordination number on the thermal conductivity of amorphous Ga₂O₃

Gallium oxide (Ga₂O₃) has emerged as a promising ultra-wide bandgap semiconductor for next-generation power electronics and optoelectronic devices. However, the thermal transport properties of Ga₂O₃, particularly in its amorphous state, remain poorly understood, even though they are critically important for device reliability. In this work, we employed molecular dynamics simulations with a machine-learned neuroevolution potential (NEP) to investigate the structure-thermal property relationship between structure and thermal properties in a-Ga₂O₃ across a comprehensive density range (3.5–8.0 g/cm³). Through systematic analysis of radial distribution functions, angular distributions, and coordination environments, we identify two distinct structural transitions at 5.25 g/cm³ and 6.50 g/cm³, corresponding to the progressive transformation of Ga coordination from fourfold to sixfold coordination and O coordination from threefold to fourfold. Homogeneous nonequilibrium MD simulations coupled with spectral heat current analysis reveal that these structural changes induce sharp enhancements in thermal conductivity, mediated through simultaneous improvements in both propagons and diffusons. The increase in atomic coordination creates more direct atomic pathways while strengthening interatomic coupling, ultimately enabling a sixfold increase in thermal conductivity across the studied density range. Our findings establish fundamental structure-property relationships in a-Ga₂O₃ and suggest general design principles for thermal management in amorphous semiconductors undergoing coordination polyhedral transitions.