Fig. 5: The finite element models (FEM) models and the effective thermal conductivity (κ) for different percentages of BAs and GaN.

a The FEM model with 50% BAs and 50% GaN, and the multiscale Schematic including FEM, molecular dynamics (MD), and density functional theory (DFT). b, c The temperature profile and the distribution of heat flux at the typical size of 1 μm. d The effective κ of different proportion BAs and GaN models with respect to the grain size. The distribution of heat flux of 40% BAs/60% GaN, and 60% BAs/40% GaN are shown as inset. The colored ellipse marks the turning point of the effective κ with the increasing grain size.