Depth-resolved thermal conductivity of HFCVD diamond films via square-pulsed thermometry

The integration of high-thermal-conductivity diamond films onto silicon carbide (SiC) substrates offers a promising pathway for thermal management in high-power electronic devices. Here, we investigate the depth-dependent thermal conductivity of a ∼5 μm-thick diamond film grown on SiC by hot filament chemical vapor deposition (HFCVD) using square-pulsed source thermometry. Electron backscatter diffraction and transmission electron microscopy reveal pronounced grain coarsening from the nucleation interface to the film surface. By combining frequency-dependent thermal penetration with a depth-resolved thermal transport model, we quantitatively reconstruct the thermal conductivity profile. The thermal conductivity increases sharply from ∼60 W m−1 K−1 near the nucleation region to ∼200 W m−1 K−1 at the surface, directly reflecting the underlying microstructural evolution. These results provide a physically grounded understanding of graded heat transport in HFCVD diamond and offer practical guidance for engineering diamond-based thermal management layers for next-generation power devices.