Depth-Resolved Thermal Conductivity of HFCVD Diamond Films via Square-Pulsed Thermometry

TL;DR

This study measures the depth-dependent thermal conductivity of HFCVD diamond films on SiC, revealing microstructural influences on heat transport crucial for thermal management in power electronics.

Contribution

It introduces a method combining frequency-dependent thermal penetration with a depth-resolved model to quantify the microstructure-driven thermal conductivity profile.

Findings

Thermal conductivity increases from ~60 to ~200 W/m·K from the nucleation interface to the surface.

Microstructural evolution correlates with the sharp increase in thermal conductivity.

Provides insights for engineering diamond layers in high-power electronic devices.

Abstract

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 {\mu}m-thick diamond film grown on SiC by hot-filament chemical vapor deposition (HFCVD) using square-pulsed source (SPS) thermometry. Electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) 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.