Spectral Thermal Spreading Resistance of Wide-Bandgap Semiconductors in Ballistic-Diffusive Regime

To develop efficient thermal management strategies for wide-bandgap (WBG) semiconductor devices, it is essential to have a clear understanding of the heat transport process within the device and accurately predict the junction temperature. In this article, we use the phonon Monte Carlo (MC) method with the phonon dispersion of several typical WBG semiconductors, including GaN, SiC, AlN, and beta-Ga2O3, to investigate the thermal spreading resistance in a ballistic-diffusive regime. This work shows that when compared with Fourier's law-based predictions, the increase in the thermal resistance caused by the ballistic effects is strongly related to the phonon dispersion. Based on the model derived under the gray-medium approximation and the results of dispersion MC, we obtained a thermal resistance model that can well address the issues of thermal spreading, ballistic effects, and the influence of phonon dispersion. The model can be easily coupled with finite-element method (FEM)-based thermal analysis and applied to different materials. This article can provide a clearer understanding of the influence of phonon dispersion on the thermal transport process, and it can be useful for the prediction of junction temperatures and the development of thermal management strategies for WBG semiconductor devices.