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

TL;DR

This paper investigates the thermal spreading resistance in wide bandgap semiconductors using phonon Monte Carlo simulations, revealing how ballistic effects and phonon dispersion influence heat transport and device temperature predictions.

Contribution

It introduces a thermal resistance model that incorporates phonon dispersion and ballistic effects, enhancing thermal analysis accuracy for wide bandgap semiconductors.

Findings

Ballistic effects significantly increase thermal resistance compared to Fourier's law.

Phonon dispersion strongly influences thermal spreading resistance.

The proposed model aligns well with dispersion MC results and can be integrated with FEM.

Abstract

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 paper, we used the phonon Monte Carlo (MC) method with the phonon dispersion of various typical WBG semiconductors, including GaN, SiC, AlN, and \ce{\beta-Ga_2O_3}, to investigate the thermal spreading resistance in a ballistic-diffusive regime. It was found that when compared with Fourier's law-based predictions, the increase in the thermal resistance caused by ballistic effects was strongly related to different phonon dispersions. Based on the model deduced 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 and ballistic effects, and the influences of phonon dispersion. The model can be easily coupled with FEM based thermal analysis and applied to different materials. This paper can provide a clearer understanding of the influences 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.