Thermal simulation of high power GaN-on-diamond substrates for HEMT applications

Abstract A three-dimensional thermal simulation for analysis of heat dissipation of AlGaN/GaN HEMT with diamond substrates is presented by the finite element method. The model accounts for the nonlinear thermal conductivities of GaN and diamond materials by employing Kirchhoff's transformation with the aim to improve calculation accuracy. In addition, the geometric parameters of AlGaN barrier, heat sources, and interfacial thermal resistance are considered and treated appropriately in our numerical analysis. We investigate the temperature distribution and heat spreading paths of the intra-chip, and those results indicate that the thickness of epitaxial layers and interfacial thermal resistance have certain influence on the magnitude of the junction temperature, especially interfacial thermal resistance of which the effect is as high as 19 K per 10 m 2  K/GW due to the capacity of horizontal and vertical heat spreading in the near-junction region. The analytical heat dissipation is necessary for providing helpful insight into the dominant factors in the formation of highly localized hotspots in the near-junction region.