Systematic Investigations on the Thermal Management Performance of Graphite Thin Films for High-Electron-Mobility Transistors

Self-heating is a severe problem for high-electron-mobility transistors (HEMTs). Graphene and thin graphite films are attractive candidates for heat spreader materials at the transistor level due to their ultrahigh in-plane thermal conductivity. However, a realistic and systematic simulation study of how they can improve the thermal management of HEMTs has not been carried out yet and is needed to push the method into practical use and realize industrialization. This study systematically investigated the effect of graphene and thin graphite films, and the most practical boundary condition in the simulations was primarily selected with comparisons. Then, the thermal properties consisting of thermal conductivity and interfacial thermal resistance (ITR) between graphite and other materials were fully investigated, which may bottleneck the actual improvement of the thermal management in applications. Our steady-state results indicated that the ITR between graphite and SiO2 determined the whole improvement in thermal management performance through the added graphite heat bridge. Subsequently, the transient thermal analysis was conducted on the HEMTs to explore the effect of graphene and thin graphite films under repeated joule heating pulses on a microsecond time scale, and we obtained the effect of graphene and thin graphite films on each heating and cooling process. Finally, based on all the results and analysis mentioned above, we can confirm that the graphite-based heat-spreader structures can still offer efficient heat dissipation under near-real conditions, thereby indicating ways of the optimization of HEMTs heat dissipation.