The Impact of Noncontinuum Thermal Transport on the Temperature of AlGaN/GaN HFETs

The effects of power density and heat generation zone size on the hotspot temperature of AlGaN/GaN HFET devices were predicted using an electrothermal modeling approach. The thermal response was modeled using a multiscale model that accounted for ballistic-diffusive phonon transport effects in the heat generation zone near the gate and diffusive transport effects outside of this zone. The Joule heating distribution was calculated using a hydrodynamic model in Sentaurus Device. The hotspot temperatures at different biasing conditions were determined using the multiscale thermal model and compared with a fully diffusive transport model. The results show that the hotspot temperature is higher when ballistic-diffusive transport effects are considered and this difference increases with increasing power density in the AlGaN/GaN HFETs.