Multi-length scale electro-thermal simulations of GaN high electron mobility transistors

Overheating has largely limited the performance of GaN-based high electron mobility transistors (HEMTs) as high-power and high-frequency electronic devices. In this work, a multi-length scale simulation technique is developed and demonstrated in a 2D GaN-on-SiC HEMT. For the transistor region, coupled electron and phonon Monte Carlo (MC) simulations are used to address the phonon emission by hot electrons and phonon transport within the ~10 μm transistor region. Away from the transistor, conventional Fourier analysis is invoked so that heat transfer across the whole macroscale device can still be considered. Energy-dependent electron and phonon transport, either within a material or across an interface, can be incorporated into the simulation. Beyond 2D HEMTs, this technique can be applied to more complicated 3D devices for accurate prediction of device characteristic.