Electrothermal simulation of the self-heating effects in GaN-based field-effect transistors

We report results of the analytical and numerical investigation of self-heating effects in GaN-based high-power field-effect transistors. The problem of heat transfer in a transistor structure has been solved both analytically, using the method of images, and numerically. Two-dimensional electrothermal simulations of the GaN metal-semiconductor field-effect transistors on SiC and sapphire substrate have been performed in a framework of the drift-diffusion model. Using the physical-based simulations, we studied the dependence of the hot-spot temperature on the gate-to-gate pitch in the transistors with multiple gate fingers. Particular attention has been paid to comparison of self-heating effects in GaN transistors on SiC and sapphire substrates. The obtained results can be used for optimization of the thermal design of the GaN-based high-power field-effect transistors.