Effects of SiO2 passivation on AlGaN/GaN HEMT by self-consistent electro-thermal-mechanical simulation

We have carried out systematic experiments based on degradation mechanisms of GaN high electron mobility transistors (HEMT). The electro-thermo-mechanical properties of AlGaN/GaN are simulated for reliability testing under different temperature and bias conditions. The effect of surface passivation on undoped AlGaN/GaN HEMT is investigated using SiO₂. This passivation layer can increase the electron density concentration. We have also performed the electro-thermal simulations to study the effect of passivation on selfheating, elastic energy and mechanical stress. Self heating phenomenon seems to be more uniform in case of passivated device. The SiO₂ passivation layer reduces the elastic energy to about 20% comparison with unpassivated device under the gate edge. The elastic energy near the gate edge is reduced which is the critical region for defect formation.