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.