Access Region Stack Engineering for Mitigation of Degradation in AlGaN/GaN HEMTs With Field Plate

Electric field in a device varies as it switches between ON and OFF states. These states have different intensities of electric field and carrier density. The regions having high electric field affects reliability of a GaN-HEMT. In a AlGaN/GaN HEMT, degradation primarily initiates as a result of electric field crowding near its edges. The present work aims at suppressing high electric field in the SEMI-ON state at the field plate edge by incorporating a SiO2pocket at its edge. Numerical analysis is performed using a calibrated setup to investigate viability and performance of the proposed device. It is found that the electric field and electron temperature in the SEMI-ON state reduce significantly by incorporating a SiO2pocket around the field plate edge in the drain access region. For the device having SiO2pocket with diamond and passivation layer thickness kept at 30 nm each, the electric field, carrier temperature, and self heating reduces by 43%, 20%, and 13%, respectively at the field plate edge along with 47% reduction in the thermal resistance.