Step-graded AlGaN vs superlattice: Role of strain relief layer in dynamic on-resistance degradation

In this work, we study the impacts of different types of strain relief layer (SRL) on dynamic on-resistance (Ron) degradation of GaN power devices on Si by back-gate ramping and vertical leakage measurement. Our study reveals that the SRL has important effects on the dynamic Ron. Compared with step-graded AlGaN SRL, the superlattice SRL possesses much more energy barriers, which can more effectively block the leakage of holes from GaN buffer and the injection of electrons from Si substrate. Enhancing the carrier blocking ability of SRL could contribute to the suppression of dynamic Ron degradation.