Characterization and Failure Mechanism Study of Ohmic Gate GaN HEMT under Overcurrent Stress

This paper investigates ohmic gate P-GaN HEMTs’ overcurrent capabilities and the associated failure mechanisms through single pulse overcurrent conduction stress experiments. A series of tests were performed on the devices under varying overcurrent stress conditions, including different pulse widths and gate injection current. Based on the experimental results and TCAD simulation, the degradation mechanisms and failure modes of the overcurrent capability are thoroughly analyzed and studied. It is revealed that the main reason for the two failure modes is the accumulation of thermal stresses in the access region due to the progressive increase of electric field under overcurrent stress condition.