Investigation of the current collapse behaviour in GaN power HEMTs with highly adjustable pulse and measurement concept

摘要

The dynamic RDSon or current collapse of Gallium Nitride (GaN) power HEMT devices was investigated under soft switching operation using a pulse test circuit, based on a half bridge configuration. The presented test and measurement setup allows device operation under adjustable high voltage and current with inexpensive measurement methods. A flexible adaption of the pulse pattern allows operation with and without biasing the device under test with high voltage before the pulse. Hence, the static and dynamic values of the RDSon can be determined in one single test setup under identical conditions and device configuration. Doing so, different stress conditions could be realized including variable drain-source blocking voltage VDS, off for adjustable stress time tstress and temperature.. The results show strong dependency of RDSon on the stress time and the drain-source voltage. Furthermore, indications of a strong influence of the trapping process on dynamic effects as well as an optimal operation for the devices at very low off-state stress times in application are observed.