Analysis of GaN power MOSFET exporsure to pulsed overcurrents

The advancement of wide bandgap semiconductor materials has led to the development of Gallium Nitride (GaN) power semiconductor devices, specifically GaN Power MOSFETs. GaN devices have improved characteristics in carrier mobility and on-state resistance compared to Silicon solid state switches. With the development of these new power semiconductor devices a need was established to understand the behavior of the devices switching performance under stress, with regards to situations in pulsing circuits. Through the examination of the switching characteristics of GaN devices, the results can be used for the improvement of advanced pulsing circuit design with GaN solid state switches. In this paper the authors develop a test bed to expose the GaN Power MOSFETs to single and repetitive pulsed overcurrents. The test bed was developed using a Pulse Ring Down board in a radially symmetric configuration to minimize the total equivalent inductance and resistance. The test bed switches the GaN MOSFET with low impedance between the DC bus and ground to induce the stress the MOSFET experiences during pulsed overcurrents. The DC characteristics were measured between switching sets to reveal characteristic signs of potential degradation and failure modes due to pulsed overcurrents. The single and repetitive pulse switching characteristics are captured, analyzed, and shown.