Identification of Pre-Catastrophic Failure Mechanisms in High Power GaN HEMT

Abstract. The research describes an investigation into an observed phenomenon believed to be correlated with catastrophic device failure cause by the breakdown in the gate structure in high power, high frequency GaN HEMTs. Several devices that were stressed on an elevated temperature extended reliability test station showed significant changes in gate current prior to catastrophic failure. In an effort to electrically examine the devices during the breakdown process, similar devices were stressed on wafer. Detailed measurements were performed on the devices at regular intervals. On several devices, the behavior of interest was reproduced. Of the periodic measurements performed, a gate current sweep provided the greatest insight into device operation. Explanations for the observed phenomena are discussed.