Gate Failure Behavior and Mechanism of AlGaN/GaN HEMTs under Transmission Line Pulsed Stress

Abstract

The failure behavior and the corresponding physical mechanism of the AlGaN/GaN high electron mobility transistors (HEMTs) under transmission line pulse (TLP) stress were investigated in this paper. The result shows that the output and transfer characteristics of the AlGaN/GaN HEMTs after 90 cycles begin to degrade by comparing with the fresh ones under 40 V TLP voltage, and the gate leakage current of the devices slightly increases. When the TLP voltage of 52 V was applied, a catastrophic failure occurs for the AlGaN/GaN HEMTs. Furthermore, the failure of the AlGaN/GaN HEMTs was located, and the micro-morphology of the abnormal spot was observed. The result shows that the gate metal was damaged due to the large TLP stress. The failure mechanism may be mainly attributed to the Joule heat that causes the high lattice temperature of 1160 K as well as the electric field, and it is higher than the melting point of Au (1064 K) in the gate metal (Au/Ti/Mo). The results may be useful in the design and application of electrostatic discharge (ESD) for AlGaN/GaN HEMTs.