Power cycling reliability results of GaN HEMT devices

The GaN HEMT is a novel wide bandgap device which could improve the overall efficiency and at the same time shrink the system size. In order to verify the reliability of this promising semiconductor device, new measurement and testing methods have to be developed. In this work, as a general basis for performing reliability tests junction temperature measurement methods for GaN HEMT were investigated. By using suitable temperature measurement method, several power cycling tests were performed on GaN HEMT from three different manufacturers. The main failure mechanism of the GaN HEMT from two manufacturers under power cycling tests is the degradation of solder layer between device and printed circuit board. The main failure mechanism of the devices from the third manufacturer is bond wire lift-off. In GaN the piezoelectric effect is involved in the formation of the 2DEG, and electrical characteristics are sensitive to compressive and tensile stress. The question is whether repetitive deformation leads to new failure mechanisms compared to Si devices.