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In this work, a new method for failure analysis of electronic components, high speed camera, is used to investigate burnout failure location of GaN HEMTs under RF overdrive stress. Based on the high speed camera system and the RF test system, we can filter out most of the burn flashes, and clearly locate the weak parts of devices. To further explain the burnout mechanism, a long-term (100 h) RF overdrive stress experiment was carried out and the significant degradation was observed. The drain-source current decreases and the threshold voltage drifts forward. These phenomena show that the degradation of RF overdrive stress is based on hot electron effect (HEE), which is related to the electric field. Besides, Electroluminescence (EL) tests are used and the non-uniform but strong luminescence characteristics of the gate were found, which indicates the strong electric field is the main cause of burnout. We also explore the correlation between burnout and ambient temperature. It was found that the influence of ambient temperature on the burnout was limited. At last, a TCAD simulation is carried out to confirm the temperature and electric field distribution in the device when burnout. It can be found that the electric field inside the device exceeded the breakdown electric field of GaN, which further proves that the burnout caused by RF overdrive is mainly due to electric field rather than temperature.

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