Analysis of the degradation of AlGaN/GaN HEMTs by high-temperature operation tests

In this paper, we study the degradation phenomenon and its effect on the lifetime of AlGaN/GaN HEMTs by means of high-temperature operation tests. To estimate the self-heating effect, we performed electrical measurements at several temperatures. Packaged devices were tested at various bias levels and a plate temperature of 150 °C. The lifetime of devices strongly depended on the junction temperature. By means of electrical characterization, the device degradation was demonstrated and evaluated. After the operation test, the drain current and the transconductance were found to be decreased and the threshold voltage was shifted in a positive direction. The leakage current was remarkably decreased. On the basis of the experimental results, the degradation is ascribed to the hot electron effect and to Schottky contact degradation.