The investigation of AlGaN/GaN HEMT failure mechanisms under different temperature conditions

To explore degradation law and failure mechanisms of AlGaN/GaN HEMT under different temperature conditions, the step-temperature stress experiments are carried out. The results show that the drain-source current decreases with the aging time when the junction temperature range from 139 degrees to 200 degrees; while the drain-source current increases with the aging time when the junction temperature range from 200 degrees to 352 degrees. When the junction temperature is less than 200 degrees, the AlGaN ionized donor atoms cause the Schottky barrier height of the AlGaN/GaN HEMT device to rise; and when the junction temperature is higher than 200 degrees, the diffusion of impurities oxygen in surface causes the Schottky barrier height of the AlGaN/GaN HEMT device to fall. The barrier height can affect the threshold voltage which leads to the change of drain-source current. Therefore, the degradation of the drain-source current is caused by the change of the Schottky barrier height.