No abstract

In this study, the current-transient method has been conducted to investigate the trap states in p-GaN gate high-electron-mobility transistors (HEMTs) under reverse gate stress. An irregular threshold voltage shift under reverse gate bias has been observed through the pulsed transfer measurements with different delay times. It suggests that both the hole insufficiency and hole trapping are generated during the reverse gate pulse bias. With proper selection of the delay time based on the pulsed characterizations, the hole detrapping can be effectively evaluated after the hole recovery is completed. In addition, by subtracting the trapping behavior caused by the measurement condition, the actual detrapping transient under reverse gate filling voltages can be obtained with the current-transient method. Three traps have been observed with the energy levels of 0.484, 0.390, and 0.235 eV. The identification of hole traps may provide a basis on the understanding of threshold voltage instability and further improvement of the reliability of p-GaN gate HEMTs.

The effects of gamma irradiation on the electrical and trapping properties of AlGaN/GaN high-electron-mobility transistors (HEMTs) are investigated in detail. During the irradiation, the gate-source leakage current of the HEMT is monitored online when applying a reverse gate voltage. The variations of electrical properties of the device, including an increase in drain-source current, the negative threshold voltage shift, and a decrease of leakage current, are observed. In particular, three traps in the device are identified using the voltage-transient method and the variations of these traps after irradiation are also investigated. The results show that the absolute amplitudes of the three traps in the device decrease after irradiation, which indicates a reduction in the density of the traps. Furthermore, it is proposed that the time constants and energy levels of the three traps decrease after irradiation. The observed changes in the trapping behaviors are ascribed to the structural ordering of the defects, which is consistent with the improvement in the electrical characteristics of the device.

No abstract

No abstract