Trapping mechanism transition of γ-ray irradiation on p-GaN gate stack on gate applying voltage swing
Junyan Zhu, Jihong Ding, Keqing Ouyang, Xinbo Zou, Hong-Ping Ma, Liang Li, Debin Zhang, Jianjun Zhou, Yiwu Qiu, Xinjie Zhou, T. F. Wang, Wei Huang, David Wei Zhang
Abstract
The total ionizing dose effect of Mg-doped p-GaN gate stack have been investigated in this Letter on the whole gate voltage swing arranging from −1.3 to +1.5V. Additionally, two distinct kinds of mechanisms of trap effects have been extracted, which are response to in turns three phases of mechanism, voltage-controlled, coexist of voltage/current-controlled and current-controlled. It indicates that the fast traps are located at p-GaN/AlGaN interface (ET is about 0.295–0.333 eV), while the slow traps are located at AlGaN/GaN interface (ET is about 0.393–0.485 eV). They both have increasing trap density and broader range under γ-ray radiation. When the applied gate voltage rises to about 1 V, the effects of slow trap states are significantly weakened. However, the fast trap states barely change. Finally, the complete transition into current-controlled mode is observed at 1.5 V. What is more, p-GaN/AlGaN interface traps are further extracted near the gate turn-on voltage under γ-ray irradiation rather than the voltage-controlled mechanism of weak accumulation at the threshold voltage. Under the 600 krad γ-ray irradiation, the holes trap at p-GaN/AlGaN interface is identified with the trap activation energy ET at about 0.28–0.3 eV and trap density of about 4 × 1012 cm−2 eV−1. The increase in trap induces the reduction of gate current. In summary, this work can further our understanding of radiation tolerance and trapping effects of p-GaN gate high-electron mobility transistors for power switches, especially in regard to forward conduction status.