Observation of Dynamic <i>V</i> <sub>TH</sub> of p-GaN Gate HEMTs by Fast Sweeping Characterization
Xiangdong Li, Benoit Bakeroot, Zhicheng Wu, Nooshin Amirifar, Shuzhen You, Niels Posthuma, Ming Zhao, Hu Liang, G. Groeseneken, Stefaan Decoutere
Abstract
In this work, fast sweeping characterization with an extremely short relaxation time was used to probe the V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TH</sub> instability of p-GaN gate HEMTs. As the ID-VG sweeping time deceases from 5 ms to 5 μs, the V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TH</sub> dramatically degenerates from 3.13 V to 1.76 V, meanwhile the hysteresis deteriorates from 22.6 mV to 1.37 V. Positive bias temperature instability (PBTI) measurement by fast sweeping shows the V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TH</sub> features a very fast shifting process but a slower recovering process. D-mode HEMTs counterpart without Mg contamination demonstrates a negligible V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TH</sub> shift and hysteresis, proving the V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TH</sub> instability is probably due to the ionization of acceptor-like traps in the p-GaN depletion region. Finally, the V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TH</sub> instability is verified by a GaN circuit under switching stress. The V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TH</sub> instability under different sweeping speed uncovers the fact that the high V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TH</sub> by conventionally slow DC measurements is probably artificial. The DC V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TH</sub> should be high enough to avoid HEMT faulty turn-on.