Observation of Dynamic VTH of p-GaN Gate HEMTs by Fast Sweeping Characterization

• Published in: IEEE electron device letters Vol. 41; no. 4; pp. 577 - 580
• Main Authors: Li, Xiangdong, Bakeroot, Benoit, Wu, Zhicheng, Amirifar, Nooshin, You, Shuzhen, Posthuma, Niels, Zhao, Ming, Liang, Hu, Groeseneken, Guido, Decoutere, Stefaan
• Format: Journal Article
• Language: English
• Published: IEEE 01.04.2020
• Subjects: <italic xmlns:ali="http://www.niso.org/schemas/ali/1.0/" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">V TH shift; fast sweeping; Gallium nitride; HEMTs; Integrated circuits; Logic gates; MODFETs; p-GaN gate HEMT; PBTI; Stress; Switches
• ISSN: 0741-3106
• DOI: 10.1109/LED.2020.2972971

In this work, fast sweeping characterization with an extremely short relaxation time was used to probe the <inline-formula> <tex-math notation="LaTeX">{V}_{\text {TH}} </tex-math></inline-formula> instability of p-GaN gate HEMTs. As the <inline-formula> <tex-math notation="LaTeX">{I}_{\text {D}} </tex-math></inline-formula>-<inline-formula> <tex-math notation="LaTeX">{V}_{\text {G}} </tex-math></inline-formula> sweeping time deceases from 5 ms to <inline-formula> <tex-math notation="LaTeX">5~\mu \text{s} </tex-math></inline-formula>, the <inline-formula> <tex-math notation="LaTeX">{V}_{\text {TH}} </tex-math></inline-formula> 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 <inline-formula> <tex-math notation="LaTeX">{V}_{\text {TH}} </tex-math></inline-formula> features a very fast shifting process but a slower recovering process. D-mode HEMTs counterpart without Mg contamination demonstrates a negligible <inline-formula> <tex-math notation="LaTeX">{V}_{\text {TH}} </tex-math></inline-formula> shift and hysteresis, proving the <inline-formula> <tex-math notation="LaTeX">{V}_{\text {TH}} </tex-math></inline-formula> instability is probably due to the ionization of acceptor-like traps in the p-GaN depletion region. Finally, the <inline-formula> <tex-math notation="LaTeX">{V}_{\text {TH}} </tex-math></inline-formula> instability is verified by a GaN circuit under switching stress. The <inline-formula> <tex-math notation="LaTeX">{V}_{\text {TH}} </tex-math></inline-formula> instability under different sweeping speed uncovers the fact that the high <inline-formula> <tex-math notation="LaTeX">{V}_{\text {TH}} </tex-math></inline-formula> by conventionally slow DC measurements is probably artificial. The DC <inline-formula> <tex-math notation="LaTeX">{V}_{\text {TH}} </tex-math></inline-formula> should be high enough to avoid HEMT faulty turn-on.