Effect of Threshold Voltage Hysteresis on Switching Characteristics of Silicon Carbide MOSFETs

• Published in: IEEE transactions on electron devices Vol. 68; no. 10; pp. 5014 - 5021
• Main Authors: Cai, Yumeng, Xu, Hao, Sun, Peng, Ke, Junji, Deng, Erping, Zhao, Zhibin, Li, Xuebao, Chen, Zhong
• Format: Journal Article
• Language: English
• Published: New York IEEE 01-10-2021; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Delays; Dynamic characteristics; Gate structure; Hysteresis; interface state density; Interface states; Logic gates; MOSFETs; OFF-state starting voltages; Reliability analysis; Silicon carbide; silicon carbide (SiC) MOSFETs; Static characteristics; Switches; Switching; switching characteristics; Threshold voltage; threshold voltage (<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) hysteresis
• ISSN: 0018-9383; 1557-9646
• DOI: 10.1109/TED.2021.3101459

Threshold voltage (<inline-formula> <tex-math notation="LaTeX">{V}_{\text {TH}} </tex-math></inline-formula>) hysteresis affects the reliability of silicon carbide (SiC) MOSFETs. To evaluate the <inline-formula> <tex-math notation="LaTeX">{V}_{\text {TH}} </tex-math></inline-formula> hysteresis effect on switching characteristics, this article first investigates the <inline-formula> <tex-math notation="LaTeX">{V}_{\text {TH}} </tex-math></inline-formula> hysteresis in the static characteristics of three SiC MOSFETs with different gate structures. The results illustrate the density of the interface states in different gate structures. Then, the effect of <inline-formula> <tex-math notation="LaTeX">{V}_{\text {TH}} </tex-math></inline-formula> hysteresis on dynamic characteristics under varying OFF-state starting voltages (<inline-formula> <tex-math notation="LaTeX">{V}_{\text {G}}^{ \mathrm{\scriptscriptstyle OFF}} </tex-math></inline-formula>) is evaluated by experiment. Furthermore, the effect mechanism of <inline-formula> <tex-math notation="LaTeX">{V}_{\text {TH}} </tex-math></inline-formula> hysteresis and <inline-formula> <tex-math notation="LaTeX">{V}_{\text {G}}^{ \mathrm{\scriptscriptstyle OFF}} </tex-math></inline-formula> on switching characteristics is analyzed. Under the effect of the <inline-formula> <tex-math notation="LaTeX">{V}_{\text {TH}} </tex-math></inline-formula> hysteresis, a smaller <inline-formula> <tex-math notation="LaTeX">{V}_{\text {G}}^{ \mathrm{\scriptscriptstyle OFF}} </tex-math></inline-formula> reduces <inline-formula> <tex-math notation="LaTeX">{V}_{\text {TH}} </tex-math></inline-formula> when the device turns on. This phenomenon leads to a reduction in the turn-on delay and consequently lowers the turn-on loss. Therefore, the <inline-formula> <tex-math notation="LaTeX">{V}_{\text {TH}} </tex-math></inline-formula> hysteresis is a significant factor for gate driver design of SiC MOSFETs.