Failure Modes of 15-kV SiC SGTO Thyristors during Repetitive Extreme Pulsed Overcurrent Conditions

James A. Schrock, Emily A. Hirsch, Shelby Lacouture, Mitchell D. Kelley, Argenis V. Bilbao, William B. Ray, Stephen B. Bayne, Michael Giesselmann, Heather Obrien, Aderinto Ogunniyi

Research output: Contribution to journalArticlepeer-review

15 Scopus citations


SiC SGTO thyristors are an advanced solution for increasing the power density of medium voltage power electronics. However, for these devices to replace Si thyristor technology in industrial applications their characteristics and failure modes must be understood. This letter presents the failure modes of two 15-kV SiC SGTO thyristors during repetitive overcurrent conditions. The devices were evaluated with 2-kA (3.85 kA/cm2) square pulses of 100μs duration using a pulse forming network. Throughout testing, each devices' static characteristics were analyzed for signs of degradation; upon degradation, testing was ceased and the physical failure mode was determined through imaging with a scanning electron microscope (SEM) in conjunction with a focused ion beam. The electrical results demonstrate the failure modes of both SiC SGTO thyristors during pulsed overcurrents electrically manifested themselves as a conductive path through the gate-anode junction and an increased device on-state voltage. SEM imaging revealed one SiC thyristor formed an approximately 10μm wide cylindrical void, and the second SiC thyristor formed an approximately 200μm long crack. However, the experimental results demonstrate these 15-kV SiC SGTO thyristors' robust ability to repetitively switch at extreme high current density for tens of thousands of cycles.

Original languageEnglish
Article number7482767
Pages (from-to)8058-8062
Number of pages5
JournalIEEE Transactions on Power Electronics
Issue number12
StatePublished - Dec 2016


  • Failure modes
  • SiC
  • Thyristor
  • pulsed overcurrent
  • scanning electron microscope (SEM)


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