First Characterization of Si IGBT, SiC MOSFET, and GaN HEMT at Deep Cryogenic Temperatures Down to 10 Millikelvins

Electrical energy conversion at deep cryogenic temperatures (TON) test. At TONdecreasing by 4 times compared to room temperature. This can be explained by the trap freeze-out and increased channel mobility. Differently, SiC MOSFET becomes non-Ohmic below ∼60 K. The knee voltages (VK) of SiC MOSFET and Si IGBT both increase at lower temperatures, leading to elevated conduction loss. The sustained current conduction and high VKin lowly-doped SiC and Si drift layers, despite carrier freeze-out, can be explained by the shallowlevel impact ionization with donor states. These findings lay the foundation for developing deep cryogenic power electronics at temperatures below the current operational boundaries.