R. Kupper

The impact of proton energy on total ionizing dose and displacement damage effects has been investigated in commercial 4H-SiC vertical power MOSFETs at ultra-high doses. Devices were irradiated with 1 MeV and 3 MeV protons, which resulted in different penetration ranges of the primary particles. The corresponding peak in non-ionizing energy loss is located in the epitaxial region for 1-MeV protons and in the substrate of the device for 3-MeV protons. In parallel, deep-level transient spectroscopy was performed on irradiated 4H-SiC wafers to analyze the formation of electrically active defects produced by protons of the same energies. A correlation between electron trap concentration and effective doping reduction was observed, confirming the role of these defects in carrier compensation and their direct impact on the electrical degradation observed in the commercial SiC power MOSFETs.

This study explores the total ionizing dose (TID) and displacement damage (DD) effects in trench silicon carbide (SiC) power MOSFETs. The effects of X-ray irradiation reveal significant negative shifts in the threshold voltage, particularly evident in devices biased with positive gate bias. The TID effects in those devices are visible at doses as low as 10 krad(SiO ₂ ), indicating the higher TID sensitivity of trench devices compared to some planar counterparts. Exposure to 3-MeV protons leads to substantial reductions in drain current induced by a fall in the transconductance, while no damage to the gate oxide is observed up to doses of 50 Mrad(SiO ₂ ). The substantial degradation of transconductance indicates DD, which become prominent at doses exceeding 10 Mrad(SiO ₂ ). Both trench and planar devices exhibit similar DD-induced effects, suggesting a common underlying mechanism linked to defects within the epitaxial SiC layer.