Special Degradation Effects of ⁶⁰Co <i>γ</i>-Rays Irradiation on Electrical Parameters of SiC MOSFETs

Abstract

The static and dynamic characteristics of silicon carbide (SiC) metal–oxide–semiconductor field-effect transistors (MOSFETs) under gate and drain biases exhibit differential degradation after irradiation. Total ionizing dose (TID) irradiation caused threshold voltage shift and switch response degradation, and the degradation trends of these two parameters were not the same dependence on the bias. The threshold voltage of devices under test (DUT) shifted toward negative due to the radiation-induced positive oxide trapped charges. Turn-off time ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${t} _{\text {off}}$ </tex-math></inline-formula> ) was more sensitive to TID irradiation compared to turn-on time ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${t} _{\text {on}}$ </tex-math></inline-formula> ). The switch response changed after irradiation due to parasitic capacitance gate-to-drain capacitance (CGD) and threshold voltage degradation. It has been verified by Sentaurus TCAD 2-D simulations that the high-speed accumulation of gate oxide traps in the localized region of the trench gate MOS [U-shaped trench-gate metal–oxide–semiconductors (UMOS)] due to the nonuniform distribution of the electric field is the main reason for the special degradation of electrical parameters under drain bias. For TID radiation damage evaluation and radiation hardening of SiC MOSFETs under different biases, both static and dynamic performances should be considered. The experimental results provide valuable insights into the behavior of SiC MOSFETs under radiation and are crucial for designing reliable electronic systems for space and nuclear applications.

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