Effects of 3-MeV Protons on 4H-SiC Bipolar Devices and Integrated OR-NOR Gates

Radiation effects of 3-MeV protons on 4H-SiC bipolar devices and integrated OR-NOR gates have been investigated. The chips were irradiated from a fluence of 1× 10⁸ cm^-2 until 1 × 10¹³ cm^-2. Up until a fluence of 1 × 10¹¹ cm^-2, both the bipolar devices and the logic gates were found to be stable, but for higher fluence, they begin to degrade as a function of irradiation fluence. Using TCAD simulations, degradation of the transistor current gain has been found to be more dominated by surface states than bulk defects generated by the proton irradiation. Simulations of logic circuits using SPICE show that the gain degradation is the key contribution to the unstable performance of the circuits from the fluence of 1 × 10¹² cm^-2 and above.