High energy electron radiation effect on Ni/4H-SiC SBD and Ohmic contact

The Ni/4H-SiC Schottky barrier diodes (SBDs) and transfer length method (TLM) test patterns of Ni/4H-SiC Ohmic contacts were fabricated, and irradiated with 1 MeV electrons up to a dose of 3.43×10¹⁴ e/cm^-2. After radiation, the forward currents of the SBDs at 2 V decreased by about 50%, and the reverse currents at -200 V increased by less than 30%. Schottky barrier height (\phi_\rm B) of the Ni/4H-SiC SBD increased from 1.20 eV to 1.21 eV under 0 V irradiation bias, and decreased from 1.25 eV to 1.19 eV under -30 V irradiation bias. The degradation of \phi_\rm B could be explained by the variation of interface states of Schottky contacts. The on-state resistance (R_s) and the reverse current increased with the dose, which can be ascribed to the radiation defects in bulk material. The specific contact resistance (\rho_\rm c) of the Ni/SiC Ohmic contact increased from 5.11× 10⁵ \Omega\cdotcm² to 2.97×10^-4 \Omega\cdotcm².