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$\times 10^{14}$~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 ($R_{\rm s}$) 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$\times 10^{ - 5}~{\Omega}\cdot$\,cm$^{2}$ to 2.97$\times $10$^{ - 4}~{\Omega}\cdot$\,cm$^{2}$.