Influence of Transport Mechanism and Defect Behavior on Leakage Current in 4H-SiC JBS Diodes After Neutron Irradiation

The degradation mechanism of leakage current in 4H-silicon carbide (SiC) junction barrier Schottky (JBS) diode after neutron irradiation is studied in this work. The experiment result shows that the forward current of diode was decreased after equivalent 1-MeV neutron irradiation at a fluence of 1× 10¹⁴ n/cm². Interestingly, the reverse leakage current was decreased when the reverse voltage is 0-406 V and increased when the reverse voltage is greater than 406 V. By analyzing the forward current with the thermionic emission (TE) model and the C-V characterization, neutron irradiation increases the height of Schottky barrier, which reduces the carrier concentration. The reverse leakage current is closely related to the electric field. When the electric field is sufficiently large, the reverse leakage current is dominated by the thermal field emission (TFE) model. The measurements using deep-level transient spectroscopy (DLTS) show that neutron irradiation introduces deeper energy levels and higher concentrations of receptor defects. These defects led to an increase in the tunneling electric field and produced carrier removal effects. Notably, the defects dominate the degradation of leakage current after neutron irradiation.