Unveiling Microstructural Damage for Leakage Current Degradation in SiC Schottky Diode after Heavy Ions Irradiation under 200 V

Single-event burnout and single-event leakage current (SELC) in SiC powerdevices induced by heavy ions severely limit their space application, and theunderlying mechanism is still unclear. One fundamental problem is lack ofhigh-resolution characterization of radiation damage in the irradiated SiCpower devices, which is a crucial indicator of the related mechanism. In thisletter, high-resolution transmission electron microscopy (TEM) was used tocharacterize the radiation damage in the 1437.6 MeV 181Ta-irradiated SiCjunction barrier Schottky diode under 200 V. The amorphous radiation damagewith about 52 nm in diameter and 121 nm in length at the Schottky metal(Ti)-semiconductor (SiC) interface was observed. More importantly, in thedamage site the atomic mixing of Ti, Si, and C was identified by electronenergy loss spectroscopy and high-angle annular dark-field scanning TEM. Itindicates that the melting of the Ti-SiC interface induced by localized Jouleheating is responsible for the amorphization and the formation of titaniumsilicide, titanium carbide, or ternary phases. These modifications at nanoscalein turn cause the localized degradation of the Schottky contact, resulting inthe permanent increase in leakage current. This experimental study providesvery valuable clues to thorough understanding of the SELC mechanism in SiCdiode.