  Single-event burnout and single-event leakage current (SELC) in SiC power
devices induced by heavy ions severely limit their space application, and the
underlying mechanism is still unclear. One fundamental problem is lack of
high-resolution characterization of radiation damage in the irradiated SiC
power devices, which is a crucial indicator of the related mechanism. In this
letter, high-resolution transmission electron microscopy (TEM) was used to
characterize the radiation damage in the 1437.6 MeV 181Ta-irradiated SiC
junction barrier Schottky diode under 200 V. The amorphous radiation damage
with about 52 nm in diameter and 121 nm in length at the Schottky metal
(Ti)-semiconductor (SiC) interface was observed. More importantly, in the
damage site the atomic mixing of Ti, Si, and C was identified by electron
energy loss spectroscopy and high-angle annular dark-field scanning TEM. It
indicates that the melting of the Ti-SiC interface induced by localized Joule
heating is responsible for the amorphization and the formation of titanium
silicide, titanium carbide, or ternary phases. These modifications at nanoscale
in turn cause the localized degradation of the Schottky contact, resulting in
the permanent increase in leakage current. This experimental study provides
very valuable clues to thorough understanding of the SELC mechanism in SiC
diode.
