ANALYSIS OF NEUTRON DAMAGE IN HIGH-TEMPERATURE SILICON-CARBIDE JFETS

Neutron-induced displacement damage effects in n-channel, depletion-mode junction-field-effect transistors (JFETs) fabricated on 6H-silicon carbide are reported as a function of temperature from room temperature (RT) to 300 degrees C. The data are analyzed in terms of a refined model that folds in recently reported information on the two-level ionization energy structure of the nitrogen donors. A value of 5 +/- 1 cm(-3) per n/cm(2) is obtained for the deep-level defect introduction rate induced by the neutron irradiation. Due to partial ionization of the donor atoms at RT, the carrier removal rate is a function of temperature, varying from 3.5 cm(-1) at RT to 4.75 cm(-1) at 300 degrees C. The relative neutron effect on carrier mobility varies with temperature approximately as T--7/2, dropping by an order of magnitude at 300 degrees C compared with the RT effect. The results offer further support for the use of SIC devices in applications which combine high-temperature and severe radiation environments, where the use of Si and GaAs technologies is limited.