Nuclear Technology / Volume 172 / Number 3 / December 2010 / Pages 295-301
Technical Paper / Materials for Nuclear Systems
Silicon carbide (SiC) is a promising semiconductor material for use in solid-state radiation detectors. SiC's wide bandgap makes it an appropriate semiconductor for high-temperature applications. Because of the annealing process that occurs at temperatures above 150°C for SiC, SiC semiconductors may function in a radiation environment for longer periods of time at elevated temperatures than at room temperature. Unlike thermal annealing effects that can act to improve the electrical characteristics of SiC, fast neutrons create displacement damage defects in SiC Schottky diodes through scattering and thus rapidly degrade the electrical properties of the SiC diodes.
We irradiated SiC Schottky diodes at the Ohio State University Research Reactor at room temperature with neutrons for displacement damage doses (Dd's) ranging from 7.6 × 1010 to 3.8 × 1011 MeV/g. After irradiation, we annealed the diodes, at either 175 or 300°C. We measured the SiC diodes' forward bias resistances at different steps of the experiments. To perform the experiments and study the results meaningfully, we performed a full factorial design of experiments with two factors: Dd and annealing temperature. The Dd factor had five levels of treatment, and the temperature had three levels of treatment. We did one-way and two-way analysis of variance to understand which factor is more dominant and whether or not the interaction effects are significant. It was determined that for Dd up to 2.3 × 1011 MeV/g the fractional damage recovery decreases with increasing Dd, but that Dd is not a significant factor affecting further changes in damage recovery for Dd's ranging from 2.3 × 1011 to 3.8 × 1011 MeV/g when the annealing temperature varies between 175 and 300°C. For high Dd (greater than 2.3 × 1011 MeV/g) neutron irradiations, the annealing temperature significantly affects the damage recovery.