Abstract :
The damage coefficient at 298°K of copper-contaminated N+P diodes is smaller than that of non-contaminated ones. In these copper-contaminated samples,the higher the bulk resistivity is,the smaller is the damage coefficient. For non-contaminated diodes, the damage coefficient of samples of pulled bulk crystals is smaller than that of floating zone crystals, and the higher bulk resistivity diodes have smaller damage coefficient. At 217°K measurement,the effect of copper-contamination on the damage coefficient could not be observed. The energy levels of defects introduced by gamma ray irradiation are ~0.30eV, and ~0.28eV with non-contaminated FZ 135 ohm-cm and CZ 10 ohm-cm bulk samples, respectively. In copper-contaminated samples,~0.60eV and ~0.45eV are obtained as the defect energy levels for FZ 135 ohm-cm and CZ 10 ohm-cm bulk samples.
