COMPARISON OF NEUTRON AND GAMMA-RAY DAMAGE IN n-TYPE SILICON

Fission‐spectrum neutron damage of n‐type, float‐zone silicon is compared with 60Co gamma‐ray damage. The damage was measured at 293°K by the degradation of the minority‐carrier lifetime. The room‐temperature damage coefficients, defined as K = (1/Φ) [(1/τai)−(1/τ0)], are 5.8×10−6 (neutrons/cm2)−1 sec−1 for neutron irradiation and 2.8×10−10 (photons/cm2)−1 sec−1 for gamma‐ray irradiation where τ0 and τai are the initial and after‐irradiation carrier lifetimes, and Φ is the integrated flux. The neutron damage coefficient is found to be independent of the irradiation temperature (76°–300°K) in contrast to a marked decrease with decreased irradiation temperature which has been observed in the gamma‐ray damage coefficient. Neutron damage recovery is observed over a broad temperature range from 60°–220°C, while gamma‐ray damage recovers sharply between 150° and 210°C. These results indicate that the energy transferred to the silicon recoils by the irradiating particle influences the number and kind of primary defects produced at 76°K and also affects defect reordering at higher temperatures.