Investigation of Carrier Recombination in Si Heavily Irradiated by Neutrons

Variations of recombination lifetime, with fluence of the reactor neutrons from $10^{12}$ to $3×10^{16} n//cm^2$, in the magnetic field applied Czochralski grown Si samples are examined by the contactless transient techniques of the microwave probed photoconductivity and dynamic gratings. A nearly linear decrease in lifetime from few microseconds to about 200 ps within the examined range of neutron irradiation fluences was obtained. This dependence persists under relatively low (≤80°C) temperature heat treatments. Also, cross-sectional scans of lifetime depth-profiles were examined, which show rather high homogeneity of lifetime values within wafer thickness.