Bias dependence and bistability of radiation defects in silicon

Influence of bias on effective dopant concentration in neutron and pion irradiated p+ - n - n+ diodes has been measured. Detailed studies of annealing of the bias-induced damage have revealed three components, with introduction rates from 0.005 to 0.008 cm−1 and annealing time constants ranging from 5 to 1000 h at 20°C. Variation of annealing temperatures yielded activation energies around 1 eV for all the three components. Bistable behavior of radiation damage under bias has been observed and its activation and annealing studied. The bistable damage was associated to the fastest annealing component of bias-induced damage. Using the parameterization obtained, a prediction for ATLAS SCT operation was made. Bias-induced damage is shown to require an additional 80 V to fully deplete detectors at the end of LHC operation.