RADIATION-DAMAGE BY NEUTRONS AND PHOTONS TO SILICON DETECTORS

Observations have been made of the behaviour of silicon diodes and microstrip detectors after exposures of up to 2 X 10(14) neutrons cm-2 and 4 Mrad Co-60 photons. Results are presented on leakage currents and doping concentration of the substrate material of neutron damaged devices. Important changes in the effective doping of the substrate have been observed to take place during the room temperature annealing of the material, particularly after high neutron fluences. Over times of more than one year further doping changes occur which increase the depletion voltage of type inverted material and may set an ultimate lifetime limit for silicon detectors in future hadron colliders. Measurements have been made of the performance of double sided microstrip detectors constructed using a field plate isolation technique on the n-type surface. After high doses of both neutrons and photons good interstrip isolation is maintained, demonstrating one potential technique for radiation tolerant microstrip fabrication.