MODELING AND SIMULATION OF CHARGE COLLECTION PROPERTIES FOR NEUTRON-IRRADIATED SILICON DETECTORS

Charge collection deficiencies for neutron irradiated silicon p+/n/n+ junction detectors are calculated from the interaction between the free carriers generated by particles to be detected and traps created by neutron radiation. The current induced on collection electrode as a function of time by free carriers moving in the detector electrical field is presented. Alpha (alpha) particle and minimum ionization particle (MIP) induced current shapes were simulated in various electrical field conditions including the reversal of the field in the case of ''type inversion''. The simulation based on alpha-particle data predicts that the charge collection deficiency of MIP for neutron damaged detector with the thickness of 350 mum after 1 x 10(14)n/cm2 would be less than 20 % when operated at a bias of 260 volts.