In situ photodetection in strong radiation fields: Simultaneous irradiation of Si by photons and high-energy protons

Photoconductivity (PC) of crystalline Si induced by similar to 1 eV photon irradiation has been studied under simultaneous 17 MeV proton irradiation. The PC during simultaneous irradiation is suppressed to 20%-50% of the valu e without the proton irradiation. The PC-suppression rate depends on the ph oton energy, the proton flux, and the defect concentration. These dependenc es are explained with a saturated variation of conductivity increment Delta sigma during the proton irradiation. The saturation is mainly ascribed to bimolecular-type recombination of excess carriers under high-density excita tion. The understanding of the PC-suppression process contributes to the de velopment of photodetectors for use in strong radiation fields. Guidelines to limit the effect of the PC suppression are also discussed. (C) 2000 Amer ican Institute of Physics. [S0021-8979(00)01617-0].