Anokhin I. Effect of neutron and ionizing irradiation on physical properties of silicon structures.

Behavior of the Fermi level and concentration of free carriers in high-resistivity silicon under the fast neutron irradiation and the effect of nonuniform distribution of an electric field on processes of the charge collection in silicon strip-detectors under short-range particles irradiation have been studied theoretically. Effect of the Fermi level stabilization under neutron irradiation of the high-purity silicon may be explained by formation the stable multi-charged amphoteric center (divacancy), which becomes dominating at high doses. It has been shown that changes of equilibrium resistivity of silicon under irradiation at doses more than 2-3 kRad gives a main contribution into shift I-V characteristics of p-i-n diodes. Distribution of electric field in position-sensitive silicon strip-detectors has been calculated. It has shown, that accuracy of coordinates determination for particles incident between strips essentially depends on detector geometry and electric field distribution. The obtained re sults were used for development of a new class of emergency neutron dosimeters, which were used in INR NASU and Chernobyl power plant, and for measurement of radiation fields at CERN accelerator.