New electrically active centers with negative U are revealed in oxygen
-rich Si crystals saturated with hydrogen and irradiated by fast elect
rons, These centers have been observed after heat treatment of the irr
adiated crystals at temperatures ranging from 275 to 350-degrees-C. Oc
cypancy level of given defects (E(-/+) congruent-to E(c)-0.075 eV) and
their composition have been determined.