Studies of deep levels in He+-irradiated silicon

Deep levels created in n-epitaxial silicon by alpha particle irradiation in the dose range from 10(9) to 10(13) particles/cm(2) have been investigated by the deep level transient spectroscopy technique and capacitance-voltage profiling. Under low fluence irradiation at least four main electron traps have been observed. With further increase in irradiation fluence, two new levels located at E-c - 0.56 eV and E-c - 0.64 eV appear on the high-temperature side of the DLTS signal. The slope change observed in the amplitude variations of the singly negative charge state of the divacancy versus the dose takes place when these two new levels appear. This suggests that both are multivacancy-related defects. After annealing at 350 degrees C for 15 min, all electron traps have disappeared. Moreover, no shallow levels are created during the annealing.