Investigation of carrier removal in electron irradiated silicon diodes

We present a detailed study of n++ silicon diodes irradiated with fluences of 1 MeV electrons high enough to cause device failure due to majority carrier removal. Capacitance–voltage (C–V) measurements were used to monitor the change in the carrier concentration of the base of the device as a function of radiation fluence. These were compared to the defect spectra in the same region obtained by deep level transient spectroscopy, and to the current–voltage characteristics of the device, both before and after annealing. We observed the expected deep levels with activation energies of 0.18 and 0.36 eV, but the C–V results imply that other trap levels must play a more important role in the carrier removal process.