Effects of radiation on buried-channel CCDs with doped polysilicon gates and undoped polysilicon interelectrode isolation

Abstract

The effects of gamma radiation on the operation of a buried-channel charge-coupled device having doped polysilicon electrodes and undoped polysilicon interelectrode isolation were studied. Doses up to 1×104 rad caused no increase in the transfer inefficiency. At a dose of 3×104 rad, the flat-band voltage shift was sufficient to drive the buried channel out of depletion and to cause field-induced channeling in the undoped polysilicon isolation regions. Increasing the channel bias returned the channel to depletion. However, channeling of the isolation regions could not be eliminated by changing the clock and bias voltages.