Cumulated dose long term effects in charge coupled devices

Abstract

Coupled Devices (CCD) has been experimentaly studied versus time and temperature. Early work shows that this current still increases after irradiation over thousands of hours at 300 K. Raising the temperature tends to increase or decrease the dark current, depending on postirradiation experimental conditions. The results can be interpreted, either considering the interface states density, or using the dependence of generation rate on surface potential. This paper shows that thermal activation in irradiation tests must be used only after a critical analysis of physical mechanisms and device structure.

Cobalt-60, proton and electron irradiation of a radiation-hardened active pixel sensor

“…Moreover, the time scale was likely too short to observe a significant effect (maximum 24 hours). Reverse annealing has been reported in the past on CCDs [14]. During annealing, competition between trapped charge recombination and interface state buildup will result in various possible evolutions of the dark current depending on time scale, applied bias and temperature.…”