Analysis of ionizing radiation induced damage in charge coupled devices

Ionizing environment effects on CCD test devices are studied. Like MOS technology, CCD technology exhibits active and field oxide threshold voltage shift. Resulting from this shift, transfer efficiency degradation is observed on two phase CCD registers. On the other hand, 4 phase CCD registers working in specific conditions retain charge storage and transfer efficiency performances for a large total dose range. The dark current increase comes from peripheral insulation contribution. This degradation can result from a combination of mechanical stress induced by the bird´s beak and hole accumulation induced by the ionizing radiation in the peripheral insulator. These two effects contribute to increase the interface states density and, by field effect, to extend the area of the active interface states along the bird´s beak