Radiation damage in scientific charge-coupled devices

Two important classes of radiation damage to the scientific CCD are discussed, namely bulk and ionization effects. Bulk damage or displacement damage is a process in which silicon atoms are displaced from their normal lattice positions by high energy photons or particles. Single atomic displacements or cluster defect damage in silicon is produced depending on the energy and type of radiation experienced by the detector. Bulk damage creates trapping sites within the CCD´s signal channel which in turn degrades CTE performance. Ionization-induced damage induces a buildup of charge in the CCD´s gate insulator causing the sensor´s drive operating windows to shift (i.e. flat-band shift). In addition, ionization damage creates unwanted electronic sites at the gate´s interface causing the CCD´s dark current to increase