GEANT4 analysis of energy deposition in CMOS photodiode under gamma-ray irradiation

CMOS image sensors (CIS) are more and more used in space applications. However, radiation induced dark-current noise degradation remains a dominant problem impacting the image quality. Especially, under total ionizing dose (TID) radiation, the energy deposited in the CMOS photodiodes generates numbers of defects which result in serious dark-current degradation. In order to estimate energy deposition under TID radiation, a method based on GEANT4 simulation is proposed in this paper, including the target-model founding, gamma-ray establishing, physical processes description, energy deposition calculation and data analysis. A detailed analysis is implemented to clarify the energy deposition in the different layers of the model.