Enhanced dark current generation in proton-irradiated CMOS active pixel sensors

The dark current increase due to proton-induced displacement damage is studied in a standard and a radiation-hardened CMOS active pixel sensor (APS). Several devices have been irradiated with protons of different energies and fluences. The influence of the proton energy and fluence on the mean dark current increase and the dark current nonuniformity is investigated. Dark current density histograms are obtained by the theory based on collision kinematics. They are determined by the number of elastic and inelastic collisions and the damage these interactions create in the pixel sensitive volume. It is shown that field enhanced emission has to be taken into account to predict accurately the distribution of the dark current density increase. We also compare the results with data found in literature for charge coupled devices (CCD) and charge injection devices (CID).